THE CULTIVATION OF PENDULA BEGONIAS
By Bert Weir
Pendula begonias have long been favourites of the gardening public, and with justification. A pendula begonia on display at a flower show and bearing a profusion of flowers is a sight to cause great admiration to all, and in particular gives the grower tremendous satisfaction. They are grown mainly in hanging baskets where their pendulous habit can be displayed to great effect, but can equally be grown in any of the modern containers now available. Although the culture of the pendula begonia largely follows that of the large flowered hybrids, there are certain key differences that if followed, will ensure a specimen plant fit for the show bench.
The key areas of difference in culture between the large flowered hybrid and the pendula are as follows;
a) If the plant is to achieve its full potential it is desirable to start the
tubers into growth approximately one month before the normal starting date for the large flowered varieties. Provided a propagator is available an ideal starting time is mid-February. Do not despair if you do not have a propagator, a later start will still produce a satisfactory plant, but remember the aim is to produce an exhibition quality plant, hence the early start.
b) Whereas the number of shoots produced on the large flowered hybrids is generally restricted in many instances to only one, on the pendula tuber all shoots produced should be allowed to develop.
c) To enhance the beauty of the plant during the flowering period, both male and female flowers are left on-remember it is the mass of flowers that is important, and not the size or form of individual flowers.
The principal objective is to develop as many stems, and consequently as many flowers as possible, since it is the weight of flowers produced that pulls the stems over the side of the container to produce the pendulous effect. The question is often asked: "How
many tubers per pot?" if you are growing for a particular show. It is then important to check the show schedule and stick strictly to the number specified. The recent trend in show schedules is to refer to a pot or basket of pendula begonias, which suggests there is no restriction in the number of tubers per pot. In practice, as with all other species, the determining factor is the size of the tuber in relation to the container size. An ideal arrangement with tubers of approximately two to two-and-a-half inches diameter is to grow three plants
of the same species in a triangular arrangement in a six to seven inches diameter container. If you have one large tuber of four to four-and-a-half inches diameter, then it will generally be found better to grow only one plant in a container of the same size. Remember pendulas do tend to be very vigorous in growth and consequently require plenty of room to develop.
As stated previously the tubers should be started into growth as early as practical. Place them in plastic seed trays in a 50/50 mixture of peat and sand, or alternatively any of the commercial mixtures of soil-less seed compost, and water them well in, using a fine rose on the watering can. Place them on the bench or propagator with a bottom heat of 65/70 F. If placed on the open bench try to maintain a minimum air temperature of 50 F. After approximately three to
four weeks in the starting medium the tubers will be well established with a good root system and at this stage they should be transferred to their final pot or basket and planted in a potting compost of your choice, J. 1. No. 2 if you prefer a soil based mixture, alternatively any of the commercial, soil-less types of potting mixtures, which are now used extensively, will give good results. Another, well tried compost is to mix the Chempak base potting mixture. This is becoming increasingly popular with many growers.
When the plants have established in the potting medium the growth will be fairly rapid. When the stems are approximately six inches long the first flower buds will start to appear and at this stage cut all the stems back to below a leaf joint showing an eye. The eyes in all of the leaf joints below where you made your cut will now grow on and you will have three to four shoots where previously you only had one. At this stage your plant will look pretty sorry for itself but do not worry the plant will soon recover and the new side shoots will develop at a fairly rapid rate. When the side shoots show buds, nip out the growing points; this will induce a further lot of side shoots, which are the ones, which will produce the flowers. If you are growing for a specific show date allow between five and six weeks for a bud approximately ¾ inch diameter to reach full flower. Pendulas are rather more forgiving than the large flowered hybrids in respect to timing, so do not worry if you do not get it right first time note carefully the stopping times so that you can make the necessary adjustments the following year.
Pendulas when in full bloom do tend to be fairly gross feeders, but in general, the feeding programme is similar to that for the large flowered hybrids. Commence feeding after the stems are cut back using a high potash fertiliser of your choice. Two popular types being Phostrogen or Maxicrop but any fertiliser with a high potash content will be equally satisfactory. Do not exceed the manufacturers' recommended strength as this can generally be taken as the maximum strength for plants in full growth with vigorous root systems. Do not be tempted to add a bit extra, you are likely to do more harm than good. It is much safer to feed twice using a half strength solution than to feed once at full strength. Watering is one of the areas with which many growers find difficulty, particularly when using plastic pots, as it is one of the most important, yet difficult operations in the cultivation of any plant and in particular the begonia. As is well known plants absorb air as well as water through their root system and if the compost is kept constantly moist air will be driven out, and the roots will rot. The best advice is to give the plant a good watering preferably from the top and then refrain from further watering until it becomes dry again. Plants with weak root systems are particularly vulnerable to over watering. The best advice is: if in doubt-don't. Remember most plants are ruined by over watering.
It takes approximately six months from start to finish to produce a plant in full bloom, so it is now time to sit back and enjoy the fruit of your efforts. Do not be tempted to take short cuts during the growing period; any attempts to do so will be reflected in the final quality
of your plant. The advice given has been well tried and tested, and if followed will produce a plant that will give great satisfaction and hopefully make all the effort worthwhile.
Pendular Begonia Varieties
Champagne – Belgian variety imported and distributed in UK by “Taylors LTD”. Cream coloured . Very free flowering . Available from good garden centres.
Firedance- Blackmore and Langdon variety. Bright orange with deep orange centre. Large flowers.
Lou Anne – Antonneli Bros America. Clear pink. Natural pendula habit with long flowering stems.
Pink Cascade – Blackmore and Langdon variety. Large pink flowers. Compact upright grower.
Mrs Bilkey – Very old variety (approx 100 years) very difficult to obtain now. Orange colour. Extremely free flowering with a natural habit.
Orange Cascade – Blackmore and Langdon variety. Soft orange colour. Very large flowers with a good pendula habit.
Isobella origin - Bill Squibb (uk amateur) Lemon colour. Very free flowering with large flowers