It takes about three years of vegetable gardening in Maine for a gardener to figure out that a lot of time is spent working in the garden for just a few months of actual food production.

The growing season in Maine is short, too short, with frosts possible throughout May and the first frost of fall usually arriving in September. Maine gardeners have fewer than four months to produce heat-loving crops such as tomatoes, peppers, squash, cucumbers and melons.

Around the third consecutive fall of cleaning up tomato plants killed by the frost, many a gardener says to himself, “I sure could use something to make the season last longer.” Many of us want to plant warm-weather plants earlier than the weather strictly allows and keep them alive for harvesting later. And how great would it be if we could grow greens and other cool-weather crops practically year-round?

Two Maine companies have the answer for extending the season – although the answer for each is different.

Maine Garden Products (stores.mainegarden.com), with offices in Friendship and a manufacturing plant in Howland, sells backyard greenhouses that range in size from 8-by-8 feet to 19-by-54 feet. They have automatic ventilation and watering powered by a solar panel and 12-volt battery.

Johnny’s Selected Seeds (johnnyseeds.com) in Winslow sells some of the material a gardener would need to build high tunnels, also called hoop houses. The key piece of equipment is one of several Quick Hoops benders. As the name suggests, a bender can bend the top rail piece for chain-link fences – available at hardware stores – to create a curved support for the clear plastic greenhouse film that will keep the plants warm and cozy.

Each option has advantages. The greenhouses are made with Maine cedar, have a traditional look that would fit nicely into suburban neighborhoods, and are delivered and installed by the company. All the owner must do is put in the base, which can be as simple as pouring concrete into support tubes (Sonotubes) at the four corners.

The high tunnels, or hoop houses, cost less but require a lot more work by the homeowner, and they look more industrial.

AUTOMATED GREENHOUSES

Maine Garden Products started 16 years ago, with one product – a garden hod, which is used for carrying vegetables and plants. The hod is now sold at the company website as well as at stores like L.L. Bean and Burpee Seeds. It has since expanded its product line.

“We started to build greenhouses because we saw a void,” said Eric Winters, operations manager for the company. “Our greenhouses are built with white cedar, triple walled with poly-carbonate glazing, self-contained and self-tending.”

They are intended for a gardener who wants to extend the season, but also wants to be able to go on vacation occasionally – which is why the greenhouses are equipped with solar panels, thermostats, windows and drip-watering systems that work automatically.

(Maine Garden Products does sell manual versions for less money. For instance, the fully automated 8-by-8-foot greenhouse costs $4,295 while the manual version is $1,000 less.)

Most of his customers are homeowners who use their greenhouses for three seasons, according to Winters. A few owners have added electric or propane heat and used them through the winter, while some have managed to grow greens all winter with no added heat.

Greenhouse gardeners can grow their crops directly in the ground or they can add a floor and grow their vegetables on benches and in containers.

DO-IT-YOURSELF TUNNELS

The hoop houses that gardeners can build from equipment they buy through Johnny’s come in many variations – low tunnels or high tunnels with traditional end walls including doors, or caterpillar styles, in which the plastic covering is gathered at the end.

Creating a season extender with equipment from Johnny’s isn’t as easy as buying a kit, but a gardener isn’t on her own, either; she gets a helping hand. Johnny’s website includes an instruction manual, which can be found by clicking on the picture for the Quick Hoops high tunnel bender. The instruction manual includes an Excel spreadsheet calculator. A gardener types in the size and style of hoop house he wants and the spreadsheet calculates how many of each part is needed, the product number and whether to buy it at Johnny’s or a hardware store.

“It’s a really nice guide of how to put it up,” said Andrew Mefferd, greenhouse specialist at Johnny’s, “and anyone with no background in greenhouses can do it.”

Mefferd, who operates a farm in addition to working at Johnny’s, built a 12-foot wide, 72-foot long tunnel himself that he uses to house chickens in winter. “We call it the hoop coop,” he said.

In warm weather, when the chickens go outside, he plants vegetables in the high tunnel – with the chicken manure serving as fertilizer. This year, he was harvesting spinach from his hoop coop in early May. When all was said and done, he spent about $1,000 to build it.

Mefferd said the customers for the high tunnels are split about evenly between commercial farmers and backyard gardeners, with the former usually building larger tunnels. Most gardeners use the tunnels to extend the growing season, Mefferd said, with a much smaller number using them through the winter.

The low tunnels, which use EMT conduit in place of the chain-link fence railings, cost less than high tunnels but are a lot less convenient because you can’t walk into them.

I interviewed Mefferd as he was heading to a conference on protected agriculture (that’s what people on the inside call growing crops in greenhouses and tunnels) in Connecticut. He was scheduled to speak on which crops that Johnny’s sells grow best under cover.

If enough of you readers decide to “protect your agriculture,” I’ll interview him again to get his seed-selection tips for you.

Tom Atwell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at 767-2297 or at tomatwell@me.com.