Many years ago, I was determined to harvest the first ripe tomato in the neighborhood. Old timers warned that May 17 was the critical last frost date in this area. Three killing frosts could be expected after the peepers began to fill the night with their high-pitched trills, or so went local lore.
Originally from South America, tomatoes suffer when temperatures dip below 50 degrees. Still I kept planting my seedlings earlier each spring, until a cold night in April took my entire tomato crop. Nowhere is the adage learn from ones mistakes more apt than in gardening. Luckily Mother Nature gives us another chance with the return of subsequent years.
So began my experimentations with numerous devices to protect these cold sensitive transplants from springs erratic temperatures. First, it was inverted nursery pots or gallon milk jugs with the bottoms cut off placed over the tender plants each evening. These were economical yet inelegant versions of the glass cloches used extensively in European gardens. The difficulty was remembering to remove these containers before the suns heat cooked the plants the next morning. Simple as this may sound, the routine quickly became cumbersome.
I moved onto commercially available water teepees, which were truncated, double-walled cones made of plastic tubes filled with water. Warmed by the sun during the day, the water slowly released heat at night. Unfortunately the thin plastic would spring a leak in a season or two. After many attempts at patching these holes, I eventually gave up and decided that at $4 each, I would be better off simply delaying my transplant date.
I continue to experiment with ways to extend my plants growing season. My most successful technique is planting in low tunnels made by draping 6mm plastic over semi-circular supports spanning the width of my beds. I made these hoops by bending ¾ plastic water pipes and securing the ends to the wooden sides of my raised beds.
By capturing the suns rays, these miniature greenhouses warm the soil and provide protection from harsh winds and excess water. Indeed, the air temperature in these tunnels can soar on sunny days. I simply release the heat by lifting the plastic accordingly.
The tunnels enable me to plant many different varieties of cold tolerant plants four to six weeks earlier in the spring and later throughout the fall. In February I plant peas in the tunnels friable soil when snow blankets the paths in the garden. By May the tall pea vines provide welcome shade for a variety of salad greens.
The tunnels greatest success came two years ago. Another axiom to remember in gardening is that nothing is etched in stone. We had a killing frost on May 19, 2009, two days after what was supposed to be last frost. In their miniature greenhouses, my tomatoes survived.
Transplanting tips Acclimatize seedlings by placing in a sheltered spot outdoors for an hour and increasing length of time daily for a week or two.
Transplant on a cloudy day or in late afternoon.
Water seedlings before removing from container.
Dig a hole twice as deep as the root ball. Place a spade full of well-rotted compost and finely crushed eggshells in the bottom of the hole.
Plant tomato deep, with its stem buried several inches below the first set of leaves. Being a vine, the portion in contact with the soil will develop roots.