Begonias sold in bedding trays usually go on sale around mid-April, and the Non-Stop and trailing varieties sold in single pots follow a few weeks later in early May.
But this doesn’t mean they are ready to plant straight into your garden. Most people who are buying bedding plants when they first become available are planting up pots and hanging baskets and keeping them under cover until the danger of frost has passed, this is usually the end of May depending on where you are located in the country.
Begonias like most summer bedding plants are native to subtropical and tropical climates. So here in the UK, the bedding begonia which is used mainly for borders is classed as a half-hardy annual. Which means they are raised for a summer display and live, flower and die in a single season.
The Non-Stop and trailing begonia are classed a half-hardy perennial, so if you lift the tuber in autumn and store it away from the wet and cold during the winter you can replant them in spring and they’ll flower in the summer.
Types Of Begonias
Begonias are divided into two main groups:
Just like busy lizzies the fibrous-rooted semperflorens begonia was regarded for a long time as a house plant rather than a summer bedding plant.
Now the fibrous-rooted begonia can be seen everywhere in borders, containers and hanging baskets.
One of the main reasons for its popularity is that just like busy lizzies they can be used as a source of bright colour in shade and under tress from early summer until the frost hard frost in autumn.
The fibrous-rooted begonia is usually sold in a 6 pack bedding tray making them a more economical choice for a bedding display. Where the tuberous begonia is sold in single pots and is mainly used as a container or hanging basket plant.
As the name suggests tuberous begonias grow from a tuber just like potatoes. A tuber is an enlarged storage organ that grows beneath the soil surface. During the summer months, it stores energy to allow the plant to grow again the following year.
Tuberous begonias produce larger showier flowers than the fibrous-rooted begonia and come in a dazzling range of colours, and the trailing varieties of the tuberous begonia are one of the most popular hanging plants too.
Where To Plant Begonias
Fibrous-rooted begonias thrive best in humus-rich soil and partial shade.
Tuberous begonias need a soil that is rich in organic matter with little or no lime present and thrives best in light shade.
How To Grow Tuberous Begonias
- If you plan to raise begonias from a tuber then they are usually available from January through till late April.
- When purchasing tubers you’ll often see the first signs of new shoots growing from buds.
- Tubers should be kept dry and frost-free until you are ready to start propagation.
- You’ll need to plant your tubers in a pot roughly double the diameter of the tuber.
- Fill the pot with a moist sandy potting compost about 2 inches (5cm) from the top.
- Begonia tubers are quite strange looking and have a hollow side which is the top of the tuber and a rounded side which is the bottom.
- Place the tuber rounded side down and gently push into the compost, fill the pot to the rim with compost and water in.
- Begonia tubers need an initial bit of heat to get them going. Put the potted up begonias into a warm environment, a propagator is perfect or you could even place them on a window sill.
- They should start to shoot within a couple of weeks, and as soon as you’ve got about two inches of growth you can take off the lid of the propagator.
- Move the pots into a bright, frost-free light place, keeping them moist but not waterlogged until they are safe to plant out in the garden.
How To Grow Fibrous-Rooted Begonias From Seed
- You can sow begonia seeds from January to March under glass, polythene or in a propagator, keeping them at a temperature between 21-24°C (70-75°F).
- Sow seeds thinly in trays of seed compost, water the compost before placing the seeds in the tray as watering after may wash the seeds away.
- Do not cover the seeds with compost as light is required for germination.
- Seedlings should appear in 2-3 weeks, and remove the cover when they do appear.
- When large enough transplant into trays spacing them 2 inches (5cm) apart and continue to grow them on at a temperature around 15°C (60°F).
- Stand out for a few days in mid-May avoiding frost and transplant into their final position in early June.
Regular watering is important for healthy begonias. The soil should remain moist at all times, but not too wet, as this can cause rot.
Water at the base of the plant to keep the foliage dry and prevent leaf spot and fungal diseases.
Feed your begonias every two weeks with a general-purpose fertiliser with the rest of your summer bedding plants.
Begonia tubers should be lifted before the first hard frosts in autumn.
Their leaves will begin to yellow naturally at which time watering should be reduced.
Dry tubers should be stored in barely moist soil or sand in a frost-free place and watered occasionally to prevent shrivelling.
Foliage may scorch in the hot sun.
Flower drop may be a sign of over-dry compost.
Begonia tubers may rot in over-wet conditions, make sure compost is well-drained and stand pots on pot feet to help prevent waterlogging.
Tuberous begonias may suffer from powdery mildew or fungal leaf spots.