Biennials are best after a winter rest | In Fiona's Garden

This is because of their growth pattern.

An annual grows, flowers, sets seed and dies in one season.

A biennial, on the other hand, grows a stem and leaves in its first summer, pauses during winter and then flowers and sets seed in its second summer.

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Most of us are familiar with the silver dollar plant, aka honesty (misleadingly named Lunaria annua), with purple or white flowers followed by large, round seed pods resembling mother-of-pearl.

If you've grown it for any length of time you've probably noticed that there are always plants sitting around in summer which don't flower until the following year.

This is because they've germinated but need to over-winter before coming into bloom.

Colder weather is the key, telling the plant to pause growing until the days start to lengthen and warm up, when it can flower and set seed.

Canterbury bells, forget me nots, foxgloves, hollyhocks, Queen Anne's Lace (Amni majus) stocks and sweet williams (Dianthus barbatus) are all biennial (or sometimes short-lived perennial).

Nurseries often sell punnets of biennial flowers but, maddeningly, nearly always in spring.

This is confusing for novice gardeners because however well the seedlings are cared for, they won't flower until the following year.

This isn't the gardener, it's in the plant's DNA to wait for a cold spell before it can get going again.

Most of my biennial flowers have been here for years and self-sow though I'm always looking out for anything new.

This year it was an unusually pretty False Queen Anne's Lace (Amni visnaga) with dome-shaped flowers that lasted for weeks indoors.

But it's biennial vegetables that are on my mind in January.

Many of my favourite vegies are biennial, including beetroot, carrots, Brussels sprouts, cauliflower and broccoli.

These are eaten either after their cold-weather phase but before they flower - the roots of beetroots and carrots, the leafy buds of Brussels sprouts - or as their flower buds develop, the part we eat - broccoli, cauliflower.

Cabbage, celery, leeks, onions, parsnips, swedes and turnips are also biennial and the parts we consume - whether it's the roots, the stalks or the leaves, lose their flavour and become largely inedible after the plants have bolted into flower.

Broccoli and cauliflower are the two I need to soon if I'm to harvest them this winter, as they need to be well established when the cold weather hits us in April.

This will halt their leafy growth but tell them to start flowering after mid-winter as the days lengthen and become warmer.

The seeds are big enough to sow direct but I'm start mine in seed trays in the laundry as we're still experiencing the odd cold night (down to single figures again recently).

I'm hoping to plant the seedlings in February and if all goes well, harvest in July.

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