Saving seeds is part of sustainable landscaping

Daniel Gill, Young, John, Owings, Allen D.  |  9/4/2009 6:10:14 PM

Sustainable Landscape News From LaHouse Distributed 09/04/09

By LSU AgCenter Horticulturists Dan Gill, Allen Owings and John Young

Saving seeds from plants growing in your landscape can be a part of sustainable landscaping – it saves you money from buying new seed unnecessarily.

Many summer-blooming annuals, perennials and vegetables are setting seeds now. You can harvest those seeds, store them and next year grow a new crop.

Of course, 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 one way to do it. You do need to keep a few things in mind, however.

Many 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.

Cross-pollination also can be a problem. Cross-pollination occurs when two or more different cultivars (varieties) of the same plant grow in the garden. Insects visit many flowers and can easily transfer pollen from the flowers of one plant to the flowers of another. Seeds from cross-pollination produce offspring that blend characteristics of both parents. So, always try to isolate cultivars from one another or plant only one cultivar if you are planning to save the seeds, particularly 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 and so don’t know what to look for when harvesting the seed. The best way to learn what the seeds look like is through experience (or by examining seeds you bought). You might think appearance would be obvious, but seeds come in a bewildering array of shapes, colors and sizes, and they are not always easy to distinguish.

When collecting your own seeds, make sure they are mature before you harvest them. If they are not fully mature, the embryo inside the seed will not be fully formed and cannot finish development after being 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 fruits 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. Cut open the mature fruit, remove the seeds, clean off any pulp, dry them thoroughly and store them until 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, 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 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 should be stored and planted next spring or summer. To retain maximum viability, the storage conditions must be cool and dry.

To store, first, make sure the seeds themselves are 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 it with 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 usually 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. We have found the American Horticulture Society’s “Plant Propagation,” edited by Alan Toogood and published by D. K. Press to be excellent and comprehensive.

Come to LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is located near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge across the street from the LSU baseball stadium. Go online to Louisiana Yards and Neighborhoods for additional information.

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Editor: Mark Claesgens

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