My first seed harvests were from vegetables that bolted and didn’t make it to market. This worked well for a bit, and then it didn’t . I learned that if you want a reliable seed harvest, the crop has to go into the ground with that goal in mind. This means planting at the right time.
When you plant a seed crop too late, you run the risk
– The crop simply won’t have time to set seed before fall showers, hard frosts and then snow compromise harvest opportunities and seed quality.
-Or the crop might return to vegetative growth as the day-length gets shorter. In mid-August, I’ve been caught with little seed when kale and some lettuces quit producing flowers, stop maturing seeds and begin to sprout new leaves.
So how early can you plant?
Very glad you asked. How early you can plant depends on how well a crop tolerates cold and frost. Here are three ways to divide annual crops:
– The hardiest crops can be seeded as soon as the ground can be worked. This includes lettuce, peas, dill, cilantro, fava beans, overwintered roots (carrots, beets, rutabaga, onions)
– Hardy crops (but a little less hardy than the hardiest) occasionally bolt after sudden spring cold snaps. It is usually safe to seed these crops by early May directly in the field. You can plant these crops a bit earlier if you use row cover for cold protection or plant hardened off transplants instead of seeds. This category is mainly filled with annual brassicas like short season broccoli and cauliflower, and leafy greens like arugula, tatsoi, and mustards.
– Frost sensitive crops need to wait till after the last frost. Waiting a week or two longer, until the soil warms up, will create better conditions for these crop to establish. But don’t plant so late the crop won’t have time to mature before fall frosts! Row cover and plastic mulches can speed up soil warming. Nightshades (tomatoes, peppers, and eggplants), Cucurbits (squash, cucumbers, and melons), and beans are the main frost sensitive crops.
Planting any seed crop in less than ideal conditions will reveal which plants and varieties can better tolerate adversity. Recurring selection under these conditions will make the crop hardier. If you walk this road, though, be prepared to lose some crop as you learn.
And of course not all crop and varieties will be successful on all sites or in all climates.
Coming soon on going to seed: getting the seed crop to harvest, and then harvesting it.