Harvesting Your Herb Seeds

by Judy Dunning

There are many different ways to start new plants such as cuttings, layering, dividing, grafting, or seeds. I have tried my hand at everything but grafting, with moderate success. But the method that is the most fun for me is harvesting the seeds in my garden to sow in next year's garden or to share or trade with friends. It seems wasteful not to do this, especially for the more unusual plants.
Harvest seed from plants that are healthy. Also keep in mind that some plants must be propagated from cuttings because either the plants do not form seeds or the seeds do not come true to variety. Calendula officinalis is a good example of this. If you started with plants bought from a nursery and collected the seed to sow at another time, the next crop of flowers will not be as spectacular or unusual as the originals.
My method of seed harvesting is really quite simple. As the flowers begin to die and the seeds are forming, I start snipping the seedheads off and lay them out in the sun on a cloth for a few days. This gives any bugs and ants a chance to escape. Be aware that some seeds are expelled forcibly and it's best to get these seedheads into a closed paper bag quickly to prevent losing them. You can hear the seedheads popping open inside the bag as they dry. I don't worry too much about the chaff unless of course, the seeds are for culinary use. When the time comes to sow the seed I just throw the chaff out with it. It will decompose within a few days anyway. It's just too time consuming to get every little piece of stem or leaf out. You can sift out the larger pieces of chaff or some people winnow it out. My efforts at the art of winnowing have not been successful. Then I gather up my seeds and put them in a paper bag to finish drying. I mark the bag with the date and name and set it aside in a warm, dry, location with good air circulation. The air temperature should be between 85 degrees to 100 degrees F. This drying process can take as long as several weeks. The reason for dating is because the older the seeds get the less viable they may become. I put a few holes in the top half of the bag for air circulation. This is especially important as your seeds are not completely dry yet. It's also helpful to shake up the bags every so often to evenly dry all the seeds at the same time. When they are completely dry and you have removed as much chaff as you can, place them in airtight containers for storage. Be sure to label your containers with plant name and date harvested. Here's a little tip; also put on the label the season/month you intend to sow the seeds. I like to sort my seeds into packages for each season, this helps later on to find particular seeds quickly. A good place to store your harvested seed is in the refrigerator assuming you have room. This will help to extend the viability of the seeds and also provide a dormancy period for those that require it.
You'll want assurance before planting as to viability of any seeds you have harvested or even those you may have received from friends. A good way to to check is take a sample and put them on several layers of moistened paper towels. Roll up the towels, place inside a plastic bag and set in a warm spot (70 to 80 degrees F). Be sure to label. Check your seeds every few days for at least two weeks to see if they have germinated. If you know that those particular seeds need light to germinate than leave the paper towels unrolled. It helps if you know ahead whether your seeds need light or dark to germinate. Other factors to consider are some seeds may need a certain temperature or need some type of pretreatment to germinate. So unless you already know this information your testing will be somewhat hit or miss. At the end of this article I will list some publications to help you with this problem.
It's important to track what you have done so be sure to note the following information in your garden journal:

The date of seed harvest
Where you stored your dried seed (refrigerator, same place you dried the seed, etc.)
Results of your viability testing
Any pretreatment you did to the seed before sowing (soaking in water, scarification, stratification)
What time of year you sowed the harvested seed
Location of newly sown seed
How you sowed the seed (scatter in garden, plant in pots, etc.)
If the seed doesn't germinate, this kind of history will help you to determine what went wrong.

When it comes to determining if your seeds need pretreatment think about what happens to them in nature. For instance, Pine cones drop to the ground, if you are standing near them when the heat of summer exceeds 85-90 degrees F you'll hear popping noises, after the winter rains you see little seedlings. The pretreatment that occurred was dry heat. Another example is Borage and Calendulas; flowers bloom, seeds form and drop, within weeks you see new seedlings. As long as there is enough water and light the seeds germinate right away. Think about the seeds the nurseries tell you to sow in the fall and yet they don't germinate until late winter/early spring. Those seeds needed some chill time and then the winter rains.
SCARIFICATION must be done if the seed coats are very hard. The process is nicking or cracking the seed coat with a knife, file or sandpaper. Be careful not to injure the embryo inside. With small seeds this process can sometimes be accomplished by SOAKING in hot water. The temperature should be between 180-200 degrees F. Afterwards let them cool and then soak for a day in cool water. Seeds treated with either of these methods must be planted immediately. STRATIFICATION is the pretreatment required if your seeds need a chilling period. Soak in warm water for a day then sow them in 6-pak containers in a moist planting mix. Put the whole container in a plastic bag and place in the refrigerator or freezer for 3 to 5 weeks.
Annual and Biennial seeds are the easiest for beginners but the lists below will also give you some perennials to experiment with.

Biennials : Clary Sage (Salvia sclarea) Mullein (Verbascum thapsus)
Parsley (Petroselinum crispum) Angelica (Angelica archangelica)

Annuals: Sweet Fennel (Foeniculum vulgare) Dill (Anethum graveolens)
Chamomile (Matricaria recutita) Chervil (Anthriscus cerefolium)
Summer Savory (Satureja hortensis) Calendula (Calendula officinalis)
Basil (Ocimum basilicum) Borage (Borago officinalis)
Sunflower (Helianthus annuus) Nasturtium (Tropaeolum majus)
Coriander (Coriandrum sativum) Marjoram (Origanum majorana)
Pansy (Viola tricolor) Sweet William (Dianthus barbatus)

Perennials: Sorrel (Rumex acetosa) Strawberry (Fragaria spp)
Burnet (Poterium sanguisorba) Catnip (Nepeta cataria)
Chives (Allium schoenoprasum) Lemon Balm (Melissa officinalis)
Lovage (Levisticum officinale) Oregano (Origanum heracleoticum)
Sage (Salvia officinalis) Winter Savory (Satureja montana)
Thyme (Thymus vulgaris) Evening Primrose (Oenothera spp)

Many benefits can be gained from seed saving besides your own enjoyment. You can improve the yield of your future plants by selecting seed from only the healthiest, largest, most attractive herbs. It's expensive to buy seeds every year for plants that you harvest heavily from such as Chamomile, where you harvest the flowers for tea. You are keeping old strains of heirloom plants alive by harvesting their seeds. Also new strains of plants have been discovered by the experienced gardener who experiments with selection and deliberate crossing of certain varieties.

Here are some books you can read for more information on this subject:

Seed Propagation of Native California Plants by Dara E. Emery
Propagation Secrets for California Native Plants by Jeanine De Hart
The New Seed-Starters Handbook by Nancy Bubel

Copyright J. Dunning 1999