Gardening With Robin

~~ Gardening with Nature:  Water in the Garden ~~

In these first days of summer, Lunenburg has been experiencing a heat wave and abnormally dry conditions due to the recent lack of rain.  When I go outside to check on the gardens and animals, I walk on brittle lawn paths that crunch under my steps.  I notice some of my herbaceous plants have wilted-over rather than standing upright and I even see tips of young trees and shrubs turning brown under the stress of the heat and lack of water.  If I look at other places in my yard, however, the plants are still green, vibrant and growing.  What creates this difference?  Access to water, of course.

I try to limit my dependence on the Lunenburg town water supply, but once I am out of stored rain water, I do use the hose or carry buckets to water my annual vegetables and any newly planted perennial plants and trees that haven’t had the time to establish a good root system.  I try to do this in the early morning before the sun is high to reduce evaporation. I also try not to water daily, preferring to water deeply at the base of the plant and then wait.  Less frequent, deep watering encourages many plants to send down deeper roots.  I also fill containers with kitchen sink “gray water” from rinsing fruit, vegetables, and dishes to pour at the base of perennial, non-edible flowers in my front yard.  I do not use the gray water that rinsed raw meat or contains any harmful products in it, such as bleach, chlorine, borax, or cleaning products other than biodegradable dish soap.  For all of my other plantings, I rely onprecipitation.

In a normal year, Lunenburg receives abundant precipitation, between forty and fifty inches a year.  The challenge for gardeners is to capture that abundance and make it available through the drier times. Depending on your situation, you can capture rainfall in rain barrels, ponds or, as in healthy ecosystems, the soil itself.  Here are several ways I use to increase the capacity of my soil to capture and retain water:

Build healthy soils

A fertile soil, containing a high level of organic material, will hold significant amounts of water because humus acts like a sponge, absorbing and storing water in the soil until the plants and organisms use it.  In nature, animals, fungi, bacteria, and other microbes living in the soil all break down living matter – such as the leaves that fall from the trees in autumn – leaving the organic matter that is most difficult to break down, humus, in the soil.  If you want healthy soil, protect and feed diverse organic matter to the microbial community living in your soil.  By adding organic matter on top of the soil on a regular basis, like the leaves and twigs that fall from trees in the fall, you are providing nourishment to the soil microorganisms; if you deny the soil organic matter, these organisms will be so hungry, they will even eat the humus in your soil and the soil will lose its capacity to hold water.

If soils are compacted, the heavy rainstorms we get in the summer tend to just run over the surface, particularly on slopes, rather than sinking into the soil where gardeners want it.  The structures built by soil organisms in the process of breaking down organic matter for food allow rainfall to easily penetrate the surface.  Every time you disturb the soil, such as by tilling, you disturb that structure and the community of soil organisms has to recreate it.  If you disturb the soil too often, you will end up killing the soil community necessary to keep soils healthy and alive.  For this reason, I try to disturb the soil as little as possible, only digging holes where I want to introduce new plants and, rather than digging up old plants when they are finished, I just cut them down at the surface, leaving the roots to decompose and leave channels for the water to follow down deep into the soil.  Rather than disturbing the soil by tilling, encourage biological tillage by plant roots, earthworms and other soil critters.  As much as possible, do not walk on garden soil as you do not want to compact it.

Use thick layers of mulch to moderate temperature and reduce evaporation from the soil

Remember that microbial soil community we talked about?  Wide swings in temperature and moisture levels make the soil a less hospitable place for them.  To protect them, I use a variety of mulches, depending on what is available and where I need it.  When I have them, I use ramial wood chips, shredded leaves, pine needles, compost, vigorous green vegetation that I need to cut back, grass clippings, spoiled hay or cover crops (living mulch) like buckwheat, vetch, clover, mint, or even strawberries.

