As summer hits its stride, many of the spring crops are going over, flowering and going to seed. Now is a great time to save seeds to use for fall crops or for next spring. So before you yank out all the greens that are past their prime, consider leaving just one to finish setting seed for your future plants.
The one pictured above is mizuna, one of my favorite salad greens. It's a mild mustard green that is super easy to grow and makes really tasty salads. This is what it looks like before it sets seed:
What I love about this plant is that you can harvest the whole plant down to the base, and it will regrow several times, giving you many salads per plant. Here in Northern California it grows year round, and keeping some growing means always having something green to eat.
Before saving seed, however, it's important to know two specific things about your plants:
- Were they grown from open-pollinated or hybrid seeds?
- Do they need isolation to breed true?
Open pollinated vs hybrid seeds
Seeds saved from open-pollinated plants will produce new plants that are the same variety as their parents. For example, if you plant San Marzano tomatoes this year, save seeds from one of the tomatoes, and plant them next year, those plants will give you San Marzanos because San Marzanos are open-pollinated.
All heirloom varieties are open pollinated, though there are many open pollinated varieties that are not heirlooms. Heirloom is a loose classification, generally meaning that a variety has a long history that can be traced, whereas open-pollinated is a technical term for plants that produce seed that can be saved.
Hybrids are best explained through the example of the mule. Two different species are alike enough (the horse and the donkey) that they can mate, but their offspring is sterile (the mule). Plants are a bit more complicated, but it's the same idea. Hybrid seeds (often called F1 hybrids) are created by traditional breeding methods, simply crossing one variety with another, to produce a new one that has desirable characteristics. Sun Gold tomatoes are an example, as are Early Girls. Often seeds from hybrids are not sterile (they will produce a plant), but the plants they produce are invariably unlike their parents. It's not worth saving seeds from hybrids.
GMO (genetically modified organism) seeds are a whole different category, where desirable characteristics are implanted into seeds using genetic technology in a laboratory. Home gardeners don't have to worry about these seeds because they're primarily for commercial farms. The only exception is for home gardeners in agricultural areas where there is a risk of cross-pollination from GMO crops planted nearby.
Both open-pollinated and hybrid seeds can be grown organically. GMO's cannot.
Isolation and accidental cross breeding
Some plants are what you might call promiscuous. They cross-breed freely and hybridize all on their own. The zucchini / summer squash family is a good example. If you plant a zucchini next to a yellow crookneck squash and then save seeds from one or the other, the squashes you get next season will be wildly different. Each saved seed could produce a completely different fruit, some delicious, some not so much. Unless you're ready to either isolate the plants by distance (generally 1/2 a mile), or hand-pollinate and protect fruits from which to harvest seed, don't save seed from veggies that cross breed easily. Here is a nice list of common veggies showing which ones will cross-breed.
Other plants, like tomatoes, do not cross breed easily, and you can confidently save seed from them without much effort.
In the case of these mizuna plants I'm growing out for seed, they will cross with other members of brassica rapa, including bok choi, turnips and mustard. Because I don't have any of those going to seed right now, I can safely save the mizuna seeds.
Arugula is very much like mizuna, but is its own species, and you don't have to worry about it crossing. If you have arugula plants that have decided they're over the heat and are starting to flower, you can leave them, and collect the seed pods when they're mature.
Here's an excellent, detailed article about saving seed from all the brassicas, written by one of my favorite seed growers, Kalan from Redwood Seeds.
Anyway, back to saving seeds from mizuna and arugula. The process is very simple. Keep an eye on the flowers, and watch as they develop into seed pods over a couple weeks. When the light hits just right, you can even see the seeds forming inside the pods.
Once the pods begin to mature and turn brown, harvest the whole pod into a paper bag. As they dry, the pods can burst open, scattering the seed (especially arugula).
For your lettuces that may also be going to seed right now, the process is similar, except that instead of forming seed pods, lettuce will make fluffy seed heads that look like a dandelion as it's opening. Once the seeds come away easily into your hand, they're ready to harvest. Just snip off the seed heads and put them into a paper bag.
As with all seed-saving, store your seeds in paper bags or envelopes in a cool, dry, place. And don't forget to label them as soon as you harvest!