Leave Roots Where They Belong: Underground

The end of the gardening season is slowly approaching. Although we still get a few warm days—sometimes even heat waves in September!—the nights can already be cool enough to warrant putting on a sweatshirt or even a coat!

In any case, the garden is showing signs of the coming fall. Under the influence of the cold and shorter days, some plants stop growing, while others even begin to lose their leaves. The season of colors is setting in, and with it comes the famous “fall cleanup“!

Down With Fall Cleaning!

Those who know me know that I want nothing to do with fall yard work: cutting back perennials, removing their foliage, raking up all the fallen leaves… all that just to get bare, “clean” ground. First, because I have other things to do—like enjoying the beautiful fall days (and the last fishing trips!)—but mainly because it’s not only unnecessary, it’s downright harmful to the garden!

Yes, you read that right: harmful! Those stems and leaves we remove are valuable organic matter. They protect and nourish the soil, keeping it well structured and alive, and in turn, the soil nourishes the plants and provides them with a healthy habitat.

In the Vegetable Garden and in Containers Too!

Some might say, “Okay, Mathieu, you don’t clean up your flower beds, but surely you do it in your vegetable garden, pots, and planters?” Well, no! I leave as much organic matter there as possible. The only exception is diseased plants, which are best removed to prevent their diseases from spreading the following year (and even then, I do the bare minimum).

The vegetable garden also needs all this richness! Even the dead stems in my pots can serve as shelter for beneficial insects. So I leave everything in place and don’t think about it again until spring. Only then do I pull up a few stems and clumps of roots, and place them on the ground if they prevent me from sowing or planting.

Not for Everyone

I understand that we don’t all have the same tastes! Personally, I much prefer a messy garden, with its dried stems and flowers, dead leaves littering the ground, and plants that grow without following the original plan, to a garden that is too manicured.

For those who prefer to do a little maintenance, it’s always possible to compost garden waste to enrich the soil, shred autumn leaves to make a nice “clean” mulch, or hide dead stems in a corner of the garden, out of sight. It’s a little more work, but the result is almost the same.

Leave Roots Underground

But please, leave the roots of annual plants where they are: underground!

They are an invaluable source of organic matter that nourishes the soil even better than the residues left on the surface. Too often, we pull up roots thinking we are “cleaning” the garden, when in fact, even after they die, they continue to play several essential roles: storing carbon, nourishing microbial life, structuring the soil, and limiting erosion. Leaving them in place also avoids unnecessary soil disturbance.

The Right Material in the Right Place

When organic matter is left on the soil surface—dead plants, tree leaves, dry stems—it acts as mulch. Mulch protects the soil from the vagaries of the weather, wind and rain erosion, and weed germination. This organic mulch decomposes thanks to microbial fauna and flora, insects, and small animals that feed on it. They transform these residues into nutrients that can be assimilated by plants. This is very beneficial, but the process is quite rapid and some of the carbon contained in this organic matter is released as CO2 into the atmosphere, rather than being stored permanently in the soil.

When your annual plants—flowers and vegetables—die at the end of the season, even if you remove their leaves and stems, you can still leave their roots in place. The carbon and nutrients they contain are found directly in the rhizosphere, the area of soil where living roots and microbes are found. This is where decomposers work, but also where active roots draw their resources. By leaving the roots in place, nutrients are released where plants need them, limiting losses through leaching or volatilization.

Stable Carbon Source

Carbon is the backbone of soil organic matter. It acts like a sponge, retaining water and nutrients—such as nitrogen, phosphorus, and sulfur—until plants need them. It is also the glue that binds soil particles together into aggregates, giving the soil a good structure, facilitating the circulation of air and water to the roots and allowing them to develop better.

Carbon from roots persists longer in the soil than carbon from the above-ground parts of plants. Studies show that carbon from roots is 3 to 5 times more effective at binding to the soil. By being directly incorporated underground, it is more likely to bind with surrounding minerals. Once stabilized in this way, it is slowly released over time, nourishing the soil in a sustainable way.

Underground Reinforcement

In addition to providing carbon, which helps structure the soil, dead roots act as an underground framework that holds the soil together even before they decompose. This is easy to see: when you pull on a clump of dead roots, a whole section of soil comes with it. They therefore offer natural protection against erosion.

Then, once decomposed, they leave behind a network of small channels that improve aeration and water infiltration, while serving as passages for future roots and soil insects.

Less Soil Disturbance

We have seen how dead roots act as a reinforcement that holds the soil together, as conduits that improve aeration and water infiltration, and as a source of binding carbon that helps soil particles aggregate.

In addition to these physical and chemical roles, leaving the roots in place also helps preserve mycorrhizal networks. These underground fungi form vast filaments that attach themselves to plant roots and exchange water and nutrients with them, benefiting both. Pulling up roots breaks these networks and slows their development. Leaving them in place gives them time to reform and recycle naturally.

Not to mention that unnecessarily disturbing the soil disturbs earthworms, springtails, and burrowing insects—all organisms that create tunnels and recycle organic matter.

Another Task to Cross Off the List

So I’ll spare you another pointless task! As is often the case in the garden, less is more. So rather than breaking your back pulling up roots, put on your best wolf-print sweatshirt and head into the forest to admire the landscape lit up by the colors of fall.