Drought-Tolerant Plants: The Earth-Friendly Herb Garden
Low-water garden strategies make a huge impact in the sustainability of farms and gardens, which is becoming an increasingly important matter to consider. Drought and dropping water tables makes this a necessary shift that many growers will need to adapt to. It is of great importance that we, as herbalists, gardeners, and land stewards, be mindful of the water resources, or lack thereof, in our local environment. Many herbalists demand or prefer organic standards, but it is also vital that we cultivate and support sustainable herb growing methods as well — including growing drought-tolerant plants.
Where I live, in Arizona, it is especially important to adapt watering and gardening methods to conserve this vital resource. Implementing sustainable growing practices saves water and also supports the health of the soil network and the root systems of the plant, making it much stronger to withstand drought and intense temperatures. These techniques can be adapted to other regions that may be experiencing low rainfall, local water restrictions, or simply to implement more sustainable practices in the garden.
Growing a garden with drought-tolerant plants is a great way to practice sustainable gardening.
Choose Drought-Tolerant Plants Wisely
If you have depleted or restrictive water sources, choosing plants that will be able to withstand drought-like conditions is a logical first step. Luckily, many common herbs will do fine with less water. Even if you have an ample water supply, it is really important just to consider if your watering practices are inefficient or wasteful. Sometimes this means examining what species of plants are best and the quantities of them that we choose to grow. It is so difficult, and maybe impossible, to evaluate how much water a plant might be “worth,” but sometimes we have to make practical decisions when it comes to growing plants in a low-water environment.
Specific medicinal plants that are typically considered drought tolerant or have low water needs are lavender, Echinacea, yarrow, sage, mullein, California poppy, juniper, Aloe vera, Moringa, lemongrass, safflower, ashwagandha, olive (leaf), chaste tree, yerba santa, goji berries, white sage, Calendula, creosote, oregano, epazote, brittle bush, senna, wild lettuce, thyme, Mexican elderberry, and rosemary.
These may not survive in all climates, but many are incredibly adaptable and worth trying to grow, especially where water sources are extremely limited. Some will live for many years and bring abundant medicine continuously, even with minimal water.
Gardening with drought-tolerant plants can help you conserve water more easily.
3 Reasons to Adapt to Drought-Friendly Gardening Methods
Conserve Water Resources: Of course we should all protect the Earth’s water resources. We should use less where we can, and use it wisely! Becoming more conscious of water usage could decrease your ecological impact and your water bill.
Encourage Plant Resilience: Low-water gardening increases the efficiency of water usage, and it also encourages deeper, stronger roots for the plant. By watering deeper and less often, the roots of the plants tend to reach farther into the Earth, breaking through deeper layers of the soil to find water. Rather than developing a shallow root system, they learn to adapt and create tolerance against harsh conditions, such as drought. Other water-wise techniques support a vibrant living soil system that builds plants’ inner resistance to better tolerate stress. (Yes, plants get stressed out, too!)
Increase Aromatics, Flavor, and Potency: This is a most rewarding aspect of using less water: more flavor! Although there are certainly exceptions, generally many herbal plants will have more concentrated aromatic and medicinal components when exposed to a low-water environment. James Wong, a botanist in the UK, encourages growers to purposely limit watering of herbs to maximize flavor and potency. He states, “Drought stress has been demonstrated dramatically to boost the content of aromatic compounds in a wide variety of herbs. Just as well, most herbs hail from semi-arid regions of the world, making them ideally adapted to cope with this.” 1
There are so many complexities to growing plants in low-water conditions. Each environment is so different, and plants vary greatly in their preferred soil conditions and water necessities. This is a very broad subject, with many different perspectives and diverse experiences. These are the methods I have found to make the biggest difference in my own garden.
Deep watering strategies can help support plant health.
Deep Watering Strategies
This is by far the most important aspect of encouraging drought-resistant plants. Low, slow watering techniques that really saturate the deep levels of the soil are crucial to growing healthy drought-tolerant plants with the least amount of water. Rather than giving plants a little water every day or so, deep saturation, less often, is a more sustainable strategy. Although all plants are unique and some will need a more constant water supply, many common medicinal plants will benefit from a watering schedule that prolongs the time in-between watering. In fact, many herbal plants will absolutely thrive in these conditions, as they don’t like to have overly soggy roots.
Strategic contouring of growing areas can help to passively “capture” rainfall and guide the water flow and optimize irrigation systems. When there is diminished organic matter in the soil, saturation levels can be low and it is important to direct this flow of water to assure it is going down into the root system, and not running off and away from the plant, or pooling too closely to the base. Many plants do not like their trunks or stems overly saturated, and can in fact be drowned or left susceptible to pathogens and pests if the water flow is not directed properly.
Digging a shallow circular well, kind of like a superficial moat, around the plant can help the water saturate right where the plant needs it, discourage water runoff, and protect the stems of the plant from oversaturation. A plant well needs to be at the root zone of the plant, typically as far as the branches reach out, and sometimes adjusted as the plant grows larger.
Strategic contouring can help optimize irrigation systems.
I generally fill the well with a larger grade of mulch, which allows the water to flow down and gives added protection from heat and drought. I also like to dig trenches in front of or behind garden rows and either lay water lines in the trench or use it as a type of irrigation canal if I must water by hand. This greatly reduces the erosion of soil directly around the plant stem and optimally guides the flow of water.
