The middle of winter is a great time to read seed catalogs and dream about spring. There is a wealth of plant varieties available from seeds compared with the limited varieties of plants sold at the garden center. Starting seeds indoors before the growing season begins is fun and rewarding. Plants get a head start and longer growing season. Starting plants from seeds is a huge money-saver!
Annual plants (plants that live only one season) are the easiest to start from seed. Read the seed packets when choosing which plants to start. They will tell you if starting seeds indoors is recommended, versus directly sowing in the garden. Tomatoes, peppers, broccoli, eggplant, celery and most annual flowers grow well from seed started indoors. Seeds that are usually directly sown outdoors include beans, beets, carrots, corn, peas and radishes.
It is easy to become over-enthusiastic and buy more seeds than you have room to grow and to start them too early as well. The seed packet will tell how many weeks to start seeds indoors before transplanting outdoors. For flowers and warm season vegetables, such as tomatoes, peppers and eggplant, use the last frost date of May 15, and count back the number of weeks to your starting date.
Look for soil or soilless (peat, coir, vermiculite) planting mix labeled specifically for “seed starting.” Do not use regular potting soil or garden soil as it might contain pathogens that cause “damping off.” Damping off causes stems to suddenly shrivel at the soil line. Just when you thought they were going strong, your plants fall over and die!
Start seeds in their own individual small pots, or divided six packs or eight packs. It is less disruptive to the root system when transplanting individually grown plants than breaking apart multiple plants grown in a single container. Pots can be made of plastic or organic material and must have drainage holes. Pre-used pots should be sterilized by soaking containers in one part household bleach to 10 parts water for 15 minutes. Rinse them well. Seed starting kits are also available. They contain new clean pots and sterile growing medium. Fill the containers with the seed starting mix and water prior to planting. The soil will settle when watered and you may need to add more soil to bring the surface to about 1/4” below the pot rim.
Plant one or two seeds per pot at the depth recommended on the seed packet. Covering the pots with plastic will help maintain even moisture needed for germination. Be sure to label plant varieties with craft sticks or plant markers. If multiple plants germinate in a pot, cut off all but the strongest one. Pulling out plants may damage the plant you want to save.
Most seeds like warm soil to germinate. Many of our Camden homes are heated with hot water radiators. They make an ideal spot to warm your planted seeds until they germinate. Heat mats for seed starting are available at garden centers and big box stores.
Light is critical to healthy plants. Seedlings placed near a window usually do not get enough light. Window light can be supplemented with a grow light. Healthy seedlings can be grown in a dark basement using 4’ fluorescent shop lights hung by chains so the height can be adjusted as the plants grow. The bulbs should be only 2”-4” inches above the tops of the seedlings. Plug them into a household timer and have the lights on for 12-16 hours. Plants do require a dark period each day, so do not leave the lights on all the time.
Watering seedlings is a delicate matter. A stream of water from a watering can might dislodge plants from the growing medium. Water the soil with a spray bottle or place the pots in a tray of water and let them soak up water from the bottom. Do not leave the pots sitting in water for more than 15 minutes. Keep your seedlings damp, not soggy.
When the seedlings have grown two sets of true leaves, fertilize once a week with a general-purpose water-soluble fertilizer diluted to 1/4 of the strength recommended on the label.
One or two weeks before for transplanting seedlings outdoors, begin hardening them off. “Hardening off” means placing the plants, still in pots, outdoors in a sheltered area each day for a few hours. Direct sun or high winds may dry out and damage plants. Bring the plants in overnight. Gradually increase the outdoor time and amount of sun exposure each day. Transplant on a calm, cloudy day. Tear rims off peat pots so they don’t extend beyond the soil surface. When planting your seedlings, they should be planted so the surrounding soil surface is at the same level as the seedlings. One exception is tomatoes, which are planted deeper so new roots will grow along the buried stem.