One of my favorite early outdoor garden activities is to plant seeds of cold tolerant vegetables on the south side of a fence. The reflected heat from the fence causes the soil to warm by early March. I have also used the south side of the house in another location. I increase the warmth by covering the soil with clear plastic. The radiant heat of the sun through the plastic can raise the temperature by 10 to 20 degrees. I have added a lot of organic matter such as compost and bark dust to this area so it is darker in color, loose and friable for planting seeds.
I plant transplantable vegetables such as broccoli, cauliflower, cabbage, beets, lettuce, spinach and onions. I plant short rows of each depending upon how many plants I want. I cover the area with clear plastic held in place with rocks. I lift the plastic and water often with warm water from a sprinkling can so the soil stays moist on top. Some seeds will germinate within two weeks. After four to six weeks I can remove the plastic.
All of these vegetables are tolerant of mid-April low temperatures in the high 20s. Starting in mid-April I will transplant them to the vegetable garden spacing them according to their needs. I also plant a few radishes which are ready to harvest by April.
I have also used this area to start flower seeds and root cuttings of Verbena, Diascia, Ivy and other plants which I plant in containers. I buy a few plants, take some cuttings from each, and stick them into this area covered by clear plastic. After they root I have a lot more plants for my hanging baskets and other containers.
I plant tomatoes, peppers and other heat loving vegetables in the area with reflected heat in May. They grow faster and mature sooner with the extra heat.
Don’t try starting seeds of tender vegetables outside unless you wait until warmer weather and are ready to cover with blankets or quilts to protect from frost.
I start my tomato and pepper seeds inside next to a south facing window in March. As soon as weather warms into the 50s in April, I put plants outside in the daytime and bring them back in at night. This produces much stockier plants.
Allen Wilson can be contacted at firstname.lastname@example.org