Plant The Fall Seedlings
While you can start seedlings for fall crops in a protected bed outdoors, we recommend starting these seedlings indoors in the same place where you started spring seedlings; probably in the basement. There your seedlings are protected from the heat of the sun which can be a major problem for the little tykes.
See the section above on starting seeds for spring crops to get information about containers, soil mixes, and lights.
Trick for better germination - The one trick that works for most seeds without any harm is to soak the seed in a solution of very dilute seaweed or kelp solution for no more than 30 minutes before planting. Dilute here means no more than 2 tablespoons of kelp solution to a quart of water.
Temperature Management for Fall Seedlings
Seedling root growth decreases when the temperature of the potting medium gets too hot. That is one reason that seedlings grown under lights in a cool basement will experience less temperature fluctuation than plants exposed to varying sunlight and heat when grown outdoors.
If you insist on raising plants outdoors in the summer, soil temperature may exceed 85F, the point when seedling growth slows. It stops at 100F. Use cheesecloth, agricultural fleece, or shade cloth to protect outdoor seedlings during the hottest part of the day. Another solution, if you don't have too many plants, is to move the seedlings into the shade in the afternoon. In any case, try to avoid having the growing medium's temperature exceed 85F.
Watering and Humidity Management
Seedlings are never happy when their roots go dry or even with their leaves are in a very dry environment. The secret is to establish an environment where the humidity level and the water levels in the potting mix remain fairly uniform and steady.
Seedlings need to be watered when the medium is almost dry. Plants suffer as much from too much water as from not enough water. Generally, if the soil mix is appropriate, and humidity is adequate, you will need to water your seedlings every 3 to 5 days. They should not be allowed to look even slightly wilted for more than a day, or you will permanently retard their growth and ultimate productivity. Let the soil dry out sufficiently so the roots are forced to grow into the soil's air spaces as they search for water.
Too much water, on the other hand, ruins the soil structure and fills up the critical air spaces. Soil that is continuously waterlogged has no air spaces to promote root growth, and root rot eventually sets in.
Water that has gone through a water softener should not be used since it contains potentially toxic amounts of sodium. To reduce the possibility of disease problems, always water the seedlings before noon so the leaves can dry before dark. Always use water that is at room temperature to avoid shocking the tender seedlings.
Seedling systems that come with a clear plastic cover will hold the humidity level up very easily. If the seedlings are growing in containers with no cover, they are going to be vulnerable to having the humidity too low, especially in homles heated by hot air systems.
One trick that takes little effort is to find a tray that can hold a layer of gravel. Used cafeteria trays are perfect and can be found in most restaurant supply stores. You pour water into the tray so it is just below the top of the gravel. Then you set your seedling containers on top of the gravel. By keeping water in the “humidity tray” you will have sufficient humidity for healthy seedlings.
Seedlings do not need any fertilizer until they get their first set of ``true'' leaves, actually the second set of leaves you'll see. Then you can begin giving them a very dilute solution of liquid fertilizer, emphasizing the word “dilute”. This is not a case where “just a little bit more can’t hurt”. When fertilizing is overdone, salts accumulate in the soil mix to a toxic concentration. It is better to give frequent small feedings than occasional large feedings to very young seedlings. For example, if you normally mix 1 tablespoon of liquid fertilizer in a gallon of water, for the first month of a seedling's life, give it a solution with only 1 teaspoon of liquid fertilizer per gallon of water. A good general feeding program consists of this very dilute liquid fertilizer every week for the first month, and then the normal strength liquid fertilizer every 2 weeks until transplant time.
It is advisable to give your seedlings a dose of dilute liquid seaweed extract (1 teaspoon to a gallon of water) once before they are transplanted. The kelp solution reduces the problems caused by transplant shock.
A plant is ready to transplant, either to the outside garden or to another larger container, when its roots have filled the container, but have not yet begun to grow around the outside of the soil ball. If the seedling is not transplanted at that time, it can be set back permanently if its roots are forced to grow under and around the rootball. Most plants reach this stage between 4 and 6 weeks of growth. However, if a seedling's container is small, transplanting may be necessary in just 2 or 3 weeks.
If you've followed all the rules, and your seedlings still seem to be spindly and lack vigor, you should try the ``brushing'' technique. Research has shown that some form of mechanically induced stress caused by lightly brushing or rubbing the seedlings for a minute or so every day will produce stockier, stronger plants more resistant to transplant shock. Smaller seedlings can be brushed with a piece of paper folded over.
Gently brush the plants so they bend over almost to horizontal, then let them spring back. As the plants get larger, simply brushing them lightly with your hand achieves the same result. Now we are not responsible for the results if while you are “brushing” your seedlings you talk to them and tell them they are beautiful. That might work, but now you’re moving into an area of plant care that needs some further study. We talk to our plants all the time, but try to do it when the neighbors can’t hear to avoid any concern that we might be crazy.