When the plants in your garden look so good that you know you will want more of them next year, what are you to do? It depends upon your level of patience. You could wait until spring to buy more mature plants at your local nursery, if you want to pay full price. Right now, a visit to the clearance racks of local plant sellers may reveal some bargain plants that you could nurture back to health until next year. Your existing perennials can be dug up and divided now, so that divisions can be planted in more locations around your landscape. Alternately, if you are the patient type, then you may be able to harvest the seeds of your plants and keep them until next year, and then grow them during the early spring to plant out when the soil temperature is right.
Patient gardeners, here is a list that includes key points to remember when choosing to harvest seeds for next year.
After the darker days of winter have passed, and when spring rolls around again, pull out your seeds. Start planning your garden a little early by sprouting your seeds even before your landscape starts sending up shoots.
Make sure that the seeds you are about to harvest are fully developed. If they have not reached full, plump maturity, then it is unlikely they will be viable to plant next year. Usually, this means that the seed pods or seed heads need to have dried out and turned brown while still on the plant.
Ornamental grass seed heads should be allowed to dry out while still on the plant, then the entire seed head or plume can be cut off.
Plants such as swamp rose mallow (also known as wild cotton and Hibiscus moscheutos), form rounded seed pods that split open, to reveal dark brown seeds that can be harvested.
Butterfly weed (also known as milkweed and Asclepias tuberose, a North American native) has elongated seed pods that turn brown and dry, then split lengthwise. Each of the tiny seeds has long hairs which allow them to be broadcast in the wind, like dandelion seeds. When the pods split open, the seeds can be kept.
Named after the Greek word echinos, for hedgehog, spiky echinacea seed cones are ready to be harvested when you notice the goldfinches pecking at the seed heads. The seeds are dark brown and come away from the head easily.
Daisy seeds and sunflower seeds are mature if they fall out of the head when gently prodded and brushed by your hand.
Seeds that are damp can become moldy rather quickly, therefore losing their ability to germinate. Choose a dry day to harvest your seeds. Do not try to gather seeds during the dewy early morning, or soon after a rainstorm. Leave seeds that look like they have already developed mold on the plant. If you notice that the seeds you have harvested are slightly damp but not moldy, then spread them out on a flat surface, such as a baking tray, and allow them to dry completely. Before storing your seeds, clean out any debris, such as dried leaf material, soil, stones or petals.
Light is a big factor in allowing many seeds to germinate. Since the purpose of harvesting seeds is often to keep them over winter, and then grow them the next year, the seeds should be kept in a dark place until you are ready for them to begin sprouting.
Heat will also affect the seed and send confusing messages to the seed’s receptors. Many seeds actually need cold temperatures before sprouting. So, over the winter months, permit them to hibernate, and then introduce them to heat when spring comes around. Warmth after a cold spell will usually cause the seed to begin the process of germination.
The majority of seeds can be stored in an airtight container in the refrigerator. In this way, they will not attract pests, such as rats and mice. Do not be tempted to pack too many seeds into a small space. Seeds that are packed too tightly may sweat and cause mold growth – usually a fatal blow to any hopes of germination. Some gardeners believe in placing some of their seeds into bags of soil, then placing the bag in the freezer. In this way, when spring arrives, they can simply place the seeded soil in a warm place to begin germination. Many agree that it is not a good idea to place dry seeds without soil into the freezer.
Once you have placed your mature, dry, cleaned seeds into an airtight box, jar, canister or bag, be sure to accurately label it. Since one of the best places to keep the seeds is in the refrigerator, it is important to distinguish this container from food items that may be kept on the same shelf or in the same drawer. You may even want to write on the container a warning, such as: “GARDEN SEEDS – DO NOT EAT!” Write the date and the name of the plant on the container, or on a label attached to the vessel, using a permanent marker or pen.