After struggling through a winter of grocery store greens and frozen produce, I don’t want to wait until June to enjoy fresh vegetables. Just because there might be snow on the ground doesn’t mean planting has to wait for months.
Nearly two decades ago, I moved from Ohio to Montana and quickly learned that, if I wanted fresh food before the middle of summer, I had to rethink my gardening techniques. The hallowed “last frost date” became a guide, not a law.
From the ground up
When the ground is frozen, even the hardiest seed won’t do a thing. If it’s cold and wet, the seed might even rot before it ever has a chance to grow. The key to germination is to plant seed in soil that’s warmed to 65-75 degrees. But in the frozen North, how do you get that soil warm enough, early enough? One easy method is to spread clear plastic over the soil, burying the edges to keep it in place and lock in the heat. Even if daytime temperatures hover in the 40s, the sun’s energy can heat the soil beneath the plastic to a whopping 125 degrees. Keep the plastic in place until you’re ready to plant. If your early season garden plot is a raised bed, so much the better. Soil in a plastic covered, raised bed will warm faster.
When growing heat-loving crops such as melons, peppers and cucumbers, it’s especially important to pre-warm the soil. Transplanting these crops through black plastic, which will keep the weeds down and the soil temperature up, helps ensure success in the north.
When you don’t have a greenhouse
Many gardeners dream of a permanent greenhouse; they take up valuable space in the yard and can be expensive. But most of us can find an area for at least one cold frame. This structure can be a simple, bottomless wooden box built with an angled, window-like top to gather the sun’s energy. Many cold frames are painted dark green, black or brown to absorb solar heat. Before planting inside a cold frame, keep the lid closed for several weeks to warm the soil.
A reasonable cold frame size is 3 by 4 feet, which is easy for one person to move, although permanent frames can be much larger. Just be sure you can reach the internal growing spaces without the need to climb inside.
When I’m really organized, I plant lettuce, spinach or mâche (an old European winter favorite) in August, and set the cold frame over the plants when the weather begins to freeze. It’s a bit of a challenge in early fall when daytime temperatures are warm because you will need to open and close the lid for temperature control. But once the cold weather sets in, I keep the lid closed, which keeps the plants growing into early winter.
By the time March arrives, the sun warms the dormant plants in the cold frame and brings them back to life. Some years, I’ve harvested tender new greens by the first day of spring.
Even if I wasn’t organized enough to plant at the end of the season, the soil under the cold frame warms sufficiently in late winter to offer the seeds a chance to germinate. They don’t germinate as quickly as those planted later in the spring, but with sunny days it doesn’t take long to have fresh greens for dinner.
For an extra-early jump on the season, you can position the cold frame over a bed of fresh horse manure, which produces heat as it composts. Be sure to place a sheet of perforated plastic over the manure and layer several inches of soil on top of it to keep the roots of the new plants from reaching the hot manure.
Water the young plants inside the cold frame lightly in the mornings when it’s dry. Moisture doesn’t evaporate as quickly in the cold frame as outdoors, and wet roots in cold conditions aren’t good for most garden plants.
After the initial fix of cold frame-fresh greens, it’s time to think about other garden crops. Broccoli, kale, cabbage and cauliflower are ideal choices to transplant early, since their leaves can actually freeze for a short period of time and still recover. But don’t simply plant them out in the open and hope for the best. Even these durable vegetables benefit from a little protection.
Plastic tunnels and floating row covers are two invaluable tools to keep hardy garden vegetables happy. They create a warm microclimate, which protects transplants and seedlings from the cool and wet springtime weather. The frost protective blanket protects the plants to 25 degrees, while the plastic tunnels typically keep them safe above 28 degrees. For particularly cold nights, toss a blanket on top for additional protection.
Floating row covers, also known as garden quilts, are made from lightweight, polyester or polypropylene fabric that can be placed directly on top of the plants. But, for early spring use, I prefer to use a support system to keep the material off tender plants, such as tomatoes and squash.
