Kat Lavers on seed saving for home gardeners


Kat Lavers, from Northcote, tells you all you need to know about seed saving. The notes were written in February 2021. Kat also made a 2 hour Zoom presentation on the subject at the same time. Finally, See Kat’s website.

Seeds are embryonic plants. They form an important part of the lifecycle of many species, and may be adapted to survive drought or other adverse conditions, to disperse on the wind or camouflage from birds on the ground. Some are designed to germinate only after rain, fire or after passing through an animal’s stomach!

There are many reasons to save your own seed. It is far cheaper and your seeds will usually be fresher and stronger than what you can buy in shops. You can also gradually develop new varieties with the flavours you love and they will become more adapted to your garden’s conditions over time. Finally, we are at risk of losing thousands of open-pollinated seed varieties because they are not commercially valuable so, by saving seeds at home, you are helping to preserve the genetic heritage passed down by our gardening ancestors.

Note that some plants are reproduced through other methods: spores (mushrooms), rhizomes and tubers (Jerusalem artichokes, potatoes), division (many perennial herbs), bulbs (garlic), grafting and cuttings (most fruit trees), etc.

Hybrid versus open-pollinated

Hybrid seeds are a cross between two genetically different varieties and are usually marked with F1 on their packaging. Hybridisation is carried out by hand (or sometimes accidentally by insects!) and is not the same as genetic modification. Hybrid seeds often display strong vigour and increased yields, but they are more expensive and seed saved from these plants will usually not produce true to type plants. Note that hybrid seeds can be stabilised in 6-12 generations to create open-pollinated seeds.

Open-pollinated seeds have more diversity in their genepool and are able to adapt over time. Their seed is stable – it can be saved and will produce true to type plants.

So if you want your vegetables to look and taste like their parents, choose open-pollinated varieties!

Understanding pollination

Pollination occurs where pollen produced by the male parts of the flower (anther) is deposited on the female part (stigma) of the flower. Normally one flower has both male and female parts, but some species have separate male and female flowers on the same plant (eg. pumpkin family) and some species have separate male and female plants (eg. asparagus).

Self-pollinating (inbreeding) plants – where pollen is moved from the male to the female parts of the flower on the same plant. In some flowers, the male and female parts are so close that only the slightest wind is needed to transfer the pollen (eg. lettuce, tomato, okra). In peas and beans, pollination occurs before the flower is even open! Some cross-pollination can occur between plants even when they are self-pollinating.

Cross-pollinating (outbreeding) plants – these plants require wind (eg. silverbeet, sweetcorn) or insects (e.g. brassicas, carrots, onions) to transfer pollen between plants.

To exclude pollen from other varieties and ensure your seed grows true to type, you can use isolation (large distances between varieties), bagging or taping up of flowers, caging plants, hand pollination and timing. Remember that pollen from wild relatives or neighbour’s gardens can be carried in by wind or insects.

Maintaining genetic diversity creates resilience within a variety, and is especially important for cross-pollinating plants that can decline in vigour unless many individuals flower together. Commercial seed distributers are advised to collect seed from a minimum of 20 inbreeding and 100 outbreeding plants but obviously this is difficult to achieve in small gardens!

Don’t let this put you off saving seeds – having the ‘right’ numbers of plants and controlling pollination are rarely practiced by home gardeners, and results are usually still very good. In fact, many of our heirloom varieties have been developed through accidental crosses in home gardens. But it is important to keep in mind if you are stewarding a rare variety.

Selecting and collecting

Keep the best and eat the rest! You might decide to save seed from plants with early ripening, late ripening, pest and disease resistance, flavour, yield, colour or other desirable traits. Whatever you choose, only save seed from your best plants to make sure you are selecting for better results over time. If any plants have undesirable characteristics, remove them or at least stop them from flowering to avoid crosspollination with other plants. When you have selected your best plants, mark them with tape, ribbons etc so they are not accidentally harvested for the kitchen. Make sure the seed is fully ripe before collection – especially for zucchinis and cucumbers where the fruit is usually picked immature for the kitchen!

