Best Care for Seedlings
If you started plants from seed earlier in the year, you should have lots of seedlings to take care of by now. The first set of seed leaves are called cotyledons; at this stage the roots are not developed enough, so do not disturb the seedling. It is not until seedlings develop their first set of true leaves that they can be moved into their own pots, a process called pricking out.
When pricking out, handle delicate seedlings carefully – by their leaves ideally – rather than their fragile stems. It’s easy to snap a stem when handling. Use a dibber or a chopstick to make a hole in the pre-moistened medium, and place the seedling into it. Carefully cover over the roots and water in. The seedling is now in transplant shock, and needs to be kept out of direct sun for a few days until it recovers. In sun it will wilt immediately, and may never recover.
Keep seedlings evenly moist, and don’t let them dry out. Watering in the morning is best so seedlings don’t sit cool and wet all night. This could trigger a fungal problem called damping off, which is caused by soil-borne fungi, usually rhizoctonia, occasionally pythium and less often botrytis or phytophthora.
Seedlings put on a lot of new growth at this stage, so after three or four waterings, start to fertilize weekly with liquid fish fertilizer or liquid seaweed. Once their roots have established, periodically check that your plants have not become root bound. Then either pot each plant on into a larger pot, or harden it off to prepare it for transplanting outdoors.
- If seeds have not sprouted, they may not be viable. Check the date on the seed package. A germination rate of no less than 65% indicates acceptable viability.
- If there is no germination, the seed may require longer to germinate. Sometimes seeds take from four to six weeks to sprout. Parsley requires 21 days for germination. Check a germination guide before you give up on your pots of seeds.
- If seeds are taking a long time to germinate, the temperature may be too cold for germination. For heat lovers like peppers, eggplants, basil and tomatoes, which require temperatures around 75°F (25°C) for germination, put seed trays on top of a source of bottom heat.
- When seedlings are yellow, it’s an indicator that they are starving due to lack of nutrients in the growing medium. Apply a weekly feed of liquid fish fertilizer or liquid seaweed.
- If seedlings are spindly and leggy, there’s not enough light for them. Increase the light by moving the pots closer to a bright window or using grow lights. Rotating seedlings daily helps them straighten up, or you can try planting spindly seedlings deeper.
- If seedlings are growing very slowly, it may be due to overcrowding, or the growing medium may have insufficient nutrients to supply all the seedlings. Try to prevent overcrowding by sowing seeds less thickly. Apply a foliar feed of liquid fish fertilizer or liquid seaweed.
- If seedlings collapse at soil level, it is damping off, caused by a soil-borne fungus. Damping off is aggravated by over seeding in warm, moist conditions.
- If seedlings are being eaten, you’ve got a critter in the area. Check for slugs or sow bugs that love munching on tasty new seedlings. Check between and under the pots and trays, and find the culprit before it dines on all your plants!
Carolyn Herriot is author of The Zero Mile Diet and The Zero Mile Diet Cookbook, available at your local bookstore. She grows IncrEdibles! in Yellow Point.