GROWING NAMED BEGONIAS FOR CUT BLOOM EXHIBITION
By Robert Bryce
Begonia plants grow best and thrive in a covered, well ventilated and shaded environment with a constant growing temperature of 65 degrees. As we all know this is impossible to achieve throughout the whole growing season, especially in the UK.
My set up is a compromise situation; I grow my begonias in two aluminium Elite type greenhouses a 20ft x 10 ft and a 16 ft x 8 ft. The height of the greenhouses is standard but I would like it to be higher as this would reduce the excessively high temperatures experienced each summer (heat edges the begonia blooms). Around one quarter of the glass in each greenhouse provides top vents, louvre vents and doors allowing ventilation at the appropriate times during the growing season to reduce the temperature. My staging is provided by wooden slats and set at a height approximately 18 inches from the floor. Slatted staging allows a free flow of air around the plants keeping the plants healthy and reducing the chances of disease. The floors in my greenhouse comprise a path 24 inches wide with the remainder being earth covered by 4 inches of pebbles. This allows a moist, cool atmosphere to be created if water is hosed on the floor. My shading as required throughout the season is provided by Coolglass a proprietary shade solution available at all garden centres and a white fleece fabric bought from LBS Polythene, Colne, England. I grow in both clay and plastic pots. The only difference is weight and clay pots need watering more often. In order to start tubers early and provide an environment for the successful rooting of cuttings I have a number of home made propagators constructed using wooden planks, heating cables, a thermostat and horticultural sand. The cables should be spaced so that the propagator can provide a temperature of 70 degrees F even at the coldest time of the year.
My growing season and methods are discussed in the diary below.
After competing the harvest of all my tubers I remove any growing plants or tubers of any description from the area, I open the vents and doors and allow frost to kill all the over wintering insects. After there has been several days of frost I commence on my cleaning program.
I clean the pots, trays, propagators, greenhouse, canes, ties and the floor by washing down with a disinfectant (usually Jeyes Fluid). If there are algae present on the glass I use a pressure washer to remove it. After cleaning I close all the ventilators and doors and finally fumigate, using a sulphur candle, this provides a good clean start for the new season ahead.
I check over all and electrical equipment in the greenhouse i.e. propagators, fans and lights. Remember, it is better to be alive than dead!
I order and attain all compost and fertilisers that I will require in the new season. I order my compost from Singletons in Cumbria and my fertilisers from Chempak.
Some days I contemplate the previous season and make notes of how I can improve.
If you are going to make your own composts you should start to collect all the ingredients of your compost, ie sand, peat, leaf mould, manure, loam and fertilisers.
When purchasing compost or fertiliser ensure you buy it from a reputable source. Compost stored for long periods outside in the open is a liability (rooting will be affected and tuber losses will result), always check the manufactured date shown on the sack, last year is no good. If in doubt do not buy as trouble will surely result!
This is the month when the adult tubers (cutting tubers are too small) are given the hot water treatment prior to starting. I recommend this as a precaution and treatment of Leaf Eelworm an additional benefit is that it helps generate more shoots from the tuber resulting in additional basal cuttings. The treatment is as follows:-
Immerse the dormant tubers in hot water at a temperature of 115°F for 15 minutes (this temperature must be constant for the full 15 minutes if you have seen leaf eelworm in the previous growing season) remove the tuber, and immerse in a solution of fungicide (Benlate) in cold water for a further 5 minutes. Remove, dry off in a cool room on newspaper and place in warm starting compost.
I start my adult tubers for exhibition at Birmingham on the 4th Saturday of the month. This fits in with the temperature that my propagators can generate at this time of year. I fill cat litter trays (with drainage holes) with my starting compost, water them and place them on the sand bed for a week before burying my tubers in the compost. The temperature in the propagator is kept as near to 65°F as possible. After the tubers are buried the propagators are covered with a single layer of fleece spaced 2 inches above the compost to help retain heat whilst allowing the compost to breathe. Tubers are covered by approximately ¼ inch of compost.
