How to collect your own seeds

Collecting seeds from flower heads
Image: shutterstock

Although most gardeners grow plants from seed for convenience, cost or just for the sheer joy of it, not many collect and save their own seed. By collecting your seed, particularly the rarer or unusual forms, you can swap with friends or keep it as a back-up in case your plants die. Here, horticulturist Richard Bird shares his best seed collecting techniques.

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Equipment for collecting your own seeds

Collecting seed is not a difficult procedure (except in the case of some of the thistles where it is more painful than difficult!) and has the inestimable value of making the gardener look closely at his plants after they have flowered. It's surprising how much beauty can be missed by ignoring plants after their blooms have faded. Not only the function, but the shape and colour of the dispersal mechanisms are fascinating.

The equipment needed is minimal; something in which to collect the seed and some simple kitchen aids to help free the seeds from dross and debris. Paper bags and envelopes are the simplest of containers for collecting and storing. Polythene bags should be avoided unless they are used as a temporary convenience or unless the seed has been perfectly dried. Damp seed in a sealed plastic bag will soon rot. Check that the bags and particularly the envelopes have no holes in the corners. Cheaper envelopes have often been crudely folded leaving large gaps through which precious seed can trickle. Origami experts can quickly make a folded envelope from a sheet of paper which is perfectly adequate as long as the recipient is aware of how it should be opened; attacking the wrong fold first can end in disaster.

How to know when to collect seeds

This beautiful hellebore drops seeds from below
Image: Hellebore 'Hello Ruby' from T&M (© Hoogeveen/Visions BV, Netherlands)

Probably the most difficult aspect of collecting seed is in getting the timing right. Most seed, when ripe, changes colour; usually it gets darker. This change is a good indication of when to collect. Another indicator is when the pods begin to split. Here the collector must be quick because although some, like tulips and fritillaries, hold their seed in upright chalices giving the collector plenty of time, others, like hellebores, split from the bottom and the whole lot can be lost before the collector is aware of what is happening.

Not all seed changes colour, for example many of the buttercups remain green. With this family, indication of when to collect can be found by rubbing the fingers over the seed head and, as soon as it comes away freely, it's time to gather it. Similarly the fluffy heads of composites come away easily when they're ripe. The critical time to collect, just before the seed is shed, will soon be learnt (as most things in gardening are) by experience.

The most difficult are those with explosive mechanisms such as the hardy geraniums, but even these can be collected safely if the right moment is chosen, just as the capsules are almost changed from green to brown.

Fortunately not all the seed heads ripen at once on the majority of plants, giving repeated opportunities to collect the seed. Don't be fooled into thinking that by seeing flowers on the plant there will be no seed, because many plants, particularly herbaceous ones, bear seed and flowers at the same time.

If the opportunity exists, the plants should be checked each day for ripe seed, particularly those with the more dramatic means of disposal. It must be borne in mind that there may be some considerable delay between the plant flowering and the seed being produced. Cyclamen hederifolium, for example, flowers in the autumn and produces seed the following summer. No one is likely to complain about the appearance of the cyclamen during this period but, with some plants, their scruffy appearance might make the owner prefer to clear away the plant than await its seed.

What is the easiest way to collect seed?

You might need tweezers to remove the seeds from alpines
Image: Nurserymans Choice Alpine Mix from T&M

It can be a pleasant task to wander round the garden each day with a basket of paper bags collecting seed. The simplest way of collecting the seed is to pick off the complete head and pop it into a bag. Another way is to stroke off the seed with the bag held underneath to catch it.

I've found that the easiest way is to use a plastic container or bottle from which I have removed part of one side leaving the neck and bottom intact. The container is held under the seed head and the seeds shaken or stroked with the fingers so that they fall into it. With your fingers remove the bigger bits of debris. The smaller pieces can be removed by gently blowing into the container, the lighter chaff will blow out leaving the seed behind. The seed can then be poured directly into a packet or envelope using the neck of the container as a funnel. With practice this becomes a very simple method of dealing with seed and often this preliminary cleaning on site is all that is required before the seed is packeted. The bags should be clearly labelled as they are used, either by writing on the side or dropping labels in with the seed. This is absolutely vital, as it's all too easy to forget which seed is which.

Seed from smaller plants, such as alpines, can be collected in a similar manner using smaller containers or egg cups, but it's likely that the only method available will be to patiently remove the seed one by one with a pair of tweezers and certainly if the seed has been shed, then this is the only method of retrieval.

What should you do with seed once you've collected it?

Once the seed has been collected it should be left in the bags or envelopes with the top left open so that the seed can dry off, or in some cases to finish ripening. If the whole heads of plants with explosive mechanisms have been collected, it's best to lightly turn over the tops of the bags to prevent the seed being scattered everywhere. The packets should be left in a cool airy position out of direct sunlight.