I do not dig the mulch into the soil. I lay it on top and rely on the soil workers, like the earthworms, to mix it into the soil as they work to decompose it.  Wood chips and pine needles encourage fungal communities in the soil, which is great for trees and shrubs.  Grass clippings and hay encourage bacterial communities to live in the soil, which is great for annual vegetables.  In places where I grow vigorous herbs, I cut them down and either let them fall or lay them down on the ground where I want them.  This provides me with free mulch, multiple times in the growing season.  This practice is known as “chop and drop.”  If you grow these plants close to where you need mulch, you have eliminated the job of hauling mulch.  Remember, if the mulch you choose has seeds in it, they may germinate in that area, so consider if what you are using is appropriate to the place.  Some types of mulch, such as pine needles, may also change the pH of the soil if they are used exclusively or in large quantities.

Plant dense combinations of plants

If you look at part of a non-irrigated lawn shaded by trees and compare it with a similar part located in full sun, you may notice that the shaded part of the lawn is greener and surviving better in this hot, dry weather.  The leaves of trees help protect the grass from temperature swings, slow evaporation, and also slow down the water in a heavy rainfall, allowing more of the moisture to be absorbed by the soil.

By choosing plants that do not directly compete with one another but work together to continually shade the soil and help smother unwanted plants, you can protect garden soil the way the tree helps to protect the lawn.  Apple trees, for example, have relatively shallow roots, so if you plant herbs with deep tap roots near the apple tree, such as comfrey, chicory or horseradish, they will not compete with the apple tree for the same soil moisture.  If you are considering placing another tree next to the apple tree, consider a tree with a deep tap root that draws up moisture from a different soil depth than the apple, such as a walnut or hickory.

Choose the right plant for the right place

This is one of the advantages of growing native plants.  Native plants are adapted to thrive in our area, although finding a niche in your yard that meets their specific needs is important even for native plants.  Sometimes this is the toughest for me because plant preferences are often general and it isn’t always easy to apply general information to a specific place in my backyard.  The best help for this, I think, is observing what does grow successfully in a particular area, accumulating experience with successes and failures, and having the willingness to move or remove a plant if I initially chose the wrong place.

I often say that plants in my yard have to be “tough” because I practice a mostly hands-off approach after plants are established.  If a plant does not thrive, then I either did not select the right plant for that spot or I did not set up the system to make sure the ecosystem provided for its needs.  As an example, I have planted elderberry bushes at all levels of the slope and the ones that thrive best have some shade and are lower on the slope and closer to the water table.  However, if I plant them too far from the house, they are heavily browsed by deer and the berries are eaten by birds, so I try to find a balance between the plants’ water needs and my desire for a harvest.

Shape the physical landscape to catch water and direct it to where it is needed

In addition to the practices above, on a limited basis, I have tried to sculpt the land to catch and slow water so that it sinks into the ground.  A large section of my backyard is sloped with a southern exposure.  This makes it a wonderful place to plant early in the spring because the soil warms and dries first; however, in a hot, dry spell, the slope can bring too much heat and evaporation. In some places, I have created terraces to reduce the slope and slow rain runoff.  In other places, I have built small swales on contour to capture rainfall and let it slowly sink into the soil. In the places below the swales, my plants tend to remain green long after plants planted without a swale.  Swales can also direct water.  If you get significant water running off from your roof, driveway or other impermeable surface for example, you can use a swale to channel it where you want the water to go.  You can also dig ponds to hold water, but that is a more major undertaking and I have only dreamed about adding a pond so far.

              Here is a photo of part of my hedgerow.  It is located on the southern slope, with
                full exposure to the sun, and is too far for my hose to reach for any irrigation.

                      This is an area where I used all the techniques I describe in my essay:  the    
                       high organic matter in the soil, no tillage or foot traffic, layers of mulch,
                          drought tolerant perennials, and shallow swales to capture runoff. 
                     If you look at the grass, where none of these techniques have been used,
                               it is quite dry and crunchy; the hedgerow is still green and
                                                      perennials are blooming.

As I was wrapping up this article, we had a brief summer rainstorm.  It only lasted five minutes, but every little bit helps.

Additional Resources:

If you want to read more about gardening with nature or any of the techniques I talked about today, Gaia’s Garden: A Guide to Home-Scale Permaculture by Toby Hemenway is an excellent resource and our library has a copy.

If you are interested in building and protecting healthy soil, the University of Maine Cooperative Extension has an informative page on Soil and Plant Nutrition HERE.