My starting compost is as follows:
Singletons soiless seed compost. I use this for starting because the added fertiliser is light and I believe excess fertiliser around tubers can cause rot at this early stage of the year. An added benefit is that end of the season the harvested tubers appear plumper when surrounded by soiless compost at starting (retention of moisture?).
If you are mixing your own starting compost use:
1 part sedge peat (good quality only), 1 part sharp 1/8” grit or Perlite to each bushel (8 gallons). Add Chempak seed fertiliser as to manufacturer’s instructions.
Whichever compost you use add a protection against vine weevil which is now rife throughout the country. These are changing all the time but Aldrin the best one is now banned under the Montreal Protocol. Suscon Green and Provado are alternatives. If Provado is used it should be watered in every 3 months to remain active.
Note: If a number of varieties are grown, it is advisable to keep each variety to its own starting tray due to the time it takes different varieties to start, however starting is always erratic.
During the starting period I keep the sand in the propagator moist as this helps to conduct the heat into the starting trays. I remove the trays about once a week to apply a quantity of lukewarm water to the sand. It is essential to keep the newly forming roots moist – but only just moist – over watering can be disastrous at this or any other time during the growing season. Learning the correct way to water is the hardest horticultural skill to attain. Under watering causes the formed roots to burn, over watering drowns the roots. Both result in tuber losses if not quickly corrected. Use your fingers to check if the compost is moist from top to bottom, that’s what God gave them you for to feel!.
Throughout March, I check through the tubers in the propagators to see if they have started. I do this by carefully scraping away the top ¼ inch of compost and check for those beautiful pink growing eyes and white roots, the first signs of life. If any do not show signs of starting (either pink eyes or root formation) I lift them to check their condition. If they are soft when gently squeezed, I discard otherwise I cover them again with compost and check again a few days later. This is an exciting time of year for me but prepare for some tuber losses, this always happens and can be very disappointing if it is the only one of a variety.
When the tubers show about 1 - 2” of top growth I start to turn the propagator thermostat down by a degree or two every few days. I am now aiming at acclimatising my growing tubers to the air temperature in the greenhouse before potting commences. I pot when the thermostat setting (no LED coming on) is set below the air temperature in the greenhouse for seven consecutive days.
Around the 3rd week in April, when the growing tubers show about 3” of top growth, I select a single growing stem (a break) on each tuber. All other breaks are removed for cuttings. I do this by gently rocking the stems between my thumb and forefinger until they break free of the host tuber and compost. Many of these cuttings tend to have roots attached and these are retained, any exposed cuts (where the cutting has broken from the tuber) are trimmed clean with a sharp craft knife and dusted with a hormone rooting powder (Strike). Dusting is carried out with the powder on my finger, only enough powder is placed on the cut to seal the wound. Where cuttings have no roots attached I trim in a wedge as for a normal cutting ensuring where possible I have an eye. If I require stock of a particular variety I will use surplus vegetation as leaf cuttings.
Note: excessive quantity of powder or dipping will result in rot and failure of the cutting to root.
I place cuttings in prepared (pre-warmed and previously watered in propagator) seed trays or pots filled with soiless seed compost (with vine weevil additive). I bury the bottom of the cutting stem to a depth that just allows the cutting to be supported under its own weight. I then place the trays or pots in a propagator with a bottom heat of approximately 70°F. The propagator is then covered over (4” above) with a layer of horticultural fleece to help retain moisture and provide shading from the sun. Cuttings are sprayed or misted overhead every few days depending on the weather to aid rooting. Rooting takes approximately 4 weeks. During this period the compost should be kept moist but not wet.
Seven days after the removal of the cuttings (this can be late April or early May) and selection of the single stem I commence the potting of my tubers. I pot them into suitable pots – letting the root ball indicate the size of pot, i.e. the root ball should just go into the pot. As a rule of thumb, cutting tubers 3½” & 4” dia pots, adult tubers 5” & 6” dia pots, big adult tubers over 4 years old 7” & 8”pots.
I crock every pot (add weight and provide drainage)as I pot into a soil compost I tend to under pot. This is because it takes longer for the roots to get through this medium than soiless composts. Tuber losses and/or a poor root system can be the result of over potting at this stage and weary growth and small blooms can result later.
