Footpaths and/or vehicle access paths are absolutely necessary for any yard. Unfortunately, weeds love growing in them. Worse, the pressure from footfalls, wheelbarrows and vehicles compress and compact the soil, pressing the soil grains together so tightly that oxygen – and therefore life – can’t exist often up to several inches or more deep. Any life, that is, except for the grasses and other weeds that nature sends in to help repair the soil. Bare ground will be greatly compacted by rainfall, which will then erode paths as it runs, unable to soak through that spaceless ground. Once wet bare pathways are often unwalkable until they dry out, and have to be resmoothed. In our hot, dry areas, bare earth or graveled pathways reflect heat and light back up. That reflected heat and light dries out the underside of plant leaves, where species such as Live Oaks have over the millennium developed leaves that curl to expose less surface to the hot sun and to gather moisture underneath. Reflected heat and light dries out the air as well, and any hope of slight humidity to help water plants through months of dry heat is gone. If you have open-pollinated vegetables that rely on breeze for pollination, all that open pathway actually decreases your germination because pollen – such as from corn – will dry out in arid conditions. Humidity that you can keep in your garden will keep pollen more viable longer.
What to do? Covering pathways with gravel is a common solution. I hate gravel. It heats up and becomes a thermal mass in the summer, further cooking your soil and air. It doesn’t suppress weeds and weed-whipping becomes an exercise in avoiding shrapnel. You can never get it out of the ground once you apply it, and chunks of gravel don’t do soil much good for planting. If you trip and fall on gravel it does terrible things to your knees – I had a piece lodged in my kneecap after a stumble some years ago (sorry for that cringe-worthy item).
Covering the soil is better, but not best. Bark will help rain bounce and then percolate, is dark so it won’t reflect light and heat as gravel does, and it decomposes. It is also expensive to buy, and because it decomposes you have to re-buy it every couple of years. Decomposing bark may be adding elements to your soil that you don’t want depending upon the source.
I have experienced all the options above. The best method of countering all these issues that I have found also repurposes and recycles. Sheet mulch. Yep. You’ve heard it from me before and it proves itself every year. There is more to it, though.
First of all, please, please, please never use plastic. You can read about white pollution and the layers of plastic merging with topsoil in China and cringe. Plastic will not last. It will always be around in pieces. You will be poisoning your soil.
At the most basic, you can cover your pathways with 1/2″ of cardboard and newspaper, and top it with wood chips. I obtain my wood chips from arborists who save paying a dump fee by dumping it in my yard. If you’d rather have a more uniform look then purchase your bark. Either way the cardboard and newspaper will make the chips last years longer. More importantly the cardboard and newspaper form a protective, absorbent layer that protects the soil from compaction. Have you looked under a log or sheet of abandoned plywood in awhile? All the white tendrils of fungus, insects, worms, lizards and roots are thriving there along with billions of soil microbes all because they have that protective layer that keeps moisture in and compaction out. That microclimate is what you are forming with cardboard and mulch pathways. Since microbes free up the nutrients in the soil from which plants feed, you are creating more food sources for your plants. Tree and plant roots don’t end at the dripline, they reach out towards whatever source of water and nutrition they can find. If you are top-watering rather than deep-watering, then roots are abundant closer to the topsoil. By sheet mulching pathways you are extending food sources for your plants and trees, which now can stretch underneath the paths, link together with other roots through fungal networks, and become stronger and healthier. You also are creating habitat which is a food source for the entire food chain. Cooler, humid areas are better for bees and insects that pollinate, and the predators that feed upon them such as lizards, toads, frogs and birds. Just by sheet-mulching your pathways you are improving your environment as a whole. How can you NOT want to do this?
Sheet mulched pathways hold moisture and create some humidity which allows for better pollination and helps keep your plants from scorching in arid areas. If you live in a wet area or very humid area, use thicker layers of cardboard and mulch, which will help absorb moisture from the air and deliver it to the ground. Decomposition is quicker in wet areas, so using several inches of cardboard with mulch will last much longer and will again keep down compaction. Compaction in rainy areas is just as bad as in arid areas because of the erosion and flooding it causes.
To catch rainwater and allow it to percolate into the soil rather than erode away topsoil, you dig rain catchment basins or swales. Swales are ditches with level bottoms, and can be a foot long (fishscale swales) or the length of your property. Swales should be positioned perpendicular to the flow of water. You can create swales across pathways, fill them with mulch, top them with cardboard or old plywood, and mulch on top to match the rest of the pathway. Water will be caught in the swales and won’t wash out paths on hillsides.
Going a step farther, you can ‘hugel swale’. Hugelkultur is layering woody material with dirt. This introduces organic material, oxygen and nutrient pathways into the soil and holds moisture into the dry season. You can dig deeply in your pathways, layer old wood (sticks, branches, logs, whatever you have) with the dirt, up to soil level, then sheet mulch. Your pathways are now waterharvesting alleys that you can walk on, and which will really feed your plants. And you just repurposed old woody cuttings.
In very dry areas plants and trees do better in sunken beds, especially those that require a long chill time. Cold settles in holes. Moisture runs downhill, therefore dew will accumulate at the bottom of holes. You can either plant in holes and have your pathways higher, or if you have an established garden (such as I do) you can build up your pathways so that they become slightly higher than your trees and planting areas. We are working on that at Finch Frolic Garden, here in drought-stricken San Diego county.
So before I launch into yet another long lecture, the idea for pathways is simple: sheet mulch with cardboard and wood chips. If you live in a wet area, use several inches of both. If you live in a dry area, use no more than 1/2 inch of cardboard (or else it will absorb moisture from the soil) topped by at least an inch of mulch (no limit there!). If you want make super pathways, bury woody material before you sheet mulch. If you live in a dry area, raise your pathways above your planting beds. If you live in a wet area, lower your pathways so water can drain away from your plants (unless they love wet feet). Never use plastic, and please rethink gravel.
Then sit back and enjoy your yard and all the food and nutrients and abundance you have set the stage for, all using recycled materials that will last for years. Congratulations!