For Release On Or After 09/23/11

Many summer-blooming annuals, perennials and vegetables are setting seeds now, and you can harvest the seeds, store them and then grow a new crop of plants for your garden next year. This can be fun, save a little money and allow you to share seed with gardening friends. Understand, however, that just because a plant produces seeds, you are under no obligation to plant them. But if you want to grow more of a plant, collecting seeds is one way to do it. But there are a few things to keep in mind.

A large number of vegetables and some annual flowers are F₁ hybrids (this is stated on the seed package or description of the plant). When planted, these seeds produce a generation of vigorous, productive and uniform plants. Without getting too technical, suffice it to say that the offspring of F₁ hybrids do not inherit all of the desirable characteristics or uniformity of the parents. Seeds of F₁ hybrids should be purchased new each year.

There also can be problems with cross-pollination. This may occur when two or more different varieties of the same plant are growing in the garden. Insects visit many flowers and can easily transfer pollen from the flowers of one plant to the flowers of another. Seeds that resulted from cross-pollination will produce offspring that blend characteristics of both parents. So always try to isolate varieties from one another or only plant one variety if you plan to save the seeds. This is especially true if you want the resulting plants to closely resemble the plants you collect the seeds from.

Another challenge is that gardeners often don’t know what the seeds look like, so they don’t know what to look for when harvesting the seed. The only way to learn what the seeds of a particular plant look like is through experience (or buy a package of seeds of that plant). You might think that the seeds would always be obvious, but seeds come in a bewildering array of shapes, colors and sizes, and they aren’t always easy to distinguish.

When collecting your own seeds, you must make sure they are mature before you harvest them. If you harvest seeds that are not fully mature, the embryo inside the seed is not fully formed and cannot finish development detached from the plant. As a result, the seeds will not be viable and will not come up when planted. Harvesting immature seeds is a common mistake.

Fleshy fruit usually turn from green to a color – like red, yellow or black – when mature. For instance, tomatoes turn red and cucumbers turn yellow when the seeds are mature. To harvest the seed, you have to cut open the mature fruit, remove the seeds, clean off any pulp, dry them thoroughly and store them until you’re ready to plant. Seeds are easy to identify in fleshy fruit.

For plants that produce seeds in pods – such as beans, peas, balsam, okra, butterfly weed, cleome and many others – you must allow the pods to stay on the plant until they turn yellow or brown, but harvest them before they split open and release the seeds.

The most difficult plants to harvest seeds from are those that produce seed heads, such as members of the aster family (Asteraceae) like marigolds, zinnias, black-eyed Susans, coneflowers and daisies. Once again, the seed head must be mature before you cut it off to harvest the seeds. Allow the head to turn mostly brown and dry before harvest. Then, tear the head apart over a piece of paper to remove the seeds. It helps to know what they look like, but if you can’t distinguish the seeds, save everything that looks likely.

Although in a few instances you could plant harvested seeds right away, most of the seeds you harvest now and over the next several weeks will be stored and planted next spring or summer. To retain maximum viability, the storage conditions must be cool and dry.

First, make sure the seeds are very dry. Next, put the seeds in an envelope labeled with their name and the date collected. Place a tablespoon or two of a desiccant, such as silica gel (available at craft shops for drying flowers) or powdered milk, in the bottom of a sealable container. Put the envelope (or several) into the container and tightly seal the lid. To keep the seeds cool, place the container in your refrigerator. Most seeds stored this way will stay viable for a year or more.

The seeds of some plants may require special treatment before they will germinate. This is more commonly necessary for the seeds of trees and shrubs. Seeds from commonly grown annuals, perennials and vegetables generally do not need special treatment to germinate. Still, if you think you might like to pursue growing different kinds of plants from seeds, especially woody plants, a good reference is helpful. I have found the American Horticulture Society’s “Plant Propagation,” edited by Alan Toogood and published by D. K. Press, to be excellent and very comprehensive.