How to save your own veg seed

Self-pollinators like beans and tomatoes are easiest, as they always produce seedlings just like their parents. Others are more promiscuous and cross more readily with very different varieties, so you're never sure what you're going to get. Keep their seeds true by isolating plants of the same variety, using fleece or a cloche, or by hand-pollinating flowers.

More on sowing seeds:

• Your seed-sowing year
• Video: Essential kit for seed sowing
• Video: Ordering flower seed
• Video: Ordering veg seed

Identify and mark your star plants, using a ribbon around the stem or label, so that you'll know the plants to collect seeds from. Your results should improve over time, as you're continually selecting the plants that perform best in your garden's microclimate.

Sometimes it is practical to buy seed. F1 varieties are bred from known parents to reproduce useful traits like disease resistance, but the guarantee only lasts one generation and seeds from their offspring won't reliably replicate those characteristics. For best results from year to year, save from non-F1 varieties, which are open-pollinated, meaning they're cross-pollinated naturally, by insects or wind.

Your saved seeds should store well if you take time to clean and pack them carefully. Pick out as much chaff and debris as you can, and reject any damaged seeds. Store in a paper bag or envelope somewhere dry, dark and frost-free.

Here's how to collect seed from all kinds of veg plants.

Biennials

Includes:

• carrots
• leeks
• beetroot
• parsley

How to do it: these spend their first season making leaves or roots, and flowers and seeds in the second. So for these, leave your best specimens in the ground through winter for a seedy harvest the following summer. As soon as the flowers turn brown and dry, snip the whole seedhead off and tip into a paper bag. Separate the seed and chaff by rubbing gently in a wire kitchen sieve.

Brassicas

Includes:

• kale
• purple-sprouting broccoli
• calabrese
• rocket

How to do it: Only let one type of brassica flower at a time as they cross-pollinate easily, producing strange hybrid offspring. They produce huge, brilliant-yellow flowers, loved by bees, followed by slender seedpods. Once these start turning from green to straw yellow, they're ripe. They burst open easily so bring the whole seedhead indoors and rest it on a sheet to dry out. Crush the pod to extract the seeds, then remove chaff and debris by blowing gently over the top, and passing the seed through a fine sieve.

Large seedheads

Includes:

• lettuce
• coriander
• dill

How to do it: wait for the flowers to turn into brown, dry-looking seedheads, then start collecting. Cover smaller seedheads, like dill or coriander, with a paper bag just as they're ripening, so the seed doesn't fall on the ground before you have a chance to collect it. Then snip the whole head from the stalk and turn it upside down so the seeds fall into the bag, shaking it a little to loosen them. Lettuce seedheads will be too big to fit into a bag, so upend them into a clean, dry bucket instead.

Peas, beans and radishes

Includes:

• peas
• climbing beans
• broad beans
• radishes

How to do it: Let the pods develop fully on the plant until they turn a crisp, papery brown. If it's wet, cut the whole plant and hang upside down in a greenhouse or sunny conservatory to finish ripening. Pick the pods soon after they dry or they'll burst open and scatter seed by themselves. Crack open the dried case and remove the contents to store in a labelled envelope until spring.

Squash and peppers

Includes:

• squash
• pumpkins
• peppers
• chillies

How to do it: cut the fruit in half and scoop out seeds with a spoon. They'll come with lots of soft tissue attached, so rinse them clean in a colander and remove any fibres. Spread out on a piece of kitchen towel to dry for week somewhere bright but not hot. Squash and pumpkins will readily cross-polinate with each other, as will peppers and chillies, giving unpredictable and potentially sterile seeds. To make sure that next year's peppers have the same characteristics as their parents, isolate one variety with a fleece tent as they come into flower. Hand-pollinate squash flowers just as they're opening - choosing other flowers from the same plant or other plants of the same variety.

Tomatoes

How to do it: Scoop out the seeds into a jar of water. Soak for two days. Strain and rinse the jelly from the seeds. Spread seeds on kitchen paper and dry on a window sill for two weeks. Store the paper with seeds attached. Sow by laying it flat onto compost, like a seed tape.