The potting compost I use is as follows:
Singletons John Innes No 2 (I have also used Arthur Bowers and Gem with success but prefer Singletons). I use this neat with no additives except for a preventative for vine weevil. Additives result in an out of balance compost the very reason that John Innes came into being in the first place.
Alternatives composts could be:
If mixing your own JI No2 soil compost –
7 parts by volume of fibrous loam, 3 parts by volume sphagnum moss, 2 parts by volume 1/8” grit or Perlite to the bushel. Fertiliser added: 170g hoof and horn or 56g of Nitroform, 170g superphosphate of lime, 85g sulphate of potash and 85g ground chalk OR 425g John Innes Base Fertiliser and 85g ground chalk.
Or for convenience – a proprietary soil-less compost i.e. Singletons, Arthur Bowers, Hortons, Chempak or B&Q.
Note: the British Championship (in Scotland) for cut blooms has only once been won by a grower using soiless compost (George Mc Cormick with help from a soil expert and additives throughout the season). Always select your compost to attain best results as you can waste a full season.
At the end of the month I spray the exterior glass in my greenhouse with Coolglass a proprietary product used for shading. Mixing is to the manufacturers instructions. The consequence of not shading is leaf scorch and subsequent leaf loss which is like torturing the growing plant. I always ventilate the greenhouse on hot days, be aware of the damage that one moments negligence can cause. Take care around this time of year that you are not caught out by a snap frost, but take every opportunity to ventilate the greenhouse, when conditions permit!
Towards the 3rd week of the month I select my exhibition plants (those tubers growing best and strongest) and space them on my staging at 24” centres all other plants are put outside. Following selection I support my growing stems by inserting a plastic 36” cane (this covers all sizes of plants) at the rear edge of each pot and using a thin flat plastic tie material (non-hydroscopic) in a figure eight, tie the growing stem to the cane. I take care when inserting the cane so as not to touch or damage the tuber. The cane is placed behind the pointing growing leaves. Each pot is checked to ensure a label is inserted clearly showing the variety. Do not get these labels mixed up (I usually do)!
After staking I commence foliar feeding using either Maxicrop or Miracle Grow fertiliser at ½ strength of the manufacturer’s instructions to strengthen the plants and aid root growth. I foliar feed every 4 days until the roots reach the side of the final pot. In order to check the root system I turn the pot upside down holding the plant stem and cane in one hand and gently squeeze the pot (plastic) with the other hand until the pot separates itself from the compost. I can then remove the pot and examine the root system. This is easy with practise so be brave and make your first attempt!
Note: I continue checking the root systems of all plants throughout the season. When a plant has a developed root system touching the pot sides I pot on into a bigger pot either 1” or 2” larger using my potting compost. This continues until 10 weeks before the date of the Birmingham Show. As a rule of thumb two pottings take place but I have been known to do three and on occasions I have potted down.
By the end of May or when the cuttings have been in the rooting compost for approximately 4 weeks, they are ready for a move into 4” dia pots and should have a nice root ball. I pot up into soil-less compost. They will remain in the 4” dia pot for the rest of thee season although sometimes I put several cuttings together in 5” dia pots. For the first 2 weeks after leaving the propagator, they are placed between the adult plants on the greenhouse staging, after which they will be placed either outside or into a cold frame until October. If I remember I feed the cutting every 2 weeks with Miracle Grow at full strength. I pinch the growing tip out when they are growing away.
June is usually the month when all the final potting has taken place. I aim for all plants to be in 8” dia pots or above. Occasionally I will use a plant in a 6” or 7” pot but place this inside an 8” pot and add grit. I believe plants are more stable in an 8” pot and the weight of a developed bloom will not topple my plant over with disastrous results.
I continue taking cuttings. As July approaches, the side shoots will start to emerge between the leaves and stems these are available for use as cuttings. Ensure once again the eye at the base of the cutting is intact. On the last day of the 3rd week in June I take my last cuttings and remove all surplus growing basal or side shoots/eyes from the exhibition plant using a sharp craft knife.
