Good timing in sowing seeds is a key to having transplants of the right size to set out in the right weather. Three important things to know are:
1. The first and last expected frost dates for your area.
2. The kind of weather liked best by the young plants of the types you’re growing.
3. The number of weeks from sowing to setting-out size.
You can ask your local county extension agent for the frost dates and other Seasonal Benchmarks for your area. You can also find this information in publications like the Farmer’s Almanac, and online by searching for “US Frost Free Dates.”
To find out when you ought to sow, first pick out the right date for setting out in your area; then count back the number of weeks to grow garden-size transplants. Sort your seed packets into groups by the date you want to germinate them.
Some seeds need warm temperatures (about 70° F) or even warmer to germinate. Others need cool temperatures (about 55° F) or freezing to germinate well. Young plants may prefer a different temperature to grow on than the seed did to germinate. Remember that the germination temperatures we talk about refer to soil temperature. Indoors, soil temperatures will approximate the average of day and night temperature for the location. Outdoors, soil temperatures will be slightly below this average in spring and slightly above it in fall.
If you are sowing seeds in a seed flat or tray, you may be wondering how many you will need. The rule of thumb is that for each 50 square inches of tray surface area, broadcast-sow:
• Up to 50 large seeds • Up to 100 small seeds • Up to 150 tiny seeds
One or two varieties may be sown in each seed tray; just make sure to label them. You should sow rather thinly in the tray, allowing enough space so seedlings won’t grow together and get overcrowded before they’re ready to transplant.
If you are using individual plugs or cells, such as a Bio Dome, just sow 1 or 2 seeds per cell.
Most seeds will germinate readily, but the trick is to keep them growing! For this, you need moisture, of course, as well as heat and light. If you have a heat mat and grow lights (wide-spectrum plant lights), all the better. But if you do not, don’t worry: room temperature in your home will probably be warm enough for most seeds, and other types of light, such as kitchen fluorescents or even a very bright window, will work for many. Your seedlings may not grow as quickly as those grown under optimal conditions, but they will still thrive. You can experiment with moving them to new locations to maximize their access to heat and light.
Transplanting the Seedlings
Your seedlings are ready when both the following conditions are met:
- The seedlings have at least 2 sets of true leaves. This does not include the very first pair of “leaves” that they grew. These are actually cotyledons, and they will shrivel up and fall off as the seedling grows.
- The weather outside meets the conditions stated on the seed packet. If one condition is that the nights should be above 55 degrees F before the seeds are transplanted, for instance, do not try to put them out before this time, even if it is past the “frost-free” date you planned for. Nature does not follow a calendar, and the frost-free times are only averages of expected dates for your area. Every year will be slightly different, and occasionally a season will be very late indeed.
When it is time to transplant, prepare the seedlings with a “hardening off” period. This simply means that over the course of a few days, you want to expose them gradually to outside conditions. The first day, you may want to put the seed flats or pots outdoors in a protected area for a few hours in the afternoon, bringing them in before the temperature drops in evening. The next day, they may stay outdoors all day. The third day, they may spend the night outdoors, still in an area protected from strong wind and lashing rain. Adjust the hardening off period to suit the needs of your seedlings and the weather conditions in your area.
Try to choose an overcast day to plant. Do the transplanting in the morning, and water the seedlings in well. If the weather has warmed up already and you are transplanting some seedlings into a full-sun location, you may want to put up a shade cloth for a few days, to help them adjust to the new conditions. Conversely, if the weather takes a sudden dip, you may want row covers or Kozy Coats to protect tender seedlings from a late frost.
Growing Up Outdoors
For the first few weeks after you transplant your young plants, keep an eye on their progress. Most plants will be happy and begin to grow vigorously, stimulated by sunshine, unlimited root space, and fresh air.
Occasionally, despite what the seed packet says, some plants will prefer more or less shade than they are getting. Others seem to need more or less water, or protection from harsh wind and rain. You will be able to tell how your plants are growing, and can make adjustments accordingly. Never hesitate to dig up a plant and move it. Better to relocate it now, before its roots take hold, than to wait and perhaps lose the plant!
Starting the garden from seed is economical and gives you many, many more options for plant varieties. But perhaps the most rewarding aspect of all is being able to watch a plant transform from a seed into a tiny seedling and finally into a strapping plant! Have fun gardening this season!