Gardening is a practice dense with quality of life benefits. For apartment residents, gardening may be pruned to a single plant that thrives without direct sunlight, without much care at all. And yes, there are plants for that. Gardening on more traditional scales—from patio containers to vegetable beds to home landscapes or a small orchard—draws the gardener to wrestle with ecological impact considerations. In overview, here are a few.
Grow some of your own food.
Self-evident, right? Being fresher and often tastier, food grown at home can contribute to a healthier and happier gardener, and because food grown at home doesn't come with the carbon footprint of commercially produced and distributed foods, it is also a personal contribution to a healthier world.
Herbs like thyme, oregano, and chives need little space, a sunny windowsill may do.
Radishes are a gardeners 'instant gratification' while Brussels sprouts need more space and more time than other vegetables. Most vegetables will fall within that "long and short of it." Homegrown tomatoes are legendarily meaty and delicious.
Try companion planting. Dill, parsley, and fennel will invite the "good guy" predatory insects you will want in your garden, lacewings and lady beetles. Garlic and onions are repellent to many pests. Become informed, choose wisely, then get your hands dirty.
Learn about soil health.
In many areas, "amending" soils may be more harmful than simply respecting the fact that nature itself may have built soil more easily damaged than improved. Learn something of mycorrhizae and other organism networks by which nature continually "amends" many soils. Nature herself builds biologically rich soils simply through the decomposition of ongoing leaf litter. Learning from nature's models you may discover that your soils benefit more from periodic surface applications of compost and mulch, than from tilling.
If you intend to grow something that cannot succeed in your humus-poor, nutrient-poor soil, or in heavy clay, consider growing something more suited to that soil, although options will be fewer. If that just won't work for you, tilled amendments may become necessary. If so, do a bit of homework before purchasing amendment products.
Don’t be addicted to lawns.
The Middle English word launde referenced an opening in the woods. With the expansion of human population and timber harvesting, Europe came to be denuded of its primeval forests, and such 'openings' became increasingly typical of the English landscape. As an expanding landowner caste took command of the land, the uniform expanse of manicured, monocultural turf grass became a statement of material success. A private park, a large piece of land that wasn't needed for timber or for agriculture, but was instead a socio-economic statement to be gazed upon with admiration, perhaps jealousy. Important people had lawns. While the English climate does lend itself to such a fashion, the reliably green lawns were never green in our present ecological sense. Monocultures displacing long-adapted and much richer biota is a certain engine for species loss. But the emerging lawn culture of 17th century England wasn't as destructive as the lawn culture came to be in 20th century North America.
The lawn addiction is an environmental problem, especially so in climates less suited to lawns than the Europe of ages past. So look into replacing lawn with a garden 'meadow,' including at least some native plants in a more visually interesting variation of heights, colors, and textures.
If you're not intent on advertising your position within the gentry, maybe you don't really need all that turfgrass.
Plant native plants. Remove invasive plants.
Our planet, the only planet known to be a host for biology, is experiencing what some scientists have called the sixth great extinction. It is inescapable that the greatest driver of species loss is human activity. This has been true for a long time. Note that so-called stone age human hunters are believed to have driven the extinction of the woolly mammoth, and likely a large number of species of less fascination to present humans. Seven and a half billion industrialized humans easily do a great deal more damage than, say, <30 million stone age humans could! In many urban settings it is now possible to travel block after block without seeing any plants native to that place. Over long time spans, native plants co-evolved with myriad other organisms, large and small, organisms in many cases dependent on the plants they have long adapted alongside. The loss of native plants inevitably drives the depletion of specialized soil organisms, the loss of plants integral to insect life, including insect reproduction, promotes the loss of native insectivorous birds, frogs… you get the picture. Historically, a problematic issue has been human migration itself, we introduce non-native plants that, without the natural controls of their places of origin, easily displace native plants. Remove enough blocks from a wall, and that wall is in trouble.
No matter where you live, many wonderful native plants can be smart selections for your gardens and landscapes. Get to know the local nurseries that provide native plants (likely this will not include those big box stores).
Begin going native. Bring nature home.
Learn the basic principles of IPM.
If you enjoy gardening, but are not familiar with the principles of IPM, Integrated Pest Management, this will be a good time to enter that world. The specifics of how to most responsibly grapple with each weed and each varmint are too extensive to list, but the core principle is common sense ecological stewardship. If possible, prevent or minimize the problem. If that does not work out, identify your pest and determine your action threshold. How much of a response does the problem warrant? Don't use controls more damaging than needed. If bluebirds are taking less than 5% of your blueberries, is it really worth busting out a shotgun? If you've got six Russian thistles, pull them out rather than reaching for six gallons of glyphosate. If your flyswatter missed a fruit fly, please don't acquire a surface to air missile! The principle is a modest modification of Hippocratic thinking. How effective is effective enough while avoiding significant harm?
Without passing judgement from afar, there may be situations where a heavier hand is warranted. Try to avoid that place.
Plant a tree.