In early June ventilation is now a permanent feature in the greenhouse, roof vents, louvre vents and the doors are permanently open. All the openings are covered with a fine netting to ensure flies, moths, birds, animals or insects cannot get inside and cause damage. I damp down the greenhouse floor with a hose each morning as necessary, but never damp down after lunch time, as this causes heavy condensation during the late evening and early morning.
As the plants develop additional ties are made from the stem to the cane. I continually remove all flower buds of a size greater than 1.1 “diameter from the plants as they develop. Note that the first and second flower buds are not a true representation of what can be achieved on later buds, you should only select the third bud or later. I personally aim to flower on the bud between the 4th or 5th pair of leaves as I believe this is where the optimum flowers come from.
July is the month when the buds are selected that will result in the blooms selected and shown at Birmingham. I water plants when required this depends on the weather and the development of the plant.
Birmingham Show is on the 1st week in September and my bud selection commences between 56 days and 37 days before the show date. The show schedule has been obtained earlier in the year and the dates noted, with a view to timing the blooms.
My bud timings are based on a selected bud being 1.1” across the oyster at a time between 56 days and 37 days before the Birmingham Show depending on the variety. For me in my growing conditions Tom Brownlee is 56 days, Roy Hartley 48 days and Yellow Bali-HI is 37 days, all the others are between plus 4 days or minus 2 days from 42 days.
The above timings are, of course, my own, and are not mandatory. Accurate times can only be achieved and repeated by keeping careful notes of the previous year’s experience. I religiously amend my list every year based on the previous year’s results. Even then due to the weather I have been caught out in 2004 and 2005.
My greenhouses are situated 800 ft above sea level and to the West of the Pennine Range in Lancashire, on a good day I can see Blackpool Tower 20 miles away.
All my buds are selected in July any other buds are removed. After selecting the desired bud I pinch out the growing tip of the plant, leaving one leaf intact between the bud and the stopping point. This leaf is left on to help draw the nourishment from the growing medium and any later liquid feed up into the bud. At the same time, as I take the bud, I give the pot a liquid feed of Miracle Grow at full strength. This is my first fertiliser feed direct into the pot and the next one will be 14 days later.
I believe that at this stage my pot has a fully developed root system supporting a strong plant capable of developing an exhibition flower. I also believe that I have grown balanced and that the plants macro systems is not locked and can be stimulated by feeding to produce deep flowers with a diameter of at least 9”. If the macro-system has been locked by previous liquid feeding then exhibition blooms will not develop to full potential.
After pinching out the growing tip the plant stem starts to thicken up and the leaf size increases. The oyster bud increases in size each day, different varieties increase at different rates there is no rule. As the selected bud grows the two side buds male and female show themselves separate from the centre bud. The side buds are removed with either sharp scissors or a decent set of fingernails.
This is the month of plant and bloom development. I continue to ventilate the greenhouse and water the plants as required.
At 28 days before the show I again feed a full strength feed of Miracle Grow this ensures my plant and the root system are fully developed.
Around this period (sometimes before depending on bud size) I place a 9” (I would prefer 10”) diameter polystyrene plate (those used for picnics) with a slot cut in it between the developing bud and flower stem. The husk at the back of the bud is carefully cut off and a figure of eight tie (same material, broad and flat as used to tie the main stem) is attached from the back of the bud to the supporting cane. This will be adjusted around once a week as the bloom develops. (I do not like the wire supports as they tend to mark the bloom back guard petal if not adjusted ever day). The plate stops bloom damage that can result when the foliage rubs against it due to wind or fan ventilation.
At 24 days I commence my bloom feed programme. My first feed is a feed of Calcium Nitrate (15%Nitrogen, 25% Calcium with a quick release) at ½ teaspoon to 1 ½ gallon of water. I believe that Calcium Nitrate helps to rebalance the PH in the pot and also releases the macro nutrients already in the pot., this helps to increase the bloom size to optimum potential.
At 20 -21 days before the show I feed a 1/2 strength feed of Chempak No 4, this is predominately a potash feed (15-15-30) and hardens up the soft growth caused by the previous Calcium Nitrate feed.
