Introduction to Seed Saving, Part 1: Dry Seed Production
Dry seeded crops are quite easy to grow, clean, and save. On High Mowing Organic Seed’s Production Farm, we produce multiple species and varieties of dry seeded crops each year. As always, we are happy to disseminate all information about our seed growing and saving techniques. To positively impact your community and local food supply, we encourage you to engage in saving, producing, and breeding vegetable seed. What are “Dry Seeded” Crops? Dry seeded crops are those plants with seeds that are usually housed in a pod, capsule, or seed head. Dry seeded crops are a great introduction to saving seed. The crops are mostly easy to grow and are easy to process and clean. At High Mowing, we produce seed at various scales the following dry seed crops: onions, corn, beans, but mostly what we focus on is Brassicas (mustard greens, broccoli). HMS Seed Production Farm: Producing Ruby Streaks Seed To better understand what it means to grow and harvest a dry seeded crop, we’ll follow Ruby Streaks mustard, a popular variety of mustard green, from seeding to processing: Seed to Seed We start our dry seeded crops in the greenhouse in early April. Ruby Streaks is seeded into 72-cell trays and started in the greenhouse for around three weeks. Once outside temperatures have begun to hover around 27°F at night we move them outside to harden them off and to induce vernalization (read our related blog post about vernalization). Plants harden off/vernalize for a week or more and then are transplanted into the field at 18-24” between rows and 4-6” spacing within the row. The Process of Roguing Before crops flower and begin to set seed, we rogue (remove plants that do not exhibit the characteristics we want within the plant population). Roguing keeps a variety pure. In a population of thousands of plants there can be some genetic variability, even within very stable open-pollinated varieties. To maintain a pure line, we cull plants that exhibit variations from the desirable traits. Ruby Streaks plants must exhibit a strong purple color at a young age and have a jagged leaf. With Ruby Streaks, the first round of roguing occurs while the plants are still in the greenhouse, a second time when we transplant, and then lastly before they begin to flower, always looking to remove any plants that do not possess expected characteristics. We want undesirable genetics removed from the plant population before pollination starts! True Isolation Plots Crop isolation is critical in seed production to maintain pure seed crops. Some crops, such as corn, cross-pollinate easily, and need a distance of up to a mile and half to maintain pure strains. Other dry seeded crops like beans and lettuces don’t cross pollinate readily, and don’t require large isolation distances. We keep Ruby Streaks isolated by a half mile from other Brassica juncea crops such as Golden Frill mustard, which we also grow for seed here. Another important thing we keep in mind is that some wild plants can cross with cultivated plants, for example, Queen Anne’s lace, will easily cross with any cultivated carrot variety as they both belong to the species Daucus carota. Raphanus raphanistrum (wild radish) grows along edges in our production fields—and throughout New England—and will cross with domesticated radish seed crops. A population of wild relatives within crossing distance can ruin a seed crop. Seed Maturity After the Ruby Streaks crop has flowered and had thorough pollination, plants will begin to set seed pods. Immature seed pods are green but as the plant ages, the seed pods will begin to dry down and turn brown. We check for maturity by pulling off some of the pods and rubbing them between our hands. If the pods easily split and the nice hard round seeds can’t be ground between our fingers, the seed is mature and ready to harvest. It is important to allow at least three no rain, sunny days before harvest, if at all possible. Seed Harvest and Processing For basic dry seed harvesting we use the following tools:
- A sharp pair of pruners (I like the Felco #7 or # 13)
- A sharpener for the pruners
- A clean tarp with no holes. Tarp size depends on the amount of plants you are processing for seed.
- A 4x4 pickup truck, or a grain flail (easily made on farm)
- A black vegetable crate.
- A box fan
- 3 large totes
- Ashworth, Suzanne. Seed to Seed: Seed Saving and Growing Techniques for Vegetable Gardeners.
- Deppe, Carol. Breed You Own Vegetable Varieties: The Gardener's & Farmer's Guide to Plant Breeding & Seed Saving
- McCormack, Jeffery H. Seed Processing and Storage: Principles and practices of seed harvesting, processing and storage: an organic seed production manual for seed growers in the Mid-Atlantic and Southern U.S. Available as a PDF online.
- Navazio, John. The Organic Seed Grower: A Farmer’s Guide to Vegetable Seed Production.