It’s late winter, and nature is stirring. Buds are forming on trees and verdant green shoots are emerging from their winter slumber. Gardeners are excited to get their hands in the soil and seeds in the ground. With dreams of baskets brimming with flowers, jars filled with dried herbs and an abundance of herbal remedies gathered right from our backyards, we can wonder, where to start. With building the soil of course!
Building Soil Naturally
In my experience, preparing our garden beds, by tending to our soil, sets the stage for abundance and growth. Without healthy soil we won’t be able to grow healthy herbs. But how do we measure soil health and how do we create it? The answer is simple: we mimic nature.
Looking at the natural cycles of a forest or prairie, we can see that soils are built from the top down. Biomass, which is fallen plant debris, like grasses, leaves, stalks, woody branches, even mushrooms, and lichens, layer on top of the soil. This creates an all-you-can-eat buffet for a diverse array of soil microorganisms to feed off of, live in, and transform the biomass into nutrient dense soil and humus.
The more diverse ingredients added to our microbial buffet, the more microbial diversity we create in our soil. According to the Permaculturist Toby Hemmingway, “the greater the number and diversity of soil organisms, the larger and more diverse will be the flows of nutrients among them as they release the fertility stored in the soil.”1 Wise gardeners can mimic these natural systems in our herb farms and gardens because when we create and tend nutrient rich soils, we grow nutrient rich herbs.
In addition, medicinal herbs have largely remained unchanged from their wild ancestral roots. By mimicking the ecosystem they originate from, we will only help that herb to thrive. So, let’s look at a simple way to mimic natural ecosystems on our farms and gardens.
What is Mulching?
Mulching put simply, is covering bare exposed soil with an organic material. It can be as simple as utilizing any carbon rich plant material and thickly placing it on the soil around the base of our plants.
Types of Mulch for Your Herb Garden
Types of mulch include straw, compost, wood chips, alfalfa, pine needles, nut shells, rice hulls, leaves, slashed vegetation and weeds, stable bedding, and even grass clippings.
I don’t recommend using hay, as it is loaded with grass seeds. I also recommend laying it on thick. The most common mistake I see people make is not applying enough mulch, and weeds just grow right through it. For denser materials like wood chips, apply 3 inches or more and for lighter materials like straw, apply 6 inches or more.
Sheet Mulching: The Cat’s Meow of Soil Building
Sheet mulching, also known as lasagna gardening, is a popular permaculture technique that takes soil building and health to a whole other level. And it is one of the fastest ways to transform the soils in your herb garden. It can be as simple as applying a layer of weed suppressing cardboard topped with 3 inches of wood chips or compost.
This basic sheet mulching technique works great if you are sheet mulching already established perennial gardens. But if you really want to build some amazing soil, try this method:
- Cut back any vegetation in the site you wish to grow in.
- Plant any large crops that require a deep hole (trees, shrubs, and established perennials) and water well. We do this now, to make sure that the large root systems of these plants can establish themselves in the native soil. Then we sheet mulch around them to mimic the natural cycles of soil building.
- Place a layer of cardboard down the whole length and width of your garden bed. Make sure you remove any tape and that you are using brown cardboard only. Do not use white cardboard or pieces with inks and dyes. Newspapers can also be used.
- Sprinkle any mineral amendments you choose to use based on your soil’s needs.
- Add 3–12 inches bulk organic matter: any materials that may have weed seeds like hay or fresh manure can be added to this layer. Examples are: straw, spoiled hay, alfalfa, cut clover, seaweeds, pulled weeds, cut vegetation, and stable bedding. Have both fresh and dry materials. Work with whatever you have access to and make sure it’s diverse. Apply a mixture of these materials covering all of the cardboard.
- Place a new layer of weed suppressing cardboard or newspaper, make sure to overlap any edges so weeds can’t grow through the gaps.
- Apply 2–3 inches of finished compost.
- Apply a top layer of 2–3 inches weed-free carbon rich material, such as wood chips (not cedar or walnut) straw, or leaves.
- Water well and let marinate.
Your sheet mulched garden bed can be planted right away: simply push back the top layer of mulch and plant seeds directly in the finished compost layer. Or you can let this bed rest for a few months, letting the soil microbes do their job.
The Benefits of Mulching Your Herb Garden
Most conventional gardeners spend a lot of time and energy “cleaning up” their gardens by clearing away plant debris from around their plants, which leaves the soil exposed and vulnerable to the elements. Removing this top layer of protection starves the microbes responsible for feeding plants and building soil, and this also increases the need for mined fertilizers, pesticides, and herbicides. This conventional practice also creates erosion, topsoil loss, and destruction of soil structure, which negatively affects plant health. Mulching mimics nature and does the following;
- Builds topsoil and increases microbial diversity and population in the soil, which thus increases nutrient content and bioavailability.
- Prevents erosion from wind and rain.
- Decreases evaporation while holding on to moisture and decreasing the need to irrigate.
- Cools the soil in summer and warms the soil in winter.
- Keeps crops clean by eliminating dirt back-spray on the undersides of leaves.
- Creates habitat for beneficial insects.
- Decreases weed pressure and eliminates the need for pesticides, herbicides, and fertilizer use.
Here are some frequently asked questions about building healthy soil…
When can I sheet mulch my garden?
You can do sheet mulching any time of year, but my favorite times are in late fall to early spring. Not much is growing then anyway, so this gives the sheet mulch bed time to decompose a bit before planting. If I sheet mulch during the growing season, I like to direct seed a fast-growing nitrogen fixing cover crop first, before any long term plantings.
What mineral amendments should I add to my soil?
The mineral amendments you should add to your soil depends on the unique composition of your soil and on the plants you’re growing. One of the best ways to learn more about your soil and its specific needs is to get your soil tested. When first starting an herb garden, I add trace minerals that are naturally leached out of the soil from the rain, some common examples are Azomite, kelp meal, and bone meal. I then focus on increasing the diversity and amount of soil microbes in my soil, so they can cycle the nutrients around and feed my herbs for me.
How long does it take to build healthy soil?
The length of time it takes to build healthy soil all depends on one thing: biomass. And it all depends on how often and how much you are adding a diverse array of materials. The more you can feed the microbes the quicker they can build. I like to grow fast growing herbs like comfrey, which can be cut back several times in a season. Some of the leaves I will harvest, and the rest I just chop and drop on top of the soil. Remember, if you feed the Earth, the Earth feeds you.
What plants should I grow in my herb garden?
If you want to start an herb garden, check out Tara Ruth’s simple guide to starting an herb garden with five easy-to-grow medicinal plants. Tara includes tips for growing these plants as well their medicinal benefits, plus she shares simple recipes too.