Timing: As flowers fade, seeds form either in seed heads or pods, and eventually Mother Nature spreads the seeds, either by bursting open the pod or loosening the seeds so the wind and birds can do the work. Harvest too soon, and the seeds won’t be mature. Harvest too late, and the seeds will already be gone.
Identifying Mature Seeds: Harvest seeds when they are plump, brown, dry, and easily detach from the plant. My rule of thumb: if I run my thumb over a seed head and the seeds don’t fall out, or the seeds are still green, I leave it to mature a little longer.
Pick a Good Day: Harvest seeds on a dry, sunny day. Wet seeds will mold!
Ways To Harvest: There are a couple of ways to harvest seeds. One is to use sharp, clean scissors to snip the entire blossom into a bowl or jar and separate it later. This is a great way to capture seeds that tend to scatter easily. Or you can harvest seeds right off the plant, by shaking the seed heads into a paper bag or using your fingers to separate the seeds and drop them into a container. Be sure to use separate containers for each color, variety, or type of flower, and label them immediately. Trust me – you won’t remember later, and next year you’ll wish you knew which was which!
Dry the Seeds: Next, spread the seeds in a thin layer on a flat surface for a week or two to dry out. I save old rusty baking pans for this purpose, but you can use shallow boxes, newspaper, fine screen, or whatever you have.
Separate the Seeds: After they’re good and dry, separate any seeds that are still attached to the seed head. Rub seed heads between your hands to release the seeds, or shake pods directly into a storage container. You can also run handfuls of seeds through a sieve or colander to separate out the chaff. Some people also like to clean seeds by blowing on them gently, or by pouring them back and forth with a fan running on low to blow away dust. I tend to be in a hurry, and I don’t worry too much about this step. I just get rid of as much trash as I can.
Pack the Seeds: Seeds need to be kept dry and ventilated. Brown paper bags and paper envelopes are perfect, and you can write directly on them. For large quantities of seed, I also use glass jars, but I either leave the lids loose or rubber-band a paper towel on top to let air circulate.
Store the Seeds: Store seeds in a cool, dry, dark spot. Your garage or basement is great as long as it doesn’t freeze. Indoors works, too, as long as it isn’t near a heat source. Never let the seeds get wet.
Test the Seeds: Not all of your collected seeds will be viable. Some plants are notorious for producing a mixture of viable and non-viable seeds, and it’s also a skill that takes practice. So next spring before planting, test your seeds to be sure they’re viable. Check out our article on How To Test Seeds For Germination for detailed instructions.