Tuberous begonias easy to start indoors

If you want plants in your garden that put the brakes on anyone passing, grow tuberous begonias.

They’re one of my favourite plants as they’re easy to start indoors, easy to grow, and trouble-free in the garden.

They look especially good in hanging baskets and planters on the shadier side of the house.

Don’t confuse these with the smaller wax leaf begonias, the annual plants often seen edging flower beds. They’re the ones with shiny green or bronze leaves and pink, red or white flowers.

Tuberous begonias can become large plants, especially if they’re saved from year to year.

Most of the ones we see for sale in flower in spring are small ones grown from cuttings, although they will sometimes develop a small tuber by the end of the season.

The ones I look out for come in a far wider range of colours and forms. Blooms can be single or double, with or without lacy edges. T

here are upright forms and pendulous ones, and some have flowers that look like large camellias. Begonias originated in the shaded protection of tropical and subtropical forests, so they’re perfect for lighting up darker corners, yet they can take early morning or late day sun. The ideal would be dappled shade.

By starting them now they’ll be blooming by the time I’m ready to move them outside at the end of May, or when I’m sure there’ll be no more frost.

They’ll continue to bloom until the first frost of fall. Begonias have both male and female flowers on the same plant. The smaller one with a single blossom is the seed producing female.

The male is the larger, double flower. I don’t bother, but some growers pinch off the female flower at the bud stage to direct energy into the male for a larger bloom.

I plant the tubers, which sometimes look like hairy potatoes, in 100 mm to 150 mm pots — that way they only need to be transplanted once into their summer home. For this I use a light, well draining potting mix.

One that stays soggy can cause rotting before the tuber has a chance to sprout.

Unlike potatoes, which are also tubers, you can’t cut begonia tubers into pieces to produce more plants.

It’s important here to determine which side is up as, unlike many spring bulbs that have a clear pointy end and will still manage to grow even if planted upside down, begonias won’t do well.

The top side is the side with a depression, even concaved, except it isn’t always obvious. The rounded base will sometimes have a few residual roots.

Don’t bury the tuber completely. I only add a sprinkling of soil over it.

Plant it too deep and it may not sprout. After it does sprout, and it can take a couple of weeks, more soil can be added.

I grow mine under lights, but they can be placed anywhere with good light, but not in direct sun, and a constant temperature of around 21 degrees Celsius.

Don’t allow the soil to dry out completely nor be constantly wet, and don’t let it collect in the depression. In the early stages, a clear plastic cover will keep the moisture in.

As sprouts appear and begin to grow, the trick is to nip them off leaving just two or three to grow on.

This will ensure all the stored energy will go into these main stalks. Begonias can be pinched out or cut back at any time to encourage a bushier plant.

Don’t forget to fertilize, especially if your potting mix has no added fertilizer.

Spring, will it ever stop starting and stopping? •••

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