While small gardens may not accommodate an added tree, many gardens cannot be their best without appropriately selected and located trees. Everyone knows something of the plant magic we call photosynthesis (literally, "making stuff with light"). Chlorophyll absorbs light and the energy of photons disassembles certain molecules, the carbon and hydrogen atoms re-manufactured as a simple food, sucrose, with the 'leftover' oxygen atoms, the byproduct oxygen, released through the plant's stomata. Carbon is 'scrubbed' from the air and we get what makes breathing possible. It's a natural magic without which animal life, humanity included, cannot exist. Whether he knows it or not, "man's best friend" is green. While all plants work this life-enabling magic, and while the planet's most critical photosynthesizers are the great masses of microscopic oceanic plants (phytoplankton), the durability and scale of trees make them photosynthesis rock stars. Of course, they're often aesthetic rock stars as well.
There's more to be said about the significance of trees— soil building, soil conservation, habitat and food for wildlife, heat mitigation, carbon sequestration. Through a narrower anthropic lens: fruits, nuts, materials for homes, furnishings, rayon textiles, and more. Trees enable our breathing, furnish our lives, we literally wear them.
Again, do some homework before selecting and planting a tree. Select one that has similar water needs to nearby plants, think about surface roots, about not shading vegetable bed areas that will need direct sunlight. Give special consideration to native trees (see reasons discussed above and below). If selecting for fruit or nut trees, do some homework on what to expect at harvest, what is involved in harvest, and what to expect regarding the pests that will be attracted.
Our crowding world is running low on trees. Be nice to our world. Plant a tree.
As the human population expands, most notably in urban areas, necessary resources face increasing strain, and nothing is more necessary than water. Humans further accelerate this inevitable water-drain by contributing to climate change, by wasteful habits, by drawing down subterranean aquifers, by disrupting watersheds, and by outdated agricultural and gardening practices. Residents of dry, low-precipitation areas, do have excellent options for gardens that work naturally in those areas. Desert properties do not need lawns!
Consider installing a bioswale to retain more rainfall in your soil, creating an interesting landscape feature in the process. Consider rain barrels. Consider greywater systems. Look into permeable hardscape features, including driveways and walkways.
Irrigation technologies have made fantastic advances in recent years. Inexpensive smart controllers have advanced far beyond being merely programable, they can 'know' when to water your garden and when not to. Humans can be smart too, an attuned gardener will come to know when and where water is needed. This gardener knows an outstanding gardener who suggests "the beer watering system": when a patch of garden needs water, open a pint and start hand watering, when the beer is gone, that patch of garden is watered. Although a very good gardener suggests this practice, this system is not being advised here.
Create a welcoming place for wildlife.
(Birds, pollinators, beneficial predators.) Industrial, residential, and public infrastructure developments are constantly removing natural habitat and ultimately removing beleaguered species permanently. If you're thinking about planting an exotic Ginkgo biloba tree that traces to another hemisphere, please also consider that a native oak might have important relationships with 100 times as many of your local wildlife species, including the birds and butterflies you'd like to see visiting your garden. Attractive native bunch grasses may draw finches. Asclepias will attract Monarch butterflies.
There are rational arguments both for and against using bird feeders so we'll not fuss about that here, informed people will disagree. But wisely selected water features, say a recirculating Zen fountain, will invite hummingbirds and finches, and it will invite the gardener and friends into the garden as well.
Set up a compost bin.
This is an obvious way to create better soils for garden beds, whether your gardening approach is "no till" or involves tilling compost into your beds.
Composting is also an obvious way to employ the 'Reduce/Reuse/Recycle' practice.
What goes into your compost bin? Noting that there are exceptions, almost anything vegetable; virtually nothing animal. The simple rule of thumb: vegetable—yes, animal—no. No meat, no dairy, and absolutely no pet waste. While certain specific animal waste may be "hot" composted, think cattle, poultry, the bat guano that nature hot composts as deep deposits on cave floors, it's highly unlikely the home gardener will be hot composting, so it's smart to stay away from all poop. That shouldn't be difficult, right?
What does belong in your compost bin? Yard clippings, unused greens from the kitchen, coffee grounds, citrus rinds, leaf fall (if you must rake it), cut up plain cardboard, not the hard-surfaced stuff used for packaging and not any packing tape or staples. If making sure your cardboard is clean enough and if making sure it's cut up enough is just too much trouble, no worries, recycle that cardboard the alternative way.
Repeating a theme, do a little homework when starting to compost. Hot composting requires more volume and care than cold composting, so the home gardener is safe in learning only the techniques for cold composting.
Try not to use fossil fuel-powered tools.
(Mowers, tillers, hedge trimmers, etc.) Landscape maintenance and tree services may require petroleum-powered tools, but with few exceptions, the home garden does not. Improved battery technologies continue to provide the home gardener with 'greener' tools than what used to be available. If your garden work demands multiple power tools, purchase ones that use the same rechargeable batteries.
— Wes Janssen, MG
Master Gardeners is a public resource program organized by state in the US and organized by province in Canada. Typically associated with the extension programs of public universities, Master Gardeners provides gardening information, including information specific to individual states or provinces. Information for your area is easily accessed by typing "Master Gardeners" in your search engine.