Perennial

Perennial, annual or biennial?

Plants are often grouped by how long they live. A perennial lives for several years, coming back season after season. An annual completes its whole life in one year — it germinates, flowers, sets seed and dies (lettuce, courgettes and most beans work this way). A biennial sits in between, growing leaves and roots in its first year and flowering, seeding and dying in its second; carrots, parsnips and onions are biennials we usually harvest in year one, before they run to seed.

Knowing which is which saves disappointment. You resow annuals every spring, but a perennial is a one-off planting that earns its keep for years.

Edible perennials worth growing

The UK has plenty of productive perennials, and they're some of the most rewarding crops for beginners:

• Rhubarb — a single crown crops every spring for a decade or more. You can even bring an early harvest forward by forcing it under a bucket.
• Asparagus — slow to establish (two to three years), then it produces tender spears each April and May for up to 20 years.
• Fruit bushes and trees — blackcurrants, gooseberries, raspberries, apples, pears and plums all crop year after year once planted. Many raspberries spread by sending up a runner-like sucker nearby.
• Herbs — rosemary, thyme, sage, chives, mint, oregano and bay are perennial, so one plant supplies the kitchen for years.

Some familiar herbs, though, are not perennial: basil, coriander and dill are annuals you sow fresh each year.

Why perennials are low-effort

Once a perennial is established, the hard work is done. There's no annual sowing, pricking out or hardening off — the plant simply wakes up and grows. Their deeper, established root systems also cope better with dry spells, and a yearly mulch of compost is often all the feeding they need. For a small or busy plot, a few well-chosen perennials give a lot of food for very little fuss.

UK overwintering notes

Most hardy perennials die back as the days shorten, leaving bare soil from late autumn. Don't panic — the roots, crown or woody framework are alive underground or above it, and growth restarts in spring. A mulch over the crown in autumn protects against hard frosts and feeds the soil for next year.

A useful exception is the tender perennial: a plant that's perennial in a warm climate but can't survive a UK winter outdoors. Chillies, aubergines and many salvias fall here. We usually grow them as annuals — sown each spring and discarded after fruiting — though you can overwinter a chilli plant on a frost-free windowsill and crop it again the following year.

Want to plant some? Browse the fruit growing guides and herb growing guides to get started.