As a landscape designer I often think about how gardens look. I’ve written articles in this newspaper about how to make gardens look good all year. Clients ask for help improving the appearance of their gardens. We want our outdoor spaces, like our indoor spaces, to be pleasing to the eye. We want our gardens to be colorful, rich in texture and lush. Looks are important to us.

But the longer I tend my own garden, I learn how much more there is to it than meets the eye. For no matter how small or how recently planted, all gardens are part of the larger ecological landscape. They provide habitat for insects, birds, spiders, butterflies, frogs, worms and a host of (dare I say?) beneficial fungi that live in the soil. Capitol Hill gardens filter and cleanse rainwater before returning it to the Anacostia River and then the Chesapeake Bay. In short, no matter how our gardens look, it’s what they do that matters most.

The good news is that your garden can be visually alluring and ecologically beneficent if you expand your awareness to include the soil, water and even the air flowing around it, and reconsider which plants you introduce. When selecting trees, favor those indigenous to our mid-Atlantic region because they provide habitat to an overwhelmingly greater number of native butterflies and other pollinators than non-natives and thus are a critical part of our larger food web.

So if you have the opportunity to remove a Bradford Pear that’s destined for the mulch pile anyway, do it! Replace it with a flowering native tree like serviceberry (Amelanchier grandiflora), fringetree (Chionanthus virginicus), dogwood (Cornus florida or Cornus mas), Carolina silverbell (Halesia carolina), crabapple (Malus ‘Donald Wyman’), sourwood (Oxydendron arboretum), or witch hazel (Hamamelis intermedia). And if you have room for something larger, remember the mighty oak (Quercus alba or Quercus palustris), maple (Acer rubrum or Acer saccharum) or river birch (Betula nigra).

According to entomologist Doug Tallamy, author of “Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens” (2007 Timber Press), “… a land without insects is a land without most higher forms of life.” Tallamy reminds us that people are included in this statement, because, “the oxygen in each breath we take has been produced exclusively by plants.” That bug or caterpillar in your yard may be one of the good guys. You can easily check in “The Organic Gardener’s Handbook of Natural Insect and Disease Control” by Rodale Press. Remember, some insects eat hundreds of mosquitoes and thousands of aphids each day.

Tallamy’s research shows that biodiversity was markedly greater when native plants were favored over non-natives in residential landscapes. Does this mean you should rip out your rhododendron or your prized Japanese tree peony? Not at all. But be aware that the larger the plant, the greater its potential impact on biodiversity. Your tree selection can do a lot more good than your perennial preferences, though both do matter.

Living in Washington, we are so accustomed to complex political problems with intricate policy implications that it may seem simplistic to say that planting a tree can solve anything. With extensive habitat fragmentation and rampant landscape disturbance it may seem naïve to imply that recreating ecological connectivity, structural heterogeneity and resilience can be accomplished one backyard at a time. But this is exactly what Tallamy’s research suggests. We literally have the ability to knit our damaged landscape back together with our collective individual actions. That’s good news.

So what about the soil, water and air? Simply put, plants have better immunity when they’re not stressed. They want to grow in porous soil rich in organic matter; evenly moist without extremes of drought and flooding, and with adequate light and air circulation. Try some of these techniques and see how your plants respond:

Some Hill residents help keep their soil moist by using rain barrels. The best looking and least intrusive I’ve seen are by Arid Solutions (www.aridsolutionsinc.com ). Add a product called Soil Moist (www.soilmoist.com) to the root zone of your potted and in-ground plants. These tiny synthetic polymer crystals store moisture and release it into the soil as it dries. An added bonus is that they aerate the soil as they work. Some Hill residents have installed green roofs on their porches and storage sheds, reducing storm water runoff into our overburdened sewer system and wisely using it to sustain rooftop plants that reduce overheating of the structures below. Grants from the DC Department of Environment are available for individual green roof projects through DC Greenworks (http://web.mac.com/trees14/Site/About__Green_Roofs.html).

Garden fungi need more respect. Actually, mycorrhizal fungi have a symbiotic relationship with plants’ root systems and protect them from disease, encourage root growth and greatly augment their water and nutrient gathering abilities. See famed mycologist Paul Stametzs’ website for more, and try some of his “myco grow” products in your own garden (http://fungi.com/mycogrow/index.html).

Finally, there’s plenty of time to make the June 15 deadline for Casey Trees Request for Planting Program, which provides trees, tools and technical assistance to homeowners (www.caseytrees.org/programs/program_docs/RFPPhaseAppl2007-08.pdf).

Happy spring, and happy gardening!