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Collect and store seeds

Published on March 13th 2021
A close up of a flower
As we enter into the cooler autumn days, one will gradually start noticing the fading summer blooms are slowly starting to turn into seeds. Coreopsis, moonflowers and hollyhocks all drip with seeds, while vegetables like lettuce, fennel and carrots that were left to flower gradually turn their delicate flowers to tiny brown seeds, ready to be saved now for sowing again when the time is right.
A pink flower on a plant
Collecting and storing seed from your garden is one of the best ways to preserve your favourite flowers and vegetable varieties and can also help to keep the garden budget to a minimum.
In this article, we explore when and how to collect seed, and how to prepare and store seed.
What a glorious thought it is that today’s harvested seed will become tomorrow’s flourishing garden.
A close up of a hand

Collecting seed

Be sure to select healthy plants to collect seeds from and collect seeds on a dry, sunny day. Never collect or store wet or damp seed as this will result in germination or rotting caused by fungal infection.
It really is all about timing - collect it too early and the unripe, premature seed will not germinate; collect it too late and whatever is left after the birds have enjoyed a nibble will be past its best.
A close up of a tree
Ideally, nature should take its course and seed should be left to ripen on the vine, for example, beans, peas, herbs and flowers should only be harvested once dry and mature. Maturation is often indicated by a colour change from green to brown, red or black. Be careful to collect them before seedpods open to cast their contents.
Some seed can be collected when well-developed but still immature or green, for example Calendula and Ranunculus. Other plants leave such a small window for seed-collection that they should be monitored daily in case the seedpods or -capsules open and disperse when ripe.
A close up of a plant
*Tip: Tie a brown paper bag over seedpods that disperse by exploding and shake to catch all those that are ripe and ready for release.

Seed extraction

In the case of fleshy fruit, seeds need to be extracted before storage. For instance, berries and other fleshy fruit fall to the ground when ripe, the fleshy parts are removed by birds or small animals, and the seed remains. In the same way, when collecting seed from these types of fruit, it’s important to first remove the outer fleshy part and only then place it in storage.
seed sieving
*Seed-saving tip: Tomatoes need to have the gelatinous sac removed from the seed before being able to store it. For an easy step-by-step guide on collecting and storing tomato seeds, dig into the how-to guide below.

Store and collect Tomato seeds

Seeds from many plants can be saved simply by collecting them as they dry, however, tomatoes require a bit more effort. Tomato seeds are enclosed in a gelatinous sac that contains growth inhibitors and prevents the seeds from sprouting before they’ve buried themselves in the soil. This gel residue can be a problem for stored seeds as it can house seed-and soil-borne diseases, so the best way to remove this gel covering before storage is to allow the seeds to ferment. Follow this easy step-by-step guide and start storing your favourite tomato varieties for next season’s planting.

Preparing seed for storage can be quite laborious, but it will most definitely be worth it once you behold your garden in bloom or harvest the first crop grown from those exact seeds. To prepare seed, first separate detritus, chaff and other bits from the seed. Then, spread out the seed on white paper, ensuring you don’t mix seed from different species or varieties. Having a sieve and piece of tweezers nearby should prove handy.
Pumpkin seeds

Storing seed

Some seeds can be stored longer than others and there is a multitude of factors that can influence the longevity of seeds. Seed viability can drop drastically after the second and third year or storage, but this varies from species to species.
*Tip: Some seeds are best sown immediately so be sure to check when the best time for sowing is. E.g. Hollyhocks.
Seed should always be stored in porous paper bags or envelopes. Refrain from using plastic bags for seed storage as these hold moisture. Plastic containers, such as film boxes, and glass containers also work quite well.
Seed saving
Seeds are best stored in an airy room in cool, dark conditions with minimal exposure to moisture or fluctuations in temperature.
*Tip: Add a dash of cinnamon to your seed to serve as an anti-fungal agent.
Remember to label your collected seeds with a name and date collected. Just in case, place another label inside the container or packet with the seed.
Poppy seedpods

Stumbling blocks

  • Some plants are sterile and therefore unable to produce seed.
  • Some plants, like pumpkins and squash, are monoecious, meaning they carry female and male flowers on separate plants. If you only have a male plant it will therefore not be able to produce fruit or, therefore, seed.
  • Seed production requires a lot of energy for the plant therefore some years will produce better harvests than others. Other factors like water availability, frost, and temperatures also play a role in seed production.
A close up of a hand

For an easy step-by-step guide on saving seed, dig into the how to Guide below!

Flowers for an autumn seed harvest

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