Between now and 9 days before the show I liquid feed every time my pots need watering. My feeds at this time (no set pattern as what I feed is weather dependent) comprise, one more Chempak No 4 feed, all other feed are feeds of Potassium Nitrate (13-0-46) with Mono Ammonium Phosphate (12-61-0).
The strength of these feeds varies according to the frequency of feeding and the weather conditions. As a rule of thumb I use ¼ tsp MAP and ¼ tsp PN to 1 ½ gal of water on an average day. However if the weather is sunny I tend towards a potash feed hence more PN than MAP on a dull wet day I tend to a more nitrogen feed hence more MAP than PN. If in doubt continue to use Chempak No 4 at low strength.
9 days before the show I give the plants my last bloom feed, this consists of a full strength feed of a Chempak Zero-10-10 fertiliser or Potassium Phosphate (0-34-52). This contains no nitrogen and is used to harden the blooms allowing transport to the show and the subsequent 3 days of the show. Soft blooms do not travel well.
Throughout this period the greenhouse is extremely well ventilated (on hot days I remove some of the glass) and well shaded (I add fleece shade as required). If it is 80 deg F outside I aim at it being 80 degrees F inside the greenhouse. The doors and vents are open day and night unless it is raining, very dewy or below 55°F.
At the end of the month I expect to see a number of super blooms, as one goes past its best usually another one pops up until there is only the ones left that go to the show. These invariably are not the best grown but you can only show what you have.
September is the month of the Birmingham Show, but it is pointless growing super blooms if they do not arrive at the show in perfect order. To pack them properly is not a five minute job, but a job well worth doing properly.
On the evening before the show (around 24-00 hrs 1st week in September) I select and carefully cut the blooms. To do this I first cut the tie whilst supporting the bloom with my hand at the back of the plate. I cut the bloom stem with a sharp knife with one long very diagonal cut (aim for large surface area so that the transporting lemonade can be drawn up to the flower) and push the stem into an orchid bloom tube filled with lemonade (supermarket as cheap as possible). Blooms are packed in cardboard boxes filled with synthetic cotton wool. The bloom tubes are taped to the bottom of the box. Ensure that the lids cannot come into contact with the blooms,
When staging cut blooms, I use cheap lemonade but a better solution can be made up as follows:-
1 teaspoon of Alum, 1 teaspoon of Milton and 8 teaspoons of sugar to 1 gallon of water, which is placed in the vending machine cups in the exhibition boards. Most blooms should stand for a 3-day show in this solution and still be in a good condition at the end of the 3rd day.
At the show I always get my just reward win or lose, it is absolutely pointless arguing with the judges (you can think it?) who are never biased. I always remember whatever the result that you have good and bad days. If I can’t win (I have had my turn) I like to see others who have suffered and worked long and hard over the year have their day in the sunshine. Remember, to win a championship you have to be a tortured soul. The socialisation of fellow exhibitors is a must and good friendships are formed for life also opportunities for tuber swaps present themselves. It is usually good fun.
On return from the show the cuttings are now important, they should now have 3 or 4 pairs of leaves and all side shoots require stopping with all buds being removed. I try to never let any of the cuttings flower. All I require of them is that they produce a reasonable tuber that will start in the next season.
By the 1st week in September, the cuttings which were taken during April – May will by now be very established plants, and the 4” dia pot in which they were potted should be well and truly pot bound. They will benefit from an occasional weak feed of either Miracle Grow or Phostogen also making sure that they are not allowed to bloom.
If you are one of those persons that tend to grow solely for exhibition, this is the month when we see the last of the blooms, and one can become a little negligent towards the plants. This must not be the case. Continue watering and feeding the plant as normal up to the end of the month. By that time, the lower leaves will probably have turned yellow or even dropped from the plant. This is an indication that the plant is ready to start its run down into dormancy.
At this point, I give each adult plant 1/3rd teaspoon of sulphate of potash, sprinkled on the compost and watered in. I believe that this helps to ripen the tuber as the plant moves into dormancy.
My cuttings are placed on heated beds on my staging with the temperature set at 60°F, I aim to keep them growing until I harvest them in late December and early January. Between now and December I aim to feed every two weeks with ½ strength Miracle Grow.
