It’s July, and several early flowering bulbs and perennials have already got mature seed. We collect seed from our garden plants to use in the nursery, to propagate plants that we have few of, but also to send to various seed exchanges, like the ones in The Alpine Garden Society, Scottish Rock Garden Club, Hardy Plant Society and The Cottage Garden Society has. (You have to be a member to participate in the seed exchanges, but all the societies has other great benefits of joining too, so please have a look.)
Collecting seed is easy, but you do need to be at the right place at the right time, or keep an eye on your plants so that you know when the seeds are ready for harvesting.
A plant will generally tell you when its seed are ripe. Either the seed pod or seed changes colour, the seed pod might open or the seed starts to loosen from the flower stalk. It is always best to let the seed ripen fully on the plant. Do not fall for the temptation of harvesting the seed capsules too early and hoping that it will ripen as soon as it is dried. (Sometimes you might be lucky, or the seed was nearly ripe and therefore just needed to dry a bit before changing colour, but it is always best to leave the seed pods until they are fully ripen.)
There are so many different seed and seed capsules, and they have different ways of letting you know that seeds are ripe. Some seed pods will open and the brown or black seed will fall out. Other seed are not contained in a seed capsule but will be fastened directly to the flower stalk. Observe your plant and find out what the seed look like and what it looks like when it’s ripe. This will make harvesting so much easier. Some seeds are “catapulted” away from the plant when it’s fully ripe, like those of different Geranium species, others have fluffy “tails” that lets the seed get caught on the breeze and drift away from the parent plant. Both the catapulting and drifting seeds can be difficult to harvest a t the right time, because if you’re to late the seeds have either gone with the wind or been flung into the far corner of your flower bed. A small bag made of cloth (We use a bouquet garni bag.) fastened carefully over the ripening seeds, will keep them from escaping.
We like to collect seed in a paper bag. Do not use plastic bags as seed and seed capsules harvested from the garden are usually moist, even though you might think they are completely dry.) and if kept in an air tight plastic bag there is always a possibility of the seeds rotting. We use old paper bags or old envelopes. In these paper bags the seed capsules can be left to dry properly and the seeds will generally fall out and be collected in the bottom.
We go round the garden, paper bags in one hand, secateurs in the other and collect whatever is ripe. Always remember to label the bags at once. You may think you remember what you collected and that there is no problem to identify the dry capsules, but for me anyways, that is not always the case.
When the seed is fully dried we remove the seeds and make sure to get rid of any plant debris. I only want to save seed and not bits of crushed seed capsule. After this the seed go in smaller seed envelopes either bought or ones that we fold ourself. You might get very excited and like to collect every seed on a plant but remember that a little seed can go a long way and sometimes it’s not necessary to sow 2000 seed of a plant that you only need a few plants of.
After the seed is cleaned and packed in envelopes store them at a dry, cool place. Fluctuating temperatures is best to be avoided, so a room with a constant temperature is the best.
Happy seed collecting!