How to divide begonia tubers

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Tuberous begonias will come back year after year, and with every passing season, the tubers will grow in size. Once they are getting quite large, you may start to think about dividing them down and creating new plants. Just be aware though, that new, smaller tubers will not provide as many flowers as older larger tubers will.

How to split the tubers

Splitting begonia tubers is relatively straightforward, although I must warn you that freshly cut tubers are more vulnerable to rot and infection, so the process is not without risk.

Step 1 – Find a suitable tuber.

Tuber to be divided

A tuber ready to divide should be large and also have at least two clear stems. Please note the tuber I split here in the images is nowhere large enough to need splitting but it is all I had on hand to demonstrate with!

Step 2 – Cut with a sharp knife.

tuber cut in half

Cut the tuber with a sharp knife directly between the two stems.

Step 3 – Leave to dry.

tuber in sunny spot

Now I like to place the tuber on a piece of kitchen towel and leave it in direct sunlight for a couple of days. I find this helps to start the scabbing process on the cut and thus reduces the chance of disease and infection.

Step 4 – Replant.

Now I replant the tuber on the surface of some good, high-quality compost.

Do I need to sterilise?

No, you don’t need to worry about sterilising either your equipment or the tuber. I would however say it is important to use a clean knife to cut the tuber as you don’t want to be introducing any bacteria or fungus into the fresh cut.

It is recommended though to dust the cut with a fungicide which should help to keep the cut tuber healthy. You can use the product below and just give each cut side a light dusting.

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Grow Mate Tricho Protect Trichoderma Harzianum (400 gm)
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 It is effective in controlling both seed and soil borne pathogens, causing damping off, root rot and wilt diseases.

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03/01/2024 03:49 pm GMT

Alternatively leaving the tuber in the sun for a few days should allow a skin to form which will also help to protect the tuber.

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  1. To promote your site, why not give me your details and I’ll put it on Facebook page Growing your own plants from cuttings?

  2. Begonia bulbs do you use something to sterilise and clean old ones before cutting pls help.

    1. Hi Angel, you don’t need to sterilise before cutting. Many people do recommend dusting the cut with a fungicide after it has been cut. Something like this will do the job:

      You can just leave the tuber on a piece of paper and allow a skin to form which is usually all they need, although the fungicide is the more prudent option.

  3. I divided my yellow tuberous begonia into two pieces and gave one to my daughter they are now flowering but mine has big yellow flowers and hers has much smaller red ones, how did I do that?

    1. I have no idea! I have heard about red begonias becoming paler and more pinkish over time but never heard of them completely changing colour before from being divided!

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