Itching to get started gardening but stuck indoors? Get fingers dirty in late winter with seed starting and transplanting.
The first step in growing your own seedlings is determining when to start planting. Plants that grow very quickly, like tomatoes and zinnias should be started only 4 weeks before planting outside. Many annual flowering plants take 8-10 weeks, and for most perennial plants allow 10-14 weeks from seeding to being ready to plant outside.
Seed packets contain information about when to start seeds and usually refer to the average last frost date. That date for central Missouri is around April 15th.
Important points for successful seed starting:
- Use a soil mix intended for starting seeds, which is finer in texture than potting soil and without fertilizer.
- Always use sterile materials (soil, containers, labels) and wash hands before working around young seedlings to prevent Damp-Off, a fatal fungal disease on new seedlings.
- Moisten the soil thoroughly before sowing. Water-in after sowing by using low water pressure so as to not displace seeds. Check moisture daily and keep moist but not soggy.
- Larger seeds need to be covered with a layer of soil mix so that the seed is not visible (1-2 times the seed diameter). Tiny seeds don’t need covering because when sown they fall into the pockets of the soil protecting them from drying.
- Germinating seeds do not need sunshine during this process. Once seed leaves break through the soil, seedlings then need to have as much light as possible.
- Temperatures should be between 70-75 degrees while germinating. Using a source of bottom heat is helpful (such as the top of the refrigerator or other appliance).
Transplanting Pointers:
- Seedlings are ready to be transplanted when the second set of true leaves are present.
- Plant into a general potting soil, which will be coarser than the seed starting mix and will contain a light amount of fertilizer.
- Water thoroughly at the time of planting with a liquid fertilizer. Let soil dry somewhat between waterings, but do not let seedlings wilt.
- Provide at least 8 hours of direct sunlight, or if using artificial lighting, place bulbs just a few inches above the young plants.
- Lower growing temperatures to 60-65 degrees. Growing seedlings too warm will cause leggy and weak stems.
Growing the seedlings:
- Continue to grow in a bright sunny spot.
- Keep temps cool for sturdy, stalky plants.
- Water only when dry, almost to the point of wilting.
- Fertilize weekly with a liquid fertilizer, bi-weekly if trying to grow plants faster.
Hardening off:
- At least a week before planting seedlings outside, place the plants in a dappled shade area preferably out of the wind. By being outside, plants will adjust to the higher level of light, breezes, and cooler night temperatures. This process is also known as conditioning.
- Watch plants very closely for watering, as they will dry out much faster once outside. The first day is the most critical.
- The hardening off process prepares the plants for the eventual tough growing conditions they will need to endure.
Trouble-shooting problems:
Stretching, long distance between nodes – not enough sunlight, too warm, or too moist.
Seedlings dying off at the stem – Damp-Off Disease
Uneven germination – seed covered too deeply, allowed to get too dry, old seed
Pale color in leaves – lack of fertilizer
Withered and burned leaves when planted outside – not enough time spent hardening off the seedlings.
