Cleaning And Trimming Begonia Tubers

Most growers dry off their begonias at the end of the season, then clean and trim them before storing in sand or dry peat over winter. I have always had a problem with cleaning and trimming my begonia tubers before winter, and I don't store them in anything.

TUBERS EXTREMELY BRITTLE
I find that begonia tubers are extremely brittle, especially when full of water at the end of the season. If I could dry them off at this time, fine. But I can't. Mine just don't seem to want to dry out before the frost (even more so this year). So they survive the winter surrounded by damp compost. I could force the issue by prising away the old compost, but if the tuber is damaged there is a greater risk of fungal infection getting hold and destroying it. So I have found it best to wait till planting time.

CLEANING REMOVES PESTS, ESPECIALLY VINE WEEVILS
You saw last year how vine weevil larvae overwinter with begonia tubers. Vine weevils love containers, and, unless treated with insecticide (e.g. 'Provado Vine Weevil Killer') will hitch a ride into storage. Unless these larvae are spotted and removed before new growth starts, they will play havoc with young tender roots, thereby destroying the plants.
Cleaning the tubers helps us spot and remove any unwanted pests, especially vine weevils.

Propagating the tubers for a week at low humidity has dried off the tubers nicely, thus making them easier to clean. It has also ensured dormancy has been broken, and has revived any overwintering pests. Now we can risk breaking the tubers during cleaning, since if damaged they will not be as vulnerable.

A GENTLE BRUSH AND SHAVE IS ALL THAT IS REQUIRED
After gently brushing to remove old compost or soil, the old straggly roots can be trimmed off. This will help water get to the tuber and will induce branching in the new roots (roots behave like stem tips when removed).


PLANT THEM THE RIGHT WAY UP
In the case of old tubers, it is easy to tell which way up to plant them, since the old stem scars and roots provide clues. However, new tubers from the garden centre can be confusing. There is a great temptation to plant them upside down.

Remember that the hollow side is the top. If you look carefully, you should be able to see the old stem scar; the new stems will develop from buds around this scar.