When the seed is dry it can be separated from seed pods if it is still in them, cleaned, packeted and stored for future use. Cleaning is an easy, if tedious task. I once had to help clean a lot of seed brought back from an expedition, and I've never forgotten the hours spent at the kitchen table.

The idea is to remove all the debris leaving just the pure seed. Cover the work-surface with newspaper. This not only catches any flying debris and keeps the floor clean, but more importantly, it catches any seed that tries to escape. A dish with gentle sloping sides or a cut down plastic container as described earlier are ideal as utensils. Tip the contents of the packet into the dish and remove the large parts of the plant that may have been collected with the seed. Check that all the seed has fallen out of the pods or capsules. With large seed, it's then an easy matter of removing them with the fingers, teaspoon or tweezers and popping them into a labelled envelope. With smaller seed, a series of kitchen sieves can be employed, in the first instance to retain the coarser chaff and debris, allowing the seed and finer dross to pass through, and then with a finer sieve to retain the seed and allow the finer dust and particles to pass through. Any remaining waste can then be winnowed off by gently blowing over the dish. The chaff will blow out and the heavier seed remain. This all becomes very clear with a bit of practice.

How to clean fleshy seeds for storage

With fleshy seeds the procedure is a little different as the flesh must be removed before storage. With edible fruits this should produce no problems as long as you don't swallow the pip! However the majority call for more conventional methods. The flesh of these can be stripped by hand or by adding with water to a blender, and removing the soft parts mechanically (use a slow speed, or adjusted blades for this). The resulting pulp can then be washed and filtered from the seed. It should be thoroughly air-dried before storing.

How to store your dry seeds

Foil pouches can help to keep unused seed for longer
Image: Seed Storage Foil Pouches from T&M

When the seed is completely dry it can be stored in sealed paper or polythene envelopes. For short term storage it can be kept in a cool dry place out of direct sunlight. If you're thinking of keeping it for months, then the packets can be stored in an ordinary domestic refrigerator. Don't put them in the ice box or in a freezer. Refrigerators, as well as keeping the seed viable should prevent the ingress of insect pests. Storage in the open, particularly in warmer climates, may necessitate treatment with insecticides that have been specially developed for seed storage to prevent infestation.

One thing that must be stressed throughout all the procedures of collecting and storing seed is to be certain that it is correctly labelled at all times. It is so tempting to think that you will remember the name and do it later. This usually proves fatal and you end up with packets of seed to which you can give no identity.

Replanting collected seeds

Not all aquilegias will come true in open-pollinated gardens
Image: Aquilegia vulgaris var. stellata 'Black Barlow' from T&M

Another thing to remember is that, in a garden in which all the plants are open-pollinated by bees, not all seed will come true. This means that the offspring will not necessarily resemble the parent. Most species, if grown away from other members of the same genus will usually come true. Even here, there could well be different colour forms, but you would be correct in giving the same specific name. Where there are others of the same genus, wandering bees may have cross-pollinated them forming a hybrid. Some plants are more promiscuous than others. If you're collecting seed, of say, aquilegias or dianthus and have other plants around, then the packet should state that they were open-pollinated just to warn the grower that they might not be true.

Most seed from cultivars is also unlikely to come true. This is not only true of border flowers, but also fruit. Pips from a particular type of apple are extremely unlikely to produce a similar apple tree. There's no reason not to collect seed from cultivars; it's likely that you may produce another form that is even better than the parent, but any seedlings raised should not bear the name of the parent.

There are many named varieties of plants in the nursery trade which no longer resemble the originally named plant because they have been propagated from seed rather than vegetatively, which is the only way to be certain of getting an identical clone. Having said that, there are some plants which get quite near the original in appearance. For example Geranium pratense 'Mrs Kendall Dark' produces near-like seedlings, while another Geranium, G. wallichianum 'Buxton's Blue', is difficult to produce other than by seed, any non-typical forms having to be rogued out after first flowering. So it doesn't matter what you collect, as long as you label accurately; in some cases the resulting plants will leave you disappointed, in others satisfied, and in just a few, elated by the unexpected.

One final thing about labelling should be mentioned. If you're collecting seed from the wild, it's useful to note where and at what height above sea level the seed was collected. The altitude is useful when considering the plant's hardiness.

Each garden produces a rich harvest of seed. Although you may not need it yourself, try collecting some, particularly from the rarer plants in your garden. It will increase your knowledge and pleasure of plants and will give somebody else the enjoyment of raising something new, at the same time ensuring the plant's survival.

Looking for more help? Read our article on how to sow seeds successfully for tips, and see our guides on what to sow and grow each month to create a schedule. Our full range of sowing and growing equipment has everything you need to start your own plants from seed.

About the author:

Richard Bird is a former Editor of Growing from Seed and The Hardy Plant as well as two magazines on alpines.

Source of article

Growing From Seed - Autumn 1988 Vol. 2 Number 4
© The Seed Raising Journal from Thompson & Morgan