Gardening | How to get the best from your begonia tubers, with Brian Kidd

Tuberous begonias are one of the most popular plants to enhance the summer garden or greenhouse.They have just arrived at most garden centres as dry tubers in packets with a pretty picture on the front.

Saturday, 15th February 2020, 6:00 am
Begonias grown from tubers
Begonias grown from tubers

They are not cheap but if you are like us, we buy a couple each week starting as soon as we see them and in a few weeks you will have a wonderful selection of colours.

Begonia tubers can be started into growth at any time from now onwards.

If you only decide to buy one, perhaps for growing on a light windowsill, simply fill a five-inch diameter flower pot with any loamless compost.

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Make sure the tuber is the right way up and push it into the compost so that it is half-buried.

Give the compost some water and sit back and wait for the shoots to appear.

Begonia tubers have a rounded base with a rim and a sunken area on the top.

If you look carefully you can see where the scars from last year’s flower stems were.

If you are going to plant quite a lot they are best started off in moistened loamless compost, in seed trays in the light in a frost-free greenhouse.

Or, for quicker results, you can do this in a greenhouse with a heater or in a plant propagator.

The idea is to have well-established plants which will be in flower by the end of May.

Fancy getting two for the price of one? After all, we enjoy a bargain.

This might seem a little rash but you can propagate tubers by cutting them in half when the shoots are about half-an-inch high.

Just use a sharp knife and cut through the tuber so there is a shoot on each piece.

Is there any risk? Will that cut lead to tuber rot?

There is little risk if the cuts are dipped in sulphur dust.

The only thing to remember is that the tubers are normally round but if cut in half they will never grow into a round shape again, but this really doesn’t matter.

So, we have two for the price of one and both parts of the tubers will produce pots of leaves and flowers and you would never know about that operation!

Once the tubers have a nice fibrous root, each one should be potted into a three-inch diameter pot and grown on until the third week in May when they can be safely planted out into the garden – once the danger of frost has passed.

If the plants are intended to create the most superb greenhouse effect, they should be re-potted intofive-inch diameter pots once the smaller pots are full of roots.

What about feeding?

Feeding with liquid fertiliser for tomatoes commences once the pots are full of roots and a feed every two weeks is the best option.

Begonias adore sunshine in well drained but moist compost and will flower all through the summer right up until the frosts arrive.

There is nothing to match an adorable tuberous rooted begonia.


Check all indoor plants to ensure there are no whitefly around. If you see any, squash them and rub off any eggs which you will see on the backs of leaves. This simple advice prevents a build-up of thousands of the little blighters.