Pre-Sprouting
Learned about this technique from an article by Pam Dawling as a solution to germinate seeds that require cool soil, and the need to get them started in the hot, deep-south, Alabama soil. Her web site is here.
- Crops that germinate best at soil temperatures below 80°F (27°C) include:
- beets
- carrots
- lettuce
- onions
- parsley
- peas
- spinach
- Getting good soil contact is important, so tamp the row well after planting.
- Seeds that need little soil cover to germinate are broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, cucumbers, eggplants, kale, kohlrabi, leeks, melons, peppers, squashes, and tomatoes. These seeds can germinate in light if surrounded by moist soil or they can be lightly covered with soil. From here.
- Small seeds that have been soaked tend to clump together, so after draining off as much water as possible, mix them with a dry material like uncooked corn grits, oatmeal or bran, or use coffee grounds or sand.
- To pre-sprout seeds for extended-season growing:
- First, soak them. Then drain off the water which has not been absorbed, and put the seeds in a suitably cool place.
- Rinse twice a day, draining off the water.
- Usually, it’s best to sprout the seed just until you see it has germinated. Seeds with long sprouts are hard to plant without snapping off the shoot. For most crops, 0.2 inch (5 mm) is enough. For lettuce half that length is good, and one day may be time enough.
- Spinach from here.
- 1oz (28 g) of seed per 90ft (27.4 m) row. We use a cup measure or a tablespoon that we keep in the spinach seed bucket. 7T = ½ cup. 1T=15 ml. It’s very roughly ½ cup per row.
- In the morning we drain off the excess water, and set the jar in the fridge on its side. Once a day we rotate the jar to even out the moisture and therefore hopefully the rate of growth of the shoots. After about a week the seeds have grown a short white root 1/8” (3 mm) long and are ready to sow.
- Carrots – From here.
- Mix the seed with damp potting soil or seed starting mix or peat moss; spread the mix across a seed-starting tray or paper plate.
- Place the tray or plate in a clear plastic bag, seal it, and set it in the freezer for twenty-four hours but not longer. (This is called cold stratification; placing the seed in the freezer for twenty-four hours is enough for the seed to think it has gone through a winter, but not long enough to freeze and damage cells inside the seed.)
- Then place the seed and soil mix—still inside the plastic bag (use a large zip lock bag for a paper plate)—on a seed-starting heat mat or refrigerator top or another appliance top at 70° to 80°F for three days or longer—until the seed sprouts.
- Once seeds sprout, take them out of the plastic bag—soil mix, seeding starting mix, or peat moss and all—and gently set the sprouts in prepared rows and furrows ¼-inch deep then cover them lightly with potting soil.
- Onions, Green or Spring
- Pre-sprout with them in a well-lit place so the shoot will photosynthesize and you can tell which side is up or down.
- Fill the seed starting containers with MOIST homemade seed starting mix, and tamp it down with your fingers. If you don’t tamp it, the soil will settle over time, and your roots will be exposed. Top off the flat with more dirt, but this time don’t tamp it.
- Gently grasp the seed and gently insert it root-down into the ground. Sometimes it will stand, sometimes it won’t. That’s okay. If they get covered up a bit that’s okay too, they’ll emerge in a day or two.
- Onions are heavy feeders, and they will be in this space for quite a while, pulling nutrients out of the soil. Don’t space them too closely–plant 4 to every 1 square inch.
- Sprinkle a very thin layer of vermiculite on top. This will help to prevent damping off disease.
- If the root becomes exposed gently bury that portion. If you have any that grew in upside down or crooked, then replant them.
- Beets
- Pre-sprout at room temperature.
- Plant when the little red root first shows.
- From Pam Dawling – Beets are notorious for spotty germination — their seed coats contain a germination inhibitor. Presoaking beet seed for two hours can help dissolve this compound. Room temperature water is better than cold water, and running water is the best, I’ve heard. I suspect when I’ve had failures with soaked beet seed it’s because I soaked them for too long and they suffocated due to a shortage of oxygen. Another option is to pre-sprout them just until small red shoots are seen.
- Lettuce
- Requires light to germinate.
- BUT, if nights are cool then the plant can tolerate 80° to 85° days. Per Sustainable Market Farming, pg 247.
- Historically, such days begin here in mid-October.
Soaking
- Brocolli – soak them in warm water overnight
- Cilantro – 8-24 hours
- Swiss chard – overnight per HarvestToTable.
