The Care and Feeding of Time Machines

The distinction between intensive and extensive food plant production discussed in last week’s post has implications that go well beyond the obvious. When you garden a backyard or a few acres intensively, you can spare the time, energy, and resources to do things you can’t do on an extensive farm of a few hundred acres, and the payback can be spectacular.

This week’s post is going to explore one set of these possibilities. I could be prosaic and give that set any number of labels, but half the fun of the Green Wizard project consists of pointing out the way that many of the possibilities open to us just now stray over the border into the realms of fantasy and legend, so I’ll use a slightly more colorful term for the approaches I have in mind. What we’ll be discussing, then, is the art of making and using time machines.

The gardener’s art, after all, requires a close attentiveness to time, and in particular to dimensions of time that contemporary culture doesn’t grasp as well as it should. We’re so used to thinking of time as an abstract numerical measurement – so many minutes, hours, days, or what have you – that it’s often easy to lose track of the fact that for living beings, time always has a qualitative dimension as well as a quantitative one. In the temperate zone, for example, four o’clock in the afternoon is a completely different time for living things in January than it is in August, and twenty days means something completely different for living things at one season than it does at another.

Skilled gardening depends on these qualitative differences. Most of the best gardeners I’ve ever known made it a habit to go out into the garden first thing in the morning and stand there, hands in pockets, doing nothing in particular except trying to get a sense of what the garden was doing, or ready to do, on that particular day. Most of them also had a collection of ground rules setting out the basic rules of garden timing, with wiggle room so they could be adjusted for the vagaries of weather and the like. Choosing the right time to plant particular crops, in particular, is a fine art, and usually ends up supported by traditional incantations that are handed down from generation to generation.

In the soggy Western Washington climate where I learned organic gardening, for example, it was the received wisdom that you had to get your peas in the ground by George Washington’s birthday in order to get a good crop. Where I now live in the north central Appalachians, in the same way, I’ve been told repeatedly by gardeners that it’s time to plant corn when the leaves on the oaks are the size of a mouse’s ear. Mind you, I don’t know for a fact that there’s an Appalachian Standard Mouse whose ears all the local oldtimers have carefully measured, but I’m not sure it would surprise me.

The differences between one time and another are crucial throughout the annual cycle of the garden, but they become especially so in the earlier and later parts of the growing season, when a few degrees of temperature one way or another can make the difference between successful germination and a failed crop, and the threat of an unexpected frost looms over the garden beds like Godzilla over Tokyo in a Japanese monster movie. That’s when gardeners wish they could somehow conjure up a couple of spare weeks of frost-free weather for spring planting or a spare month of good weather in fall to let some late-ripening crop finish its life cycle.

This is where the time machines come in, of course. Now of course we could call them “season extenders” or simply ways to stretch the number of weeks in which your garden can be productive, but why not go for the more colorful label?

There are two distinct approaches to the care and feeding of time machines, and you can use either or both of them in a backyard garden of the sort these posts are discussing. The first relies on the simple botanical facts that not all plants have the same response to temperature, and that crops with different seasons can overlap quite closely in an intensive garden without interfering with each other at all. The second relies on the equally simple botanical principle that temperature, not day length, determines the season limits for nearly all food crops, and cold – especially freezing cold – is the primary limiting factor over most of the temperate zone, so anything that changes the temperature in and around your plants changes their effective season.

The first time machine, as far as I know, was invented by a forgotten backyard gardener by the name of A.B. Ross, whose 1925 book Big Crops from Little Gardens I’ll be scanning and making available for apprentice green wizards as soon as time permits. Ross found that he could plant his garden in three shifts – “prior crops” of plants that germinate well in spring’s cool temperatures, “main crops” of plants that need summer heat to thrive, and “follow crops” of plants that can handle fall frosts when ripe – and do these three shifts in two rows, planted much more closely together than the ordinary garden practice of his time thought possible. His methods rely on intensive gardening methods – you couldn’t get away with them in a big field – but in their own context, they work very well indeed.

Here’s how it works. First thing in spring, as soon as the soil is workable, you prepare your garden beds and start planting rows of prior crops – snow peas, early radishes, curly lettuce, spinach, and the like – with three feet between each row, putting in a new row every ten days or so, so your harvests will be staggered and you won’t end up with too much of anything to eat at any one time. Once weather permits, you start planting your main crops in rows spaced midway between the prior crops, so they begin to grow while the prior crop is maturing. By the time the main crop is maturing, the prior crop is gone, and you’ve had time to work a little compost into the now-empty rows; that’s when you plant the follow crop for fall and winter – cabbage, kale, turnips, more snow peas and radishes, and so on. By the time these are ready to put on their full growth, the main crop has been harvested. The result is that you get three harvests out of one garden bed.

