Preventing Tuberous Begonia Stems Breaking

Tuberous begonia stems can be extremely brittle and easily break off where they join the tubers, especially when knocked or rocked by high winds. Discreet staking gives support and helps prevent this.

Take care when inserting the cane that you do not damage the tuber. I usually insert them at an angle, so that the base is well clear of the side of the tuber. The stems can then be tied quite loosely (though with a slight tension on the stem), allowing room for stem thickening. As the plants grow, either insert more stakes as necessary, or replace with longer ones.

Feeds too high in nitrogen gives long growth, making the foliage top-heavy. Using high potash feed will both harden the tissues and produce shorter growth. It will also help flower colour and numbers. You don't need much - just one or two feeds will do. Tomato feed is high potash. But I always use 'Phostrogen' with every feed. However, although this produces wonderful plants, they still need staking, but not so much.

MAKE A SHOOT TIP CUTTING FROM THE OLD STEM
Provided you get to the broken stem in time, you can make a shoot tip cutting as shown in earlier posts, either using compost or perlite and water. Cut stem under water (to prevent air bubbles) about 6mm (1/4 inch) beneath a node. Then leave in water for about 4 hours. Some growers actually root in water, though I have never tried this - except for perlite and water, which seems to work well and was outlined recently.

The problem with begonias is that they only grow very slowly. So best to remove all flower buds on new plant, to give the new tuber as much chance as possible to develop before winter. I would again use 'Phostrogen' to produce good growth of both leaf and tuber.