Here are five key practices used by organic/ecological landscape gardeners. These methods result in healthy, pest-free plants and provide a rich habitat for a variety of pollinating insects, birds and other creatures.
Natural ecosystems have soil that is biologically alive. Pollution, construction and chemical fertilizers work against fostering soil life.
Think about how a healthy forest functions: Every year an abundance of leaves, herbs, woody branches, trees and dead fauna fall to the forest floor and begin the process of decay, aided by millions of soil microorganisms which make the resulting nutrients and minerals in the soil available to plants. Above ground, living plants produce their own energy through photosynthesis, the magical process of taking sunlight, CO2 from the atmosphere, and water from the soil and converting it to woody or herbaceous vegetation.
To mimic natural systems in your garden, use composts and organic mulches to increase the diversity of microorganisms in the soil. Composted leaves, straw, rotted bark, and kitchen and yard trimmings are excellent mulches that build microbial life.
If you raked your yard clean of leaves last fall and removed this organic material, you will need to replace it. Set up a composting system to help you manage all the pruned vegetation you generate over the growing season and turn it into valuable compost. If you live in a city and use a municipal composting service, make sure that you get back in compost what you sent off as yard waste. Otherwise, you are just exporting a valuable resource.
Spring and fall are great times to add a layer of compost or organic mulch 1-2” deep to planting beds. This imitates the annual forest leaf fall and provides established plants with all the nutrients they need. If you are putting new plants in compacted soil, you can dig in extra compost and organic soil amendments to increase the biological activity in the soil. In autumn, allow fallen leaves to decompose in place rather than rake them away. Lawn grass and paths can be raked free of leaves and added to the compost bin.
Vegetable gardens require lots of extra fertility because these plants have been bred with high nutrient and water demands. They are also removed at harvest, and thus are not recycled into the nutrient system. Many traditional horticultural plants also require a high level of fertility. If you don’t have your own compost, you can buy bags of composted cow manure or use liquid seaweed/fish emulsion for the more demanding vegetables and salad crops. In Maine there are many good brands of organic compost available, such as Coast of Maine and Kenney’s Compost.
Native plants rarely need all this fuss and thrive with organic mulch as their only addition. This is what makes gardening with natives so easy and satisfying. Organic mulches also hold moisture in the soil, helping plants withstand drought.
Avoid chemical fertilizers—these man-made products can kill the soil’s microorganisms and are counterproductive to building biologically active soil. They are like junk food: they give plants a quick flush of green growth, but they do not make resilient plants and can even make the plants more attractive to pests. In addition, chemical fertilizers are fossil fuel based, and manufacturing them generates a lot of pollution.
NOTE: Beware of some commercial bark mulches. Make sure the product you buy is really bark, not shredded wood pallets or junk wood (including pressure-treated wood that has been dyed).
What do organic gardeners do about weeds?
Mulch the soil. A thick layer of organic mulch prevents a lot of weeds, as most weed seeds need light to germinate. Tilling and digging expose buried weed seeds, so avoid disturbing the soil, if possible.
Physically remove weeds. There are two tricks to killing weeds besides pulling them: 1) Pour boiling water on unwanted plants, e.g., weeds in paving. Deep-rooted species may need a few treatments. 2) Vinegar is also an effective herbicide. Put some in a spray bottle or squirt gun and spray it on the unwanted plant.
Solarize the area. This works best in large sunny areas. Cover the area with black or clear plastic weighted down along the edges. After a month or two, perennial weeds and seeds will be baked by the sun shining on the plastic. Remove the plastic, plant and mulch.
If you have a plant that is succumbing to pests, it is probably because the plant is not thriving. Perhaps it is newly planted, or in the wrong location? Wash the pests off the whole plant with the spray nozzle on a hose. Then spray liquid seaweed on the foliage. You may need to do this repeatedly.
Some garden plants are just not suited to life in Maine or in your particular location; choose something else if the plant is regularly unhealthy. This is another good reason to plant natives: they do like the climate and soils here! And remember, most insects are not pests. For example, a caterpillar is the larval stage of a butterfly or moth. Get a good field guide and figure out what it is before you think of eliminating it.
Do not succumb to the temptation to use chemical pesticides and herbicides. These chemicals are persistent in the environment and they kill more than just the pest or problem weed. It is not worth it.
There are several effective ways to make your lawn ecologically healthy and resilient.
Use a mulching mower, which returns the clippings to the soil. If you are having a lawn party and don’t want people tracking grass clippings around, you can catch them once in a while and add them too your compost pile. If your lawn is small, a hand push mower is great, and the new solar-charged electric mowers work well. Aim to phase out use of your gas-powered lawn mower—they are a major source of air and noise pollution, much worse than automobiles.
To naturally green your lawn and add diversity, include white clover seed in your grass mix. White clover is a nitrogen-fixing low herb beloved by pollinators. In Victorian times, lawns had clover. The other option is to spread a thin layer of compost on your lawn to create the microbial life in the soil that will aid in grass growth. This, along with grass clippings left in place, will give your grass all it needs and will improve its tolerance to drought.
If the soil is heavily compacted and you have lots of weeds like dandelion and plantain, poke holes in the soil with a pitchfork or with special spike aeration strap on sandals (available from Gardener’s Supply).
Consider turning a very dry and scruffy lawn into a low, dry meadow with rock phlox, blue-eyed grass, wild strawberry and pussy toes. If your lawn is shady, plant some native woodland groundcovers with pathways and open areas created with stepping-stones or other porous paving materials.
Reduce the size of your lawn and add more native habitat plantings, or manage it like a meadow and mow only occasionally. This will be a boon for wildlife.
After following the practices already listed, you will have created a tremendous amount of diversity in the soil and made your yard a nontoxic landscape.
Now it’s time to add a few native plants.
Choose plants by the site conditions—sun or shade, soil type (sandy, gravelly, clay or loam) and level of moisture. Create mini-habitats, combining plants from similar growing environments. Plants from the same habitat tend to “look” good together. This is the foundation of good ecological design.
Create new planting areas with a method called sheet mulching. Choose an area that you want to convert from lawn or weeds, and cover it with overlapping layers of brown cardboard or newspaper 5 layers thick. Next add organic mulch, such as compost, leaf mold, rotted straw, whatever you have on hand. Water heavily to soak the cardboard and organic matter. Shrubs and trees can be planted directly through this covering. Perennial plants do better if you wait a couple of months to kill the grass and weeds underneath. I prepare new areas in the fall or early spring, but it can be done any time of year. This method is so much easier than digging up lawn, and you don’t expose new weed seeds.
Start small, the joy is in getting to know these wonderful plants.
For more information see Comprehensive Plant List in Native Plants & Design on this website.