Those who live in Northern climates, where nights are long and days are short during the winter, often face the difficulty of providing adequate light for young seedlings started inside in late winter. Although grow lights are an option, if you don’t have a room or simply prefer not to install grow lights before starting your seeds-there is another option.
Making the Tray
Cut a cardboard box down so the sides are about 4 to 5 inches high. Although any size box will do, small boxes allow you to set them on a windowsill or plant stand near the window.
Line the inside of the box with heavy-duty aluminum foil so that the shiny side faces outward. Add approximately 2 inches of moist seed starter.
Planting Your Seeds
Follow the planting instructions for your specific flowers or vegetables. As a rule, plant seeds to a depth of two to three times the diameter of the seed. Fine seed can be pressed into the soil with your hands and covered with a fine layer of seed starter. Some seeds, such as many wildflower seeds, require light to germinate and do not require covering with soil. Always refer to the seed packet to be sure.
Mist the soil to moisten the seeds and cover the top of the box with plastic wrap. This keeps soil moist and holds in humidity.
Place the box in a warm location to speed germination. The top of a water heater or other appliance that radiates slow, constant heat is ideal.
Check the seeds daily. If excess moisture builds up inside the box, open the edge of the plastic to allow vapor to escape and air to circulate. Punching small holes in the plastic also helps equalize moisture.
Move to Bright Indirect Light
Remove the plastic once seedlings appear and move the box to an area that receives bright indirect light. Direct sunlight can easily damage young seedlings. The aluminum foil inside the box reflects light increasing light exposure without the risks associated with direct sunlight. Because the light reflects from the foil from all sides, seedlings typically do not need to be turned to keep them growing straight.
Keep the soil moist, but not soggy, to encourage healthy growth. Because their root systems are still small, seedlings can shrivel and die within hours if the soil dries completely.
Begin a routine of fertilizing with a water-soluble fertilizer once seedlings are 3 to 4 weeks old. Mix the solution to ¼ strength and apply once a week.
Making a seed starting tray lined with aluminum foil reflects light to your seedlings and encourages healthy plant growth and makes caring for your seedlings easier. Instead of stretching for the source of light, these seedlings grow straight and eliminate the need to turn your plant trays every day.