Season Extenders

With 18 inches of snow still tumbling from the skies and sliding off the barn roof in mid-May this year, it’s been my grumble that we sure ought to have earned a late autumn. We had a nip of frost during that cold and drizzly week in July, but usually the fall freeziness starts up in late August on our farm—which has the pleasure of being nestled in the county’s cold spot.

Fortunately, September has been impressively mild, with the eggplants and peppers still hanging in there. Covering again to make it through our fifth frost, the dreaded hard freeze still appears a little ways off into October—added time for winter squashes to ripen. This year, we’ll take every extra day for keeping the garden growing that Nature is willing to grant us.

The Northwoods is notorious for its short growing season. Grandma always used to say that there was no sense planting much in the garden until Memorial Weekend, well after her family used to have the planting finished on the old family farms in Central Illinois. And you can be pretty sure, around here, that the ground will be freezing by later October, if not sooner. Garden into November or harvest Broccoli for Christmas dinner in these parts? Forget it!

This leaves hearty Northwoods gardeners always on the hunt for creative season extenders. Our adventures began with cold frames made from insulative bales of hay stacked to form the outline of a square. The earth below was turned, amended with compost, and sprinkled with lettuce and spinach seeds. The land sloped gently to the south, facing the low-sky autumn sun. On top was laid an old glass window in a wooden frame. This was supposed to catch and keep the warmth of the sun, helping the soil stay above freezing and warm enough for the eager plants to grow. But the buildup of moisture became a problem, and when that moisture with the added weight of snow load built up on the window pane and froze, the glass broke…and no-one really wants to eat lettuce with bits of glass in it.

So we upgraded to a polycarbonate (corrugated plastic) cold frame from Germany with hinged doors for vents that could rest on the soil sheltered along the south side of the house. Now we were able to enjoy greens as early as April, and a second late planting of provided salads weeks after the rest of the garden had froze out. But, while the small size was fine for one family, it didn’t offer us the ability to extend the growing season for our CSA members and clients.

We next tried low-tunnels, which are a method where metal hoops stuck into the ground over the bed of growing plants support a lightweight, breathable fabric. This system can be used to organically keep plants protected from pests, especially in their early and tender growing phases, as well as insulate against cold temperatures. But a low tunnel just wasn’t enough to keep the plants safe when the nighttime temperatures dipped into the 20’s.

It was time for more drastic measures! High tunnels. Also hoop-like in structure, these season extenders are supported by steel ribs high enough to walk through, encased in plastic film. Doors on the ends or adjustable roll-up sides offer abilities to control temperature and humidity, as well as air flow. Close it up through the winter and the ground might never freeze solid inside, making it much warmer in the spring to get plants started. Open it wide in the summer to allow insect and wind pollination as well as keep the moisture down. Close it back up on the chilly fall nights to keep the plants safe and growing well into October or even November. It doesn’t break (like glass) or blow away (like low tunnels), and it can withstand winter snows.

Upon entering the world of high tunnels, we opted to start small to give it a try by ordering a 12 by 24-foot high tunnel kit from FarmTek. It was our first time working with their systems, amidst the intricacies of run-away Tek screws, cantankerous saddle clamps, and ground augers that had to be dug into the rocky soil rather than twisted. But after several brave and rigorous months, we had our first high tunnel. Oh the joy of ratcheting down the top cover and hanging the door as the finishing touch. A roll-up back flap made it easy to bring in wheel barrel loads of compost or mulch, and in-ground soaker hose irrigation provided necessary water.

In the spring, we hauled out our trays upon trays of seedlings to the high tunnel for hardening off, nestled our cold-sensitive tomatoes, peppers, and eggplants into the sun-warmed soil well before squashes or beans could be planted outside, and kept those plants going well after the garden was ripped out and put to bed at the end of the season. But the little 12-by-24 soon wasn’t big enough to meet our needs.

It was time for a serious high tunnel project. The summer of 2011, with the help of our Northland College intern Sarah, we leveled the top end of the garden and erected a 12 by 50-foot plastic film high tunnel. But you know how it goes—construction projects always take longer than you anticipate. Our tomato transplants were getting desperate—really desperate—dangling and sprawling from their transplant containers, praying for more room for root growth as they waited for us to finish the project. The rafters were up and secured in place, but we still didn’t have the cover on, when the tomato desperation went beyond the beyonds.

It was after chores, and it was dark even for a June night. The summer was getting off to a hot start, and Sarah had been joking about trying “night gardening” to beat the heat. Only the state of the tomatoes made that proposition no joke that night. We pulled the truck up to the high tunnel construction sight, turned on the headlights, and planted 150 tomatoes until midnight (with the help of a few mosquitoes). Sarah didn’t suggest night gardening as a creative idea again after that adventure.

Stringing used baling twine from the rafters down to the plants and securing the strands with ground stakes, the tomato plants were carefully trellised up off the ground in orderly rows with walkways. That next week, the plastic cover was carefully pulled into place, augmented with roll-up sides and a door on the east end. It was a pretty satisfying accomplishment for our woman-powered crew, and the frosts didn’t manage to kill those intrepid tomatoes until November that year. Break out the canning jars!

We’re hoping for such a season now, given the late spring. The twining Romas and colorful heirloom varieties reach high over my head. I love the season of autumn, but it’s always hard to see the demise of the garden, with all the time and love that was invested to help it flourish all summer long. In milder growing climates, like Maine, some farmers are using high tunnels to grow food all year round! But up here, we’re happy to add a bit more time to both ends of the gardening season in whatever way we can. Who can help but smile at the first…and last garden ripe tomatoes? See you down on the farm sometime.