As loathe as I am to start talking about putting the gardens to bed, especially when it’s 80 degrees as I write this column, I am acutely aware that the days are getting shorter, nights are slightly cooler and eventually, it won’t feel like a gloriously balmy summers day.
I am also aware, as are we all, that the monsoon was more of a non-soon this summer, at least for Southwest Colorado and Northwest New Mexico. This has been one of the driest summers on record, as evident by all the tragic wildfires across the western slope.
One of the questions I received quite often this summer was about the damage high temperatures and smoke can have on our gardens. We know that combination is terrible for humans, but perhaps we are less aware of the impact that it has on our plants and consequently our soil.
When temperatures were staying at or above 90 degrees for days on end and the smoke was driving a lot of us indoors, our plants did not have that option. Biology is so fascinating, when temperatures are sustained above 90 degrees, most plants experience a great deal of stress. Plants have pores in their leaf tissue called stomata, these function to protect a plant, when the temperature is high, the stomata close to prevent water loss, or transpiration. But one of the side effects of keeping stomata closed longer than normal is a decrease of absorbing or ‘inhaling’ CO2 and limits their ability to photosynthesize. When a plant photosynthesizes, it is converting that solar energy to glucose/food for survival. You may have noticed droopy, curled leaves or the tips of leaves browning when the heat was so high, even if you increased watering.
The smoke exacerbates the issue, often reducing how much solar radiation can reach the leaves, further reducing how well they photosynthesize. We must respect the hard work a plant puts into growing (yes, you should say thank you to your flowers, veggies, and trees) in our climate, just imagine trying to grow in Phoenix in the summer, now that’s a trooper.
So, what does all of this have to do with my title about cover crops? Bet you forgot that part, huh. Well, when the environment is functioning at a high stress level, our soil can suffer as well. Have you ever played the game where you aim an infrared thermometer at a white car and then a black car and see how extreme the temperature difference can be? Well, the same is true for dark, bare soils. Extreme heat causes rapid evaporation and can even lead to a loss of soil microorganisms within that top layer.
We can help by putting shade cloth or arbors over our plants, which I highly recommend. Or use a nice light mulch or light-colored gravel to hold in some of that soil moisture and lower the soil temperature, heck, even letting the weeds grow a little can protect the soil surface.
One of the ways we can support healthy soils is through cover cropping, which can be very beneficial if you have raised beds. It is easy to forget that when we water a raised bed year after year, that soil is draining the nutrient rich goodness right out the bottom over time. I have seen some gorgeous beds lose their vigor and become rather compacted. That is a good indicator that it’s time for a boost.
The reason farmers use cover crops more and more often is to build soil fertility. The mixes can very widely, but the concept is the same, introducing plants that add nitrogen (clover, alfalfa, peas), root structure (radishes, oats, barley or wheat), and good ol’ fashioned biomass comes from all of the above plants, and so many more. I also love to include flowering plants in my mixes like wildflowers that will draw in the pollinators in the early spring.
Seeding your backyard or front yard gardens, raised beds or even your dying turf lawns with a cover crop mix can create an amazing biome for future gardens. You might love the look (and decreased use of water) so much that you chose to let it become your new lawn. That makes you a soil superhero, I can almost hear the earthworms cheering from here.
So, whether you love a good hot summer, or frigid winter, the seasons are still moving on and this is the best time of year to get out there with some cover crop seeds, rake them in, cover with a little straw, water them in and see what awaits you in the spring. Happy Gardening.
Heather Houk is the Horticulture and Agriculture specialist for the La Plata County Extension Office.
