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Growing Plants from Seed

Late winter is a great time to get a head start on spring by setting up a suitable place in the basement to start growing plants from seed. This exercise can be most rewarding for you and your entire family. I make an effort to try unusual and interesting plants but you might want to sow seeds for the plants that have grown happily in your garden year after year. Choose the vegetables, herbs and flowers that are your favorites!

The three essentials for seed germination are heat, humidity and light. For heat, use a seed- starting heat mat with a built in thermostat that maintains the mat at 15-20 degrees above the surrounding room temperature. The ideal temperature for most seed germination in soil is between 75-80 degrees – the room temperature should not be too cold. A temperature of approximately 65 degrees is good. The second key to successful seed growth is keeping a consistent humidity level.   If the seeds become too dry, they do not germinate, and, if they are too wet, they will rot. It is possible to make a mini-greenhouse using bent coat hangers and clear plastic. This structure creates a humidity dome. Open it periodically to allow for good air flow as this will help to prevent disease. Otherwise, keep the tray covered with plastic or glass. A mister can be used – be sure to spray frequently and consistently. And lastly, use a grow light with a timer. It should be set to remain on for 14 to 16 hours a day and turned off at night. At first, seed trays are most effective when placed 6 to 8 inches below the lights. Then raise the light as the seedlings grow.

A seed starting soil mix is the preferred growing medium because it is a relatively sterile mix. Moisten the mix and then fluff it with your hands and spread it evenly over the seed sowing trays. It is important that seed not be sown too thick because seedlings are apt to crowd each other out. Place the seed in your palm and sprinkle carefully, especially for the fine seeds. Read the seed packet for instructions on the specific seed you are working with – hard coated seed can benefit from a soaking in hot water or nicking with a file to slightly open the seed coating, whereas fine seed barely needs to be covered for successful germination.

Once the seeds are sown, mist the surface with slightly warm water. Water the seed tray by placing warm water in the base of the tray (I use a cookie sheet) or use a gentle sprinkler (I buy sprinkler tops to use on plastic bottles). Make sure to label each grouping of seeds with the date, name, and source – I use wooden popsicle sticks or plastic labels. Cover the tray with plastic or glass, turn on the heat mat and place under the light. Your seedlings will appear in no time.

It is exciting to see the emergence of seedlings responding to the conditions you have created. If the young seedlings are kept too moist, they can become diseased – this is called damping off. If this should happen, it signals a need for more air circulation. Be sure the conditions are moist – not wet. Once you have two or three sets of leaves, the little plants can be either transplanted into the garden or transplanted into a small pot for further growth. There is an important period called hardening off which is necessary for most seedlings. During this period, your plants need to gradually transition from ideal conditions to a semi-protected place before being planted into your garden. A porch or deck is perfect so the plants can acclimate to the changing conditions. They need to toughen up for the real world. This transition takes approximately five days.

So have fun, try a few “new” plants, and plant extras in pots to share with friends and neighbors!

by Holly Shimizu published in the Glen Echo News, February 2016


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