Plant Seeds Now, Using a Cold Frame

Giordano’s has gotten in new seeds for spring. Because people know there are several months to go before the earth will be ready to be planted, they assume they have to wait. But you can actually plant seeds now if you have a cold frame to help give plants  a head start.

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How Does The Cold Frame Work?

A cold frame creates a microclimate that provides several degrees of air and soil temperature insulation, and shelter from wind. In cold-winter regions like ours, these characteristics allow plants to be started earlier in the spring, and to survive longer into the fall and winter. They are most often used for growing seedlings that are later transplanted into open ground.

The cold frame has no artificial heat added. The temperature difference between the inside and outside of the frame is generally not more than 5 to 10 degrees. A mat or blanket may be placed over the frame on cold nights to conserve heat, which increases temperature by only a few degrees, but there are times when a few degrees can be very important.

Relying solely on the heat and warmth of the sun, a cold frame costs nothing to use, and Giordano’s has them in kits, or already built to take home and place in the best spot to give your semi-hardy plants a fighting chance.

So What Can I Do Now?

You can start your seedlings inside, in a sunny window, and in a month or so place inside the cold frame to “harden off” seedling plants or to start cold-tolerant plants such as pansies, cabbage or lettuce earlier than they can be started in open soil. When you start your plants in the cold frame they will mature sooner than those planted directly in the garden. If you are sowing directly into a portable cold frame, have the frame in place two weeks prior to seeding to warm the soil for germination.

Whether you are starting seeds in flats or sowing them directly into the soil, a portable cold frame eliminates the transplanting shock that many plants face because they will be better acclimated from the outset. If you are seeding in the early spring, focus on cool-season plants, as they tend to have lower temperature thresholds for germination. Keep in mind that seedlings are more susceptible to extreme weather conditions than established plants.

Whatever method you are using to start your seeds, make sure to keep the seedbed evenly moist. Once seedlings have germinated, the cold frame should be vented more frequently to discourage damping off, by increasing air circulation.

If you start your seeds in a greenhouse or indoors under lights, you can start them a good six weeks earlier than usual and transplant them to a cold frame you’ve placed in your garden. Again, you will need to pay attention to the degree of sunlight, moisture, temperature, and wind. The frame also provides a windbreak while the plants are still small.

Because you’re encouraging active growth, you will want to use a transparent cover of plastic or glass. The soil will dry out more quickly inside the cold frame than outside, so be sure to keep the soil moist, especially while the plants are acclimating to their new site. Keep in mind that more plants die of excessive heat and drought in cold frames than from cold damage. Proper ventilation is particularly important for cool-season plants. If you have established transplants, vent the frame when the outside temperature is 40°F or higher.

If your plants are closer to the seedling stage, you may want to wait until the outside temperatures are 45°F to 50°F before venting.