It’s also very satisfying, relying on your own skills and watching your garden develop with plants that have been grown from seed you collected during the previous season.
How To Collect Seed
Collecting seed is quite easy. Wait until they are ready to drop from the plant. Then, on a dry day, arm yourself with a paper bag. Either pick the pods from the plant, cut off the seed head or shake the seed directly into the bag.
Native plant seeds can be sown immediately in seed compost with added grit. These include Angelica, Foxglove, Sweet Cicely and Yarrow. Use a 3in pot or a seed tray and cover in a protective layer of grit before leaving outside in a sheltered position. Water sparingly if the compost dries out.
Cold and inclement winter conditions will then break down the protective seed covering and promote germination. If you want to appear knowledgeable, this is called 'stratification'.
To break the seeds' dormancy you can also place them in your refrigerator for a month and then sow them. The resultant seedlings can then be potted on singly and planted out when they are large enough.
Storing The Seed
Many seeds don't require frost to germinate and will need to be stored until the spring. These include Cosmos, Lovage, Marigolds and Sunflowers.
After collection, you can sift the seed heads to remove the chaff. If the seeds are in pods, wait for them to dry and then extract the seeds. Store the seed in a cool and dark place using paper bags or food containers with a sachet of silica gel.
Start the seeds off in a greenhouse during the early spring or in a propagator when they will appreciate a little water in the morning. Pot on when the seedlings develop proper leaves.
Note that seeds from hybrid (F1) plants may not be worth collecting, they will either not be viable or will not have the same properties as the specially bred parent plant.
Of course, collecting and sowing seed will mean that you will continually have the same plants in your garden, so it's always worthwhile to augment them with a few others each year.