Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
August, 2012
Regional Report

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Almost ready for harvest, the seed heads of this Cappuccino rudbeckia are disguised by the multitude of open flowers and the many flower buds nearly ready to open. These plants produce a bumper crop of flowers all summer long.

Time to Harvest Seeds from Your Favorite Plants

Collecting and germinating seeds from your favorite annuals and perennials is fun and rewarding, and it can be educational, too. With a little time and effort you can increase your stock of favorite plants, and even have enough left over to share with friends. I like the mystery of sprouting seeds from my garden. Because seedlings can be quite variable, you never know what you might get. I've been lucky enough to have a brand new form of an old favorite grow from the seeds I've collected.

Most perennials go from fresh flowers to dry seed heads in the space of four to six weeks. Watching and waiting are part of the game, but determining exactly when the seeds are ripe for harvest can be a challenge. This is where experience can lend a helping hand. You can usually tell when seeds are ripe by taking a close look at the old flower heads. Most of the time the seed capsules will expand slightly and turn from green to tan as they mature. When the seed capsule cracks, the seeds are ripe. The trick is to harvest before the seed capsule breaks and spills its seeds on the ground. I sometimes test a seed capsule for ripeness by gently pinching it between my thumb and index finger. If it cracks, the seeds are ready for harvest.

Harvesting Seed
For me, the least challenging plants to harvest seeds from are members of the aster family. These include marigolds, zinnias, black-eyed Susan's, coneflowers, and daisies. For seeds to be viable, the seed head must be mature before it's cut from the plant. I allow the seed heads to turn mostly brown and dry before I harvest them. To make sure I won't lose seeds, I tear the head apart to release the seeds over a piece of paper. It helps to know what the seeds look like, but if you can't distinguish the seeds from the debris, just save everything. When you plant, sprinkle the material onto the soil by gently rubbing it between your thumb and forefinger. This will further detach the seeds from the debris, and you should be able to recognize the seeds as they hit the soil. This will help you determine how thickly you're sowing them.

I collect most seeds by cutting off the seed stalk and placing it upside down in a paper bag. I allow the seed stalks to air dry for about a week and then rub the seed capsules and stalks between my hands to release the seeds.

Some seeds come away from the seed heads cleanly, others can be messy to dissect. Those with attached parachutes, like most varieties of clematis, globe amaranth (gomphrena) and little bluestem grass (Schizachyrium scoparium) require painstaking work to separate seed from feathery chaff. I've discovered that it isn't necessary to remove all the debris. I plant the seeds, attachments and all, and they germinate just fine.

Some flowers, including sunflowers, coneflowers, and daisies, produce many nonviable seeds along with the good ones, so not every seed will sprout. To find the plump ones, you can sort through your collected seed or do as I do -- just sow them extra thick, knowing not all will germinate.

Storing Seed
In some cases you can plant harvested seeds right away, but most of the seeds you harvest now and over the next couple of months will need to be stored and planted next spring or summer. To retain maximum viability, store them in a cool, dry place.

I start by making sure the seeds are very dry. I then put the seeds in an envelope labeled with the plant's name and the date collected. The final step is to place the envelope into a jar with a tight fitting lid. You can place several envelopes into a jar. For added insurance, some seed savers place a tablespoon or two of silica gel (available at craft shops for drying flowers) or powdered milk in the bottom of the jar to make sure no moisture will damage the seeds. I don't bother, but if you're new to seed saving, you might want to invest in this added insurance.

Once the seeds are safely in their jars I set the jars in a cool, dark location. Most seeds stored this way will stay viable for a year, and sometimes two.

My approach to seed saving is to keep it simple. Trial and error are just part of the game. If nothing germinates, you can chalk it up to a learning experience. If all the seeds germinate, you'll have a bounty of free plants. I don't think there's anything a gardener loves more than having lots and lots of plants!

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