Ross worked the same trick within individual rows as well, training his plants up poles, for example, to minimize the amount of ground they shaded. The only later book I know of that refers to his method, John and Helen Philbrick’s Organic Gardening for Health and Nutrition, comments that “one sometimes needs a diagram of the plantings to locate certain plants in the jungle that is likely to result.” This has certainly been my experience; it’s the only gardening method I know that results in a vegetable garden as dense as a weed thicket or an old-fashioned cottage garden, not to mention one that bears continuously from late spring through the first couple of killing frosts.

The second way of building a time machine is a good deal more popular these days than Ross’ clever method. It relies on a principle that we’ll be applying repeatedly in these posts – the ability of simple technologies to turn solar energy into useful amounts of diffuse heat. If you’ve ever climbed into a car that’s been left in the sun for a few hours on a hot summer day, and yelped when your arm brushed against a vinyl seat heated to the sizzling point, you know the basic trick: a contained space with a transparent cover that lets sun in, but won’t let heat out, warms up very effectively in the sun’s rays.

That’s the trick that our second set of time machines use. There are any number of methods of applying it, starting with the cloche. What’s a cloche? A transparent, bell-shaped cover with an open bottom that you plump down on top of a plant in spring, before the weather warms. Sunlight streams in through the cloche and warms everything inside – the air, the plant, and the circle of soil within the edges of the cloche – but the heat can’t get back out anything like as easily as it gets in. You can spend a lot of money to get elegant glass cloches with or without little vents on top, or you can take ordinary 2-liter bullet bottles, strip off the labels, cut off the bottoms with a good sharp knife or a pair of snips, and you’re good to go. Cloches are especially useful when setting out seedlings early in the season, when the cold can hinder plant growth and there’s still some danger of frost; by the time the plants are well established and starting to bump up against the limits of the cloche, the weather’s usually warm enough that you can take them off, give them a good wash, and put them in the basement for next year.

The next step up from the cloche is the row cover. What’s a row cover? Imagine a cloche grown long and wide enough to cover a good section of a garden bed – say, eight feet long, two feet wide, and two feet high. Most of the ones I’ve seen and handled have a framework of wood or one-inch PVC tubing and are covered on the top and sides with clear sheet plastic; duct tape usually plays a role in there somewhere as well. You put it over plants you want to protect against cold and frost, just as you do with a cloche. If you live in a windy area, you’ll need stakes to keep it from blowing away; if you live in an area that gets hot sun even in spring, you’ll want to make sure things don’t get too hot for comfort under the row cover in mid-afternoon, and prop it up along one long side to let excess heat get out if this becomes an issue.

Ready for the next step? That’s a cold frame, which might best be described as a permanent row cover. Your standard cold frame has wooden sides and back, and a hinged lid on top, slanted down toward the southern side, that’s made of glass or transparent plastic; the front can be wood or glazing, depending on your preference; the bottom is a garden bed. The colder your climate, the more carefully you have to insulate the back and sides and weatherstrip the opening around the lid to get good results. Think of it as a sminiature solar greenhouse with access from the top and you’ve basically got the idea. Choose the location for your cold frame well, so it will get plenty of sun in winter, and you can get hardy crops from it year round.

The final step in the succession, the ultimate backyard garden time machine, is a solar greenhouse. This isn’t a simple project, and needs to be put together by someone with at least basic carpentry skills. If that’s you or someone you know, though, don’t hesitate, because a solar greenhouse in a good location can have spectacular payoffs, starting with a year round vegetable supply. If you can arrange to have it backed up against a south-facing wall of your home, for that matter, it can turn into a source of solar space heating – we’ll be discussing that in a later post.

The value of all these methods for extending the growing season, and making seven months do the work of nine or more, is simple enough when you remember that the system that supplies fresh vegetables and other nutrient-rich foods to your local grocery store is spectacularly dependent on an uninterrupted flow of cheap petroleum-based fuels and agricultural chemicals. It’s likely to be a while before supplies of bulk grains and dry legumes run short anywhere in North America, but a serious disruption in petroleum supplies – something that could happen for political or economic reasons with essentially no warning – could leave most people in the industrial world scrambling to get access to anything else. Having a thriving backyard garden that keeps you and your family comfortably supplied with vegetables is one kind of security; being able to teach other people in your neighborhood how to do the same thing is another kind of security, and both are worth having.


The two books referenced in this week’s post are A.B. Ross, Big Crops from Little Gardens, and John and Helen Philbrick, Organic Gardening for Health and Nutrition. The latter is readily available; the former is tolerably rare, and (since it’s long out of copyright) will be scanned and posted on the Cultural Conservers Foundation website as soon as time permits.

There are any number of good books on cloches, row covers, cold frames and solar greenhouses. Three books that have been mainstays of my library are Rick Fisher and Bill Yanda’s classic The Food and Heat Producing Solar Greenhouse, William Head’s Gardening Under Cover, and the predictably massive and detailed Rodale Press book on the subject, James C. McCullagh (ed)., The Solar Greenhouse Book. All three of these have detailed plans for solar greenhouses, and the latter two also cover some of the smaller species in the same family of time machines.