By the first week in October, all the plants (including those placed outside) are housed in my two greenhouses I start to withhold water from the adult plants, but continue to water and feed the cuttings.
During the day, ventilation is applied whenever possible to reduce the chances of mildew.
Towards the end of October, I cut back the top growth on the adult plants to approx 9”. This assists the plants into dormancy. At this time I start to withhold water from the cuttings, whilst keeping a look-out for rotted plant debris. I remove any fallen debris (leaves and stems), as this will only encourage disease. I check the remaining stems on the tubers frequently by rocking them with my thumb and forefinger. Eventually the stems are all removed and the tuber is exposed at soil level..
This is the month when I harvest the majority of my adult tubers. A week after the plants die back to soil level, the tubers are removed from the compost, the soil is brushed away and the tuber is allowed to dry off for one week naturally on the open staging in the greenhouse. A variety name label is attached to each tuber using an elastic band.
By the end of the month, almost all of my tubers will be out of the compost whence they are thoroughly inspected for rot and any vine weevil grubs, if I find any I cut away and seal the wound by dusting with flowers of sulphur. I squash any vine weevils I find.
I now remove the callous where the stem joined the tuber by prising off using the point of a clean pen knife, some are easily lifted from the tuber, and others take quite an amount of pressure. The open would is dusted with flowers of sulphur or left to dry naturally. It is essential that this is done otherwise tuber rot will result due to moisture left between the stem and scab.
I store my tubers in my loft space aiming at keeping the temperature frost free whilst as near to 34°F as possible. If the temperature is too high the tubers will shrivel. I watch the forecast for nights of extreme frost and always cover the tubers with an old quilt on those nights. Better to be safe than sorry, begonias are expensive.
December is the month when I harvest my cutting tubers. At the end of the month (between Christmas and NY) after the growth has gone yellow and the old stems have fallen away from the tubers, the root ball is removed from the pots. All the compost is brushed away exposing the cutting tuber and its active roots, the scar due to the growing stem is scratched clean with my fingernail. The cutting tuber is then placed on raised net platform 4” above my heated bed and allowed to dry for 7 days only. During the 7 days Wards propagators are filled with 1 part seed compost to 1 part coarse Perlite and watered till just moist. The propagator is them switched on and allowed to warm and dry for 2 days prior to my placing cutting tubers close together on top of the compost (no cover is fitted). The cutting tubers stay on the compost for a period of dormancy and are periodically sprayed overhead with warm water until they start. After they start usually middle of January to late February and show root and top growth they are covered with compost and left to get on with it.
I have found that by treating cutting tubers in this way they remain plump and losses are low as they are not allowed to shrivel. All the heated beds are switched off when the last growing cuttings are removed. The Wards propagators are taken inside. The season has ended, if it ever does.
PESTS, DISEASES AND GROWING PROBLEMS
Without question when you start to grow begonias you think (or hope) that nothing will happen to you. It always does and within a few seasons you will have had everything. Some of these are discussed below with my recommendations.
APHIDS AND WHITEFLY
You very rarely experience this with begonias but it can occur on the odd plant (usually the yellow varieties). It results in disfigured growing tips or small flies on blooms. Spray the affected plants (never blooms) and those around it with a proprietary product. This should not be systemic as begonias do not like systemics.
These are usually found when the buds or blooms are developing. Early evidence is the appearance of notches or holes in petals and minute black balls. The best way to find them is by blowing into the developing bud or bloom and catching them in your hand as they Para shoot or run out of the bloom or bud. When they land in your hand squash them quickly. They run fast.
The weevil is about ¼ to ½” long and is a white grub with a brown head that burrows tunnels and eats its way through begonia tubers. The parent is ½” long beetle that lays up to a 1000 eggs on the surface of the tuber in spring and summer. Prevention is the best course of action, today this is achieved by 3 monthly watering of pots with Provado. To kill the grubs or beetles squash those on discovery this invariably makes you feel a little better whilst you examine the damage they have caused (beetles crunch). One infestation can ruin a whole tuber collection so never skimp on a preventative. Cyclamen, strawberries and conifers are all host plants.
