Growing advice - Begonias

Begonias were first discovered by a Spanish explorer in 1651, but it was a French botanist who studied and named them after the then governor of Haiti, Domingo Michel Begon. The begonias we grow today are often far larger and showy than the ones first seen. Begonias can be grown in pots, baskets or as edging in more formal displays. The main types generally fit into one of three types: The large flowering types growing from 20 - 45cm (8 - 18in). They include singles and doubles and come in a whole range of colours including red, pink, salmon, yellow and white. The Pendula types have small single and double flowers on long trailing stems. They are ideal for flower pouches, tubs or window boxes. The Multi-flora types are smaller at 15 - 25cm (6 - 10in). They have masses of double flowers and come in colours of pink, red, salmon, yellow, orange and white.
How to Sow for Best Results

Begonia seed is very tiny and fragile, almost as fine as dust, and can be difficult to handle. Try to avoid crushing or touching the seed as this can cause damage. The seeds should look like dust or pepper when you sow them, if not they may be damaged. The best way to sow them is to carefully cut open the foil and then pour in a teaspoon of dry silver sand on top. Carefully shake the sand to mix it in with the seed, and then sow direct from the packet, slowly tapping it to release the mixture over the surface of the compost. Do not cover the seed with compost. Sow from early February to late March. Sowing earlier will not give you bigger, better or earlier flowers. The plants will form, in some cases, root tubers instead of leaves and flowers!

The compost should be moist, but definitely not wet. Wet compost (which can even be the case straight from the bag) will be cold and reduces the oxygen that the seeds need to germinate. It may even stop the seeds germinating at all. If the compost is too dry this will also cause problems. If this is the case, sprinkle a small amount of warm clean tap water over the compost and leave it to soak in thoroughly. When the compost has absorbed the water, take a small handful and squeeze it in your fist; if water drips out it is too wet, so leave it for a short while in a well ventilated spot to dry off. If it holds together when you open your hand, it's just about right. You can now fill your seed tray or pot with the moist compost and you don't have to water it again before you sow the seed.

The compost surface should be firmed and level. Seeds that fall down surface cracks may fail, as the seed's food reserves are so small, and the plant can't produce the required growth to reach the surface. After sowing your seeds, don't cover them, as they need light, oxygen, neat and water to grow well. Place the tray or pot inside a clean, clear plastic bag and seal with an elastic band. This will hold in the humidity and heat. Then place the tray or pot in a brightly lit place, but not in direct sunlight.

The soil temperature is critical for good germination of begonias. It has to be high, between 24C- 27C (75F - 80F), but only until the seed has germinated. The temperature must not fluctuate as this can cause poor or failed germination. Germination should take about 2 or 3 weeks. The bag can then be removed and the temperature should be lowered to about 20C (70F). In a cold year or if you live in a cold area, it would be advisable to wait a few weeks before sowing, as the seed may die if left in wet and cold conditions. Check the compost for dryness regularly. If this is the case, add a little clean water from below, being careful not to over water. Too much water can kill seedlings, as it can spread "damping off fungi" and encourage other moulds and diseases.

When the seedlings are large enough to handle, (this should be after about 5 - 6 weeks), without touching the stem, just handling the leaves, transplant them carefully either separately or in small clumps (depending on the variety) into 7.5cm (3in) pots. Grow on in a cool, frost-free, well lit place, but again avoid direct sunlight. To ensure really well branched plants, pinch out the growing tip after they have rooted well into their pots. Finally, pot them on into 15cm (6in) pots or baskets, (depending on the variety, or where you want them to end up) and grow them on for a few weeks in a frost-free greenhouse or similar. Gradually acclimatise them to the outside conditions by placing them in a sheltered place during the day and bring them back inside at night. Watch out for cold winds as well as pets, birds, mice etc. After all risk of frost has passed they can be left out or planted into their final flowering position for you to enjoy.
Pests and Diseases

Begonias are generally pest free, but still keep a eye out for greenfly/aphids and if they become a problem, use a recommended proprietary brand of insecticide. Water the plants regularly and feed with a general all-purpose fertiliser. Don't forget to deadhead and remove any damaged flowers or leaves. This will help reduce the spread of any pest or disease that may arise.
Over Wintering Begonias

Begonias are frost tender so if left outside in the winter, they will quickly die. Before the first frost, lift the plants with a little soil around the roots, place them in a seed tray or similar and dry them off in a frost-free shed or bright garage. They must have good ventilation and be left without water to die back naturally. Keep frost free and look forward to the spring when you can start them off again.
Tuberous Begonias

The begonia tubers should be stored in a cool, dry, frost free place until March when they can be planted in trays of moist general purpose compost about 7.5 - 10cm (3 - 4ins) deep with the tuber just below the surface. They should be planted with the hollow side up and kept at a temperature of about 18C (64F). Keep them in a brightly lit place but not in direct sun light. When shoots start to develop they can be carefully potted into 7.5cm (3in) pots and as they get bigger re-pot again into 15cm (6in) pots, flower pouches or baskets.

As with the seed raised begonias, gradually acclimatise them to outside conditions by placing them in a sheltered place during the day and bringing them back inside at night. Watch out for cold winds as well as pets, birds, mice etc. After all risk of frost has passed they can be left out or planted into their final flowering positions.

Garden Shopping Centre