Seed cleaning techniques

The plant matter that is harvested along with seeds can harbour moisture, pests and diseases that may attack stored seed, so wherever possible clean your seeds before storage. There are two broad methods:

  • Wet cleaning: used for plants with seeds contained in moist flesh. Scoop seeds into water and massage vigorously, then put in sieve and rinse under running water. Dry on a labelled plate, sieve or screen, stirring daily to prevent sticking and facilitate even drying. Some seeds in gel-like casing (eg. Tomatoes and cucumbers) benefit from fermentation to assist cleaning and reduce disease transfer. To ferment seeds, simply cut open the vegetable to expose the seeds and gel to the air, and let them sit for about a week, before proceeding with basic wet cleaning.
  • Dry cleaning: used for all other plants. Leave plant to produce dry seeds on plant as long as possible, then roll, crush, winnow or sieve to remove chaff.

Make sure that the seeds are fully dry before storage or they will rot. Leave for a few weeks somewhere warm and shaded where they can continue to dry at less than 35 degrees. Large seeds that are sufficiently dry will shatter rather than crush when hit with a hammer.

Seed saving by plant family

Fabaceae (bean family aka legumes)

E.g. beans, broad beans, peas, snow peas.

Rating: easy.

Pollination: self-pollinating (although some cross-pollination from insects can occur). Can bag blossoms with light polyester mesh to allow light without increasing temperature and humidity, but control generally not required for home gardeners.

Seed is read to harvest when pods begin to turn yellow and dry.

Cleaning method: thresh or hand pod and sieve or winnow chaff. When dry, freeze for 2 days to kill bean weevil eggs.

Seed viability: 3-6 years.

Solanaceae (tomato family aka solanums)

E.g. tomatoes, capsicums, chillis, eggplant.

Rating: easy.

Pollination: self-pollinating (although some cross-pollination from insects can occur between currant – Lycopersicon pimpinellifolium – , beefsteak and potato-leaf tomatoes with protruding styles). Wind or mechanical agitation is required for pollination. Isolation or caging can be used to control pollination, but generally not required for home gardeners.

Seed is ready to harvest when fruit is overripe and becoming soft.

Cleaning method: capsicum and chilli seeds can be scraped out and dried. For species with juicy fruit, scoop pulp out and allow fruit to ferment for 1-3 days to break up gel pulp and avoid disease transmission. Or simply squeeze pulp onto kitchen paper and dry.

Seed viability: capsicum 3 years; tomatoes 3-10 years, depending on variety; eggplant 7 years.

Note: whilst potatoes are in the solanaceae family, they are propagated vegetatively.

Amaranthaceae (beet family)

E.g. silverbeet, chard, beetroot, spinach, amaranth, quinoa.

Rating: easy.

Pollination: wind pollinated. Control pollination by bagging a number of seed stalks grown closely and tied to a stake.

Seed is ready to harvest when flower heads start to dry and a few seeds start falling. Can be stripped from the plant while in the garden and drying completed elsewhere.

Cleaning method: thresh seed and winnow or sieve to remove chaff.

Seed viability: 4-6 years.

Note: beetroot is biennial so plants will overwinter and flower in their second year.

Apiaceae (carrot family aka umbells)

E.g. carrots, parsnips, parsley, fennel, dill, cilantro/coriander, celery.

Rating: moderate.

Pollination: insect pollinated, use isolation or bagging umbels to keep varieties pure.

Seed is ready to harvest when umbrells start to dry and a few seeds start falling.

Cleaning method: thresh seed and sieve to remove chaff.

Seed viability: carrots and parsley 3 years; dill 5 years; celery 8 years.

Note: Many root crops in the apiaceae are biennial and will overwinter and flower in their second year.

Asteraceae (lettuce or daisy family)

E.g. lettuce, endive, chicory, sunflower.

Rating: moderate.

Pollination: mostly self-pollinated but require wind or insect agitation. Control pollination to keep varieties pure with isolation, hand pollination or other methods (caging).

Seed is ready to harvest when flower heads start to dry and a few seeds start falling.