Watering through drip irrigation saves time, energy, and water. It does not need to be a complex system to be effective. Drip irrigation will typically reduce erosion and salt build up in the soil, which are major concerns in most low-water environments. I have often used a very slow running hose to deep water individual plants. This approach is quite effective, but also very time consuming. Watering in the late evening and early morning, especially in hot weather, can also reduce evaporation and salt buildup in the soil, and lessen overall water usage.
A gradual change in watering practices is a good place to start, especially in established gardens that might be accustomed to frequent water. A sudden drop in moisture levels could shock the plant especially if they have a shallow root system. Also, for germinating and transitioning young seedlings, more frequent, shallow watering will be necessary until they develop a deeper root system that can sustain growth with less water frequency.
Mulch can help the soil beneath it retain its moisture more easily.
Organic Matter, Mulch, and Microbes
Healthy gardens begin with healthy soil. Although drought-tolerant plants differ greatly in their soil preferences, they all have the common need of a healthy soil system. Many medicinal plants do quite well in poor soil, with low organic matter, and will need little amendment other than occasional mulch.
Other plants require rich soil and will need more frequent attention to consciously build a vibrant soil system and may need additions such as specific nutrients and microbial inoculations. The presence of beneficial fungi, such as mycorrhizal fungi, help to increase the health of the plant, soil nutrient bioavailability, as well as help them to become more drought resistant.2 These important fungi form symbiotic relationships with the roots of plants and are valuable to the healthy growth of many edible plant species.
Other supportive microbes (bacteria, fungi, protozoa, etc.) need a constant supply of organic matter to feed on, in the form of compost, vermicompost, mulch, leaves, straw, etc. Adding organic matter and mulching plants regularly has so many other incredibly important benefits, it’s value cannot be overemphasized.
Mulch serves as protection from extreme weather and helps the soil underneath it to hold on to moisture. Over time, this creates a vibrant, living soil that is rich in bioavailable nutrients from the constant exchanges between microbes within the soil system. You can even plant living mulch or cover crops that can serve the same purpose, promoting a healthy soil system.
Interplanting
Interplanting can be as simple as sprinkling a few beans to grow around the base of another plant or as complex as creating an entire backyard forest! This idea is common in ecology emulation and Permaculture-type growing systems that emphasize a multitude of plant heights and growth patterns cultivated together in strategic ways. It may seem that growing more plants in one area would increase water needs, not reduce them. Although in some situations this is certainly true, especially with certain plant species, by providing the different “layers” of what would be considered part of a forest ecology, overall water usage can often be reduced.
Jerome Osentowski, a permaculture and greenhouse growing specialist in the arid landscapes of Colorado, says, “By growing plants in groups at many heights and levels both above and belowground, we better use all the available soil moisture and light coming into a given space. Nature’s model of keeping the ground covered to provide habitat for soil-building organisms shows us how to mulch our plants, while creating a backbone of perennials in all our cultivated systems and makes them more resilient.” 3
Although some plants do not get along well with others, many plants benefit each other and can commingle in the root zone and share in water and nutrient availability. Planting ground covers, low-growing herbs, and non-invasive grasses helps to retain the water in soil and reduce evaporation. These plants can be trimmed regularly and added back into the soil, perpetuating the health of the soil system and increasing water retention.
The upper canopy of plants creates a sort of nursery for younger, more delicate plants that may not survive on their own. This same thing occurs naturally in desert environments and creates an entire biome of plants and creatures all dependent on each other for survival. 4
Protecting plants from overheating, water runoff, and erosion can be seen in low-till and no-till strategies that preserve the structure of soil layers and retain organic matter. Accumulation of decaying root systems and dead leaves increases the absorbability and water retention of soil 5 and feeds the organisms present in a healthy soil system. This layering, over time, mimics what happens in the natural cycles of death and rebirth of a variety of plants in an ecological system.
Growing drought-tolerant plants can be a helpful, earth-friendly practice.
Supporting Earth-Friendly Solutions
Integrating sustainable growing practices and water-wise solutions can benefit any garden or farm, especially when it comes to growing medicinal herbs. Getting to know the individual plants and their particular watering needs is vital, and may give insight to seasonal shifts, growth patterns, and best harvesting practices. Watching the world change around us and noticing patterns within the seasons and how they interact with cycles of the plants helps to tune into the Earth around us and connect with the medicine of plants in a very deep way. Working with drought-tolerant plants is one powerful way to support earth-friendly growing practices.
Footnotes
- Wong, James, Grow for Flavor (New York: Firefly Books Inc., 1981), 183.
- Nyle C Brady and Ray R. Weil, Elements of the Nature and Properties of Soils (New Jersey: Prentice Hall, 2010), 343.
- Jerome Osentowski, The Forest Garden Greenhouse (White River Junction, VT, 2015), 165.
- Jay Withgott, “Botanical Nursing: From Deserts to Shorelines, Nurse Effects are Receiving Renewed Attention,” BioScience, Volume 50, Issue 6, (June 2000): 479–484, https://academic.oup.com/bioscience/article/50/6/479/260998
- Jay Withgott and Scott Brennan, Environment: The Science Behind the Stories (San Francisco, CA: Benjamin Cummings, 2008), 234.
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