Later in the season when the blooms are developed you can often see black spots on petals. These are the result of fly excrement. The spots can be removed with a damp piece of cotton wool but great care should be taken not to bruise the bloom petals. Be gentle.
Flies should be prevented from entering the greenhouse by ensuring all openings are covered with a fine mesh material.
MOTHS AND BUTTERFLIES
Allowing moths into your greenhouse invites problems with caterpillars. These will damage leaves and flower petals. You must net doors and windows to prevent entry. However moths are clever and can often find ways into the greenhouse that you do not expect. Caterpillar damage is easily identified by holes appearing in leaves and petals. Treatment is by finding the blighter and squashing it. Some caterpillars can be found in small webs that are used to abseil from the leaf when they are moved. Tapping the leaves causes them to drop down to a position where you can squash them. Tally Ho!
I have experienced an infestation of this once in over 25 years however it seems to be a problem for some growers. It can be recognised as distortion at growing tips causing brown brittle leaf margins and brown margins at the edges of petals on flower buds.
These pests thrive in hot dry arid conditions that can occur in the summer months. Prevention is by ensuring that the greenhouse has a humidity of about 70% and also by not taking growing plants obtained from an unknown source into the greenhouse during the growing season.
If you experience an outbreak in mid season do not panic as it can be controlled by removing all growing shoots as they develop and by providing high humidity. However all plants and cuttings where possible should be mist sprayed with Kelthane at the earliest convenience ensuring that the spray does not fall on the compost as this can damage the growing tuber. This chemical is only available from commercial growers. If left unchecked and the plants go dry the pest will spread throughout the greenhouse causing an effect on the plants not dissimilar to the after effects of a flamethrower.
At the end of the season remove all the compost and plant debris from the greenhouse and take it to a tip. Leave the greenhouse open (do not remove anything used in the season) allowing a heavy frost to penetrate for several days. At a later date disinfect all areas of the greenhouse and staging and finish of with a sulphur candle.
Before starting the tubers and during hot water treatment add 10% by volume of Domestos (not cheap bleach) to the water. This kills any mite eggs still alive on the tuber. Remember to wear rubber gloves when using the Domestos.
After this treatment I had no reoccurrence of the dreaded mite.
LEAF EEL WORM
This is a nematode found in unsterilised loam or soil. The thin worm like creatures can only be seen through a strong magnifying glass. The nematode transfers itself from the soil to the growing plant. It can be recognised on leaves when the tissue turns brown to black between the leaf veins (it does not spread outside the leaf veins). If left untreated eventually the whole leaf will turn black and fall off. To prevent only use sterilised soil. If you get it break of affected leaves as soon as you see them this invariably stops it, but be aware this disease can spread from plant to plant by touching and it is a disaster if it finds its way into your propagator on cuttings. Hot water treatment at the beginning of the season ensures that upon tuber start up you are free of the pest. The only other treatment is by chemical means practised by professional horticulturalists, personally I would rather throw the plant than use the dangerous chemicals involved.
Again presentation is the best treatment this can be done by providing adequate ventilation and by ensuring your plants are never dry. However most people get mildew at some point. Be aware that once it starts it spreads quickly so do not dally. It can be recognised by the appearance of white powdery marks on the leave a little like cigarette ash. If left the spots rapidly increase in size. The best treatment I have found is to spray with Bio Systhane that can be purchased at most garden centres. Please note that most mildew sprays do not work but this one stops mildew instantly. A down side is a white stain left on the foliage if this concerns you wipe with cotton wool dampened with milk.
STEM ROT (BOTRYTIS)
This is recognised on the stem by a wet brown patch that if left will spread throughout the stem and into the tuber. It is usually caused by overfeeding or by inadvertently touching the stem with the watering can causing bruising. There are many theories of how to deal with stem rot all of them involve cutting away the affected area. None of the theories work. The cure for this was found by the late Dan Ramage and involves using a fungicide call Rovrol that is often used by orchid growers (supplied by orchid nurseries on request). You mix the Rovrol with water and spray on the affected area (do not cut or wipe the rot away). After a day a hard skin forms around the affected area. The plant can then continue to be watered and as before.
