Lynne Forbragd, Extension Master Gardener in Anoka County, December 10, 2016
As a vegetable gardener living in a Zone 4 growing climate, the winter months can be a long stretch of time without digging in the dirt. With our harsh winters it can be challenging to grow a cold season crop outdoors with cold frames and can take a lot of time and experimentation. Many vegetables can be grown indoors successfully such as specific varieties of salad mixes, tomatoes, peppers and carrots, potatoes and mushrooms as well as herbs.
For the beginner gardener, microgreens are an easy way to start a hobby of growing vegetables indoors. Microgreens are a mix of salad greens and herbs that are harvested in 10-14 days when they are small and tender. This is a great way to add nutrition and added flavor to your winter salads, sandwiches and stir fries and can save the high cost of buying them at the grocery store. Microgreen seeds can be bought as a mix in different varieties ranging from mild to spicy or you can create your own mix from leftover seeds. Varieties to plant include salad greens, mustard greens, beets, broccoli, kale, turnip, Swiss chard, carrots and herbs such as basil, parsley and cilantro.
To plant indoors, fill shallow trays that have drainage holes with 2” of potting soil. Water the soil evenly and let drain before broadcasting your seeds evenly ¼”- ½” apart. Gently press seed into the soil and cover lightly with potting soil. Keep covered with plastic until you see the first signs of growth. Soil temperature should be 75 degrees Fahrenheit to germinate, then down to 60 degrees to grow. Air temperature should be maintained at 60 degrees and typically a basement area can work very well. It is important to water from the base and keep the soil evenly moist to avoid the soil from drying out. Fertilizer should be added to the soil at the time of planting and not sprayed on after the seedlings have emerged. Good lighting is needed to grow microgreens indoors. A window sill will work if you have four hours of sunshine, but keep your microgreens away from drafty windows and heat registers; otherwise instead use growing lights.
To harvest, wait until the microgreens are ½” to 2” tall and have true leaves. You can thin the seedlings by cutting with a scissor or a sharp knife, but try not to disturb the soil and roots. Wash thoroughly but minimize handling as these are tender greens and can damage easily. Microgreens can last in the refrigerator from 5-10 days.
Unlike some salad mixes, once the seedlings are cut they will not grow back. So when all your microgreens are harvested it is time to start the growing process again. You can replant in the same soil leaving the tiny roots to decompose back into the soil.