How to Warm Your Garden Soil for Early Planting

As spring begins and that feeling of sunshine and warmth occasionally pops in for a visit or two, it is extremely difficult to resist getting some plants in the garden. Inside, we may know planting season has not quite arrived. The books are telling us to wait. The last frost date is still weeks away. But, it’s just so hard!

Whether you are in the extreme northern climates where snow is obstinately turning to sludge but sticking around or further south where the shorts have already come out a time or two, many of us are yearning for the soil to get a little warmer. Sowing seeds in frozen or nearly frozen ground isn’t too effective.

Well, some things can be done. We can get rid of the snow more quickly. We can raise the temperature of the soil. We can even protect the plants from those sneaky, lowdown late-season frosts that can slay young plants.

Dealing with Snow

Source: Niq Scott/Flickr

If there is snow on the ground, the first goal for warming the soil will be to remove the snow. There are two pretty good options here:

• Option #1: That snow shovel has been hanging in the garage just waiting to be used again. Now could be the time. The advantage of shoveling the snow is that it can be piled around the garden bed like a wall, using the snow to provide a little protection. Creating a sun trap, a crescent-shaped pile that opens up to the south, where the sun is, will also help.
• Option #2: Wood ash is probably the best low-labor option. We, of course, don’t want to put salt or some snow-melt chemical in our garden, but ash helps to melt the snow quickly. What’s more, it can add lots of minerals to the soil once it reaches the surface. That said, it’s important to know wood ash is alkaline, so it may be necessary to add something acidic, such as spent coffee grounds or leaf mold, later to counter that.

Heating the Soil Naturally

Source: USDA Photo by Lance Cheung/Flickr

Though mulch is a wonderful thing for mitigating soil temperature fluctuation, if the long cold winter has frozen the ground beneath it, step one would be temporarily removing the mulch so that the sunshine can reach the soil. Here are some extra steps to take:

• Step #1: Moisture is goin\g to help the soil get warmer faster and stay that way. The bed shouldn’t be drenched, but making sure that it isn’t bone dry is important. Even if it freezes at night, the water will warm up more quickly than the soil during the day, and that will help the soil follow suit.
• Step #2: Large stones (or bricks) along the sides of the beds or even placed periodically through them can assist in the process. Stones have a dense thermal mass that absorbs heat from the sun during the day and then releases that heat at night when the temperature drops. They’ll help the soil get hotter during the day and keep it snuggly at night.
• Step #3: While airy mulch—like shredded leaves or straw—not be the best option at this moment, adding a layer of dark compost over the bed will both prevent the garden soil from drying out and collect more heat, as darker colors do. Plus, this will be infusing the soil with nutrients and valuable organic matter, a benefit for later on.

The Plastic Sheeting Debacle

As with most things these days, plastic has wormed its way into the garden, and without a doubt, clear plastic sheeting can increase the temperature of the soil rapidly, as well as hold that much of that heat in place on chillier nights.

That said, it’s not ideal to go out a buy new plastic sheeting, and it’s worth remembering that plastic can and does eventually leach unwanted chemicals into water and soil. With that in mind, here are some ways to go about the plastic sheeting debacle.

• Look for or save used plastic sheeting. We get all sorts of things that come wrapped in plastic. Mattresses, furniture, appliances, and other big items are often ensconced in plastic. Save that plastic for this kind of occasion. If you’ve already missed that boat, it might be worth checking with shops that sell big items. They might have some lying around.
• Use the plastic for quick results and then adjust. Once the soil has warmed up underneath the plastic, it would then be a good time to turn to these natural methods for keeping it that way. If the soil has warmed sufficiently, it could be mulched again, which would keep it moist, trap the heat that it has already absorbed, and insulate it from any chills that might occur.
• Don’t use plastic to melt the snow. Ash works much better.

Sowing Your Seeds

If the nighttime is still regularly cold, it might pay to build a cold frame, hoop house, or repurposed greenhouse. Regardless, it’s best to start with the veggies that like cooler weather and wait on the tomatoes, peppers, and summer squash. Their time will come soon enough.

Related Content:

• 14 Cold-Weather Companion Plants for the Early-Bird Garden
• 10 Starter Veggies for Your Beginner Home Garden
• 6 Tips to Get Your Home Garden Growing This Spring
• How To Start Your Urban Garden This Spring
• 6 Fruits That Ripen in Spring

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