Cleaning method: thresh seed and winnow to remove chaff.

Seed viability: lettuce 3 years; endive, chicory and sunflower 7-8 years.

Note: Jerusalem and globe artichokes are in the asteraceae family but are propagated vegetatively.

Amaryllidaceae (onion family aka alliums)

E.g. onion, spring onions, leek, chives, garlic chives.

Rating: moderate.

Pollination: insect pollinated, control pollination to keep varieties pure.

Seed is ready to harvest when flower heads start to dry and a few seeds start falling.

Cleaning method: thresh seed and winnow to remove chaff.

Seed viability: 2-3 years.

Note: Garlic and perennial onion varieties are in the amaryllidaceae family but are propagated vegetatively.

Cucurbitaceae (pumpkin family aka cucurbits)

E.g. pumpkin, cucumber, zucchini, squash, watermelon.

Rating: moderate.

Pollination: insect pollinated, with male and female flowers on each vine. Members within the same species will cross-pollinate. Hand pollinate by selecting male and female flowers the night before they open and taping to prevent insect entry. In morning cut the male flower, remove petals and rub onto female flower. Tape female flower shut until it withers.

Seed will continue to increase in strength and size for 20 days after mature fruit is picked. Mature fruit for seeds is generally picked much later than fruit for cooking in this family, except in the case of pumpkins.

Cleaning method: wet clean the seeds and dry. Seed in jelly-like sacks can be fermented (especially cucumbers) which may improve germination.

Seed viability: 5-6 years.

Note: chokos are also in the cucurbitaceae family but their seed is unable to be removed from the fruit and therefore the entire fruit is planted.

Poaceae (corn family)

E.g. corn, maize.

Rating: difficult.

Pollination: wind pollinated, plant in large blocks or hand pollinate. Strongly outbreeding so requires large number of plants to maintain genetic diversity (50-200). Control pollination with isolation or hand pollination.

Seed is ready to harvest when ears of corn are completely mature, and can be dried in the field or picked for further drying.

Cleaning method: schuck the cobs when dry.

Seed viability: sweet corn 3 years; maize 5-10 years.

Brassicaceae (brassica family)

E.g. broccoli, kale, cabbage, cauliflower, Brussels sprouts, radish, mustard, kohlrabi, turnip, bok choi, pak choi, tatsoi, rocket, etc.

Rating: difficult.

Pollination: all members within a species can cross (Brassica oleracea includes broccoli, cabbage, kale, Brussels sprouts, kohlrabi, collards and cauliflower so they can all cross with each other!). Insect pollinated. Outbreeding so requires large number of individuals to maintain genetic diversity. Control pollination with caging and hand pollination or isolation, though home gardeners do okay for a few years without controls.

Seed is ready to harvest when seed pods are completely dry – they will not continue to develop if harvested earlier.

Cleaning method: complete drying in a warm, shaded position. Thresh seed and winnow or sieve.

Seed viability: 4-5 years.

Tips for storing seeds

Most vegetable seeds will remain viable for 3-5 years. Larger seeds tend to have longer lifespans than shorter seeds, and fresh seed will germinate more readily than old seed so, as a rule of thumb, if the seed is very small or old then sow more to compensate. Lifespan also depends on correct storage. Make sure your seed box is rodent and weevil proof. Re-use desiccants from commercial packaging (eg. shoe boxes) to absorb moisture – dry these out once a year. Label your seeds with the variety and year collected. The ideal location for your seed box is in darkness with a cool, stable temperature and low humidity – usually not in the greenhouse, garage or garden shed!

Sourcing seed varieties

Find your local seed savers network at www.seedsavers.net. Ask your local gardening, permaculture and transition groups and don’t forget your neighbours! There are many excellent and ethical mail order seed suppliers in Australia, including Diggers, Green Harvest, Eden Seeds, Cornucopia and The Lost Seed.

Further reading

Seed Savers Handbook – Michel and Jude Fanton.
Seed to Seed – Suzanne Ashworth.
Breed Your Own Vegetable Varieties – Carol Deppe.

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