Secure support hoops, whether made from wire or arched PVC pipes, by pushing them firmly into the ground roughly 2 1/2 feet apart. Since both plastic and other row-cover fabrics are light, it’s imperative to secure them with landscape pins or staples to prevent the wind from blowing them into the next county.
One drawback to covers is the need to remove the material to water the plants. This can be remedied by placing a drip hose alongside the plants before enclosing them. Later in the season, it’s best to remove the material during the day to allow pollinating insects to reach the blossoms.
The beauty of the floating row cover is it allows 85 percent of sunlight through and doesn’t tend to overheat. However, like a full-sized greenhouse, the plastic-covered field tunnels can overheat rapidly. Be sure to open up the ends by pinning them to the hoop with a clothes pin to allow proper ventilation.
Walls filled with water
Tomato-lovers take heart, with the invention of water-filled, plastic tipis impatient gardeners can plant their precious crop up to eight weeks before the last frost date. Water tipis, which absorb the sun’s rays during the day and gradually release the heat during the night, also work well for peppers, eggplant and other crops that thrive in warm temperatures. Look for the Wall-O-Water or Kozy-Coats brands.
Plant the seedling in the pre-warmed soil and cover with an inverted 5-gallon bucket. Place the tipi around the bucket and use the garden hose to fill each cylinder to within a few inches of the top. Pull up the bucket, and the tipi will close upon itself, creating a temperate environment for the plant to protect it from cold, wind, rain and even snowstorms. I’ve had late-season blizzards shock the rest of the garden, while my tomatoes pulled through with flying colors.
As the plants progress, prop open the enclosures with stakes or wooden crochet rings to allow the plant to grow through the top. The tipis can be removed once there is no risk of frost, or they may be left on through the summer. At the end of the season, rinse them with a mild bleach solution to kill any mildew and reuse for many years.
Just as the name implies, these are large, clear umbrellas that are placed over the top of plants with the center rod set several inches into the ground to keep it firmly in place. Once pushed far enough into the soil (which can be challenging in compact ground), they can withstand 50-mph winds.
Before using solar umbrellas I never harvested an eggplant, because our spring was too long and cold, and summer was too short. There is plenty of room for four or five plants beneath one umbrella. I like using the solar umbrellas over squash and melon plants to give them an extra boost before they outgrow the space.
Umbrellas are most effective in the three or four weeks before the last frost date when nighttime temperatures are too cool for plants to thrive, but typically don’t drop below 30 degrees for very long. Filling plastic jugs with water and placing them inside the solar umbrellas can offer an extra degree of warmth.
Solar umbrellas are available in a number of styles, including solid umbrellas that look like a typical umbrella you’d use in a rainstorm, and styles with zippered vent openings that can be kept over the plants the entire summer. Drip irrigation is handy for watering, although the umbrella needs to be removed to allow proper pollination later during summer. Just remember to secure it in place in the evening so it doesn’t end up down the road.
The next best option to solar umbrellas is to use a gardening bell, or cloche, to protect individual plants. Originally, cloches were made of bell-shaped glass. They offer a pretty, classic look to the early spring garden, but they’re expensive and fragile. Instead, many gardeners opt to use translucent plastic jugs or waxed-paper caps (also called hot caps).
To use the jugs, simply cut off the bottom and push it over the planted seedling. Remove the lid to provide ventilation, and keep the jugs on the plants until they outgrow them. Unless there is drip irrigation running along the plants, each jug should be removed for watering instead of dousing the plants through the opening.
Like solar umbrellas, both the plastic jugs and hot caps are best used toward the end of the spring season since they don’t have a way to retain heat like the Wall-O-Waters. They’ll protect plants from a frost, but a hard freeze might be too much. In that case, toss a blanket over the jugs or hot caps to offer additional protection.
Planting as early as possible is a challenge, but the rewards far exceed the effort. By utilizing a few, or all, of these techniques, it’s possible to enjoy those first tomatoes or peppers weeks before your neighbors.