By now you have your seedlings started and they are growing successfully. With a few more tips, you will get the best from these seedlings so when you plant them outdoors you will have strong plants that will get a jump on the gardening season.
Now that the seedlings are growing inside and once the outdoor temperatures have warmed up and the sun has increased in intensity, your seedlings may dry out quickly. Remember never let your young tender seedlings dry out completely, but also do not let the soil remain soggy. On the really warm and sunny days you may have to water twice a day. If you have trouble keeping up with the watering, you can add synthetic chamois cloth, old cotton towelling, or multiple layers of newspaper in the bottom of the tray and soak bottom of the tray with water to help keep the pots from drying out. This is especially helpful if you are away from home for extended periods.
You should supplement with a good fertilizer with a high middle number, which represents phosphorus. Phosphorus is essential for producing strong roots and stems in the early growing stages. Fertilizers with a high phosphorus content are sometimes called seedling fertilizers or transplant fertilizers, whatever the name, just make sure that the middle number is the highest of the three. Also make sure that the fertilizer is a water soluble powder or granule that can be mixed with water. Always follow the directions for mixing exactly as described for seedlings, on the package.
Seedlings can grow rapidly as temperatures and the spring sun intensifies. If you are using a sunny window for light, make sure that you rotate the seedling trays regularly to ensure even light exposure. Seedlings that are exposed to too much light and heat can grow very quickly, making for very spindly and weak plants. If you have to control the light or heat intensity in a very sunny window, hang a temporary curtain of sheer fabric to filter out the heat and light or move the seedlings to a window with less heat and light intensity for all or part of the day. This should help to slow down the growth of the seedlings. If you are using florescent lights to supplement your lighting schedule, do not hang them more than thirty centimetres from the plants when they are young. Move the lights up only a five to ten centimetres at a time as the seedlings grow near the light, while you still have them indoors.
When seedlings are grown in the house or the greenhouse they are used to controlled conditions. Before being planted outdoors, they need to be toughened-up so they can withstand the rigours and unpredictability of the growing conditions outdoors, like fluctuating temperatures and reduced soil moisture. This process is called hardening- off. A few weeks before you will be ready to plant your plants out in the garden, you need to place them outdoors for a while each day. Start by placing the seedlings outdoors for a few hours each afternoon in an area in your yard that is not in the direct sunlight. Also at this time you want to reduce the watering process a bit, again never let them become really dry but if they do not need watering everyday, then hold off until the soil is dry to the touch. As time progresses, increase the time spent outdoors each day. If the weather turns windy or cold, put the seedlings out but make sure you protect them while outdoors. Just a few days before you are going to out-plant the seedlings leave them in the garage or the shed overnight and then place back outdoors for the whole day. This helps the plant to adjust to the difference in temperatures over a twenty-four hour period and the shed or garage protects the plants from frost or freezing overnight.
With the gardening season just around the corner and proper care of your seedlings, you will be enjoying the garden much more this year. There is nothing quite like the satisfaction of seeing those plants produce a wonderful harvest and the taste of fresh produce all summer long.