OEDEMA AND LEAF DISORDERS
In the early season between March and May growers often complain about distorted or yellowing leaves these are often the result of taking begonias out of heated propagator and moving them into a cold environment in the greenhouse. This is a bit like having a bath in January and going to stand outside all night in the nude. I would go yellow and distorted never mind the plant. The penetrative is gently acclimatising plants to the environment in the open greenhouse. If you experience this do not panic it invariably grows out as the plant ages.
Later in the season oedema can be experienced on the under side of the leaves.. Examination of the marks shows that the surface of the leaf is pitted and has a shiny corky crust. . This is caused by atmospheric humidity on cold nights and damage although recognised can be ignored as later leaves will come clean as atmospheric conditions improve. Paraffin heaters in greenhouses can cause similar symptoms.
Later in the season greenhouses than have inadequate shading will result in growing begonia plants suffering from leaf scorch caused by sunshine. This results in brown patches appearing on leaves indicating burnt tissue. Prevention is obvious, ensure adequate shading is provided. If you are to late break the affected leaves of and replace with the side shoot that will grow at the leaf axils.
Sometimes a plant will throw a foliar petal this is a flower bud that thinks it’s a leaf. It can easily be recognised as it is often a combination of both a leaf and a flower. Where experienced this bud should be removed.
At the end of the season the yellowing of leaves indicates that the tuber is spent and requires a rest. This is normal and the treatment is to gently take the plant to dormancy by withholding water.
This is a problem that inexperienced growers often have and is caused by under or over watering. Rapid changes in day and evening temperatures can also cause this. The cure is to learn to water correctly (not easy) and to ensure that some heat is available in the greenhouse for those cold nights (aim at 60 deg F.
MY FAVOURED CUT BLOOM SHOW VARIETIES
These are in my opinion the best varieties for exhibition at the current time:
Tom Brownlee raised by the late George Mc Cormick, on its day unbeatable, very deep and up to 10 ½” in diameter, Linda Jackson raised by the late George Jackson, must be shown young due to its enormous open style when aged and my own Robert Tyler Murphy, named after my son, the best of this is yet to be seen on the show bench.
Avalanche the best one but soft petal and is only at its best for a couple of days and Glenfarg raised by my mentor Bertie Cruikshank, the only white with leather petal, long lasting with a rose bud centre.
Monica Bryce this is really a lemon (as of yet no true yellow available) but its form (the best) and shape are excellent. Raised by my brother and named after my late mother. I think of her when I see it with awards at shows.
Falstaff, the best when not blotched or diffused and Mrs Dan Ramage raised by an old deceased friend that was John Hamilton’s mentor, huge a little flat and always susceptible to stem rot.
Nicola Coates raised by Dave Coates from Southsea, big and deep but not always round. As it get older loses its shape. I particularly like this one.
Roy Hartley an old timer over 30 years old, when its good it is deep and full but I find the colour insipid, Powder Puff raised by the late Harry Bridges almost shell like in colour always good size and shape but can lack depth and Sweet Dreams, definitely one of my favourites and the most reliable, I particularly like the sharp colour and wavy petals.
City of Ballaarat, the best of its colour when not blotched a true orange, Mary Heatley an old favourite that easily grows to 9” and above with a multitude of petals and Westlawn Tango, raised by Derrick Foster in Ipswich, good form and shape a little insipid in colour. I think Colin Hamilton raised by John will also be a winner; I like the form and colour?
Barbara Bryce raised by brother and named after his wife, solid picotee with a good edge when grown in good light, I struggle to get above 8 ½” but form and number of petals is excellent and Ruby Young raised by the late Rob Young, I have grown good ones but can blotch for no apparent reason and a little susceptible in form.
Yellow Bali Hi the only reasonable one, soft petals lacking and depth (very rarely get one deep), petals that edge very easily in strong sunshine. At its best a show stopper that adds colour and dazzle to a board.
Mrs E McLauchlan, for form almost unbeatable but blooms above 8 ¾” are rare and only obtained from large tubers and Beryl Rhodes again excellent form and colour. Both raised by the late George Mc Cormick.
All varieties without raisers name are Blackmore and Langdon varieties.