Spring 2022 Conservationist

Planting for Small Spaces

by Jenny Kamm, Community Engagement Services


As someone who loves to plant flowers and grasses but has little backyard space, I’ve learned to become a fan of container gardening. It might seem that these constraints would rule out enjoying the benefits of native perennials, but it’s quite the contrary.
Native plants are one of the best things for any garden, even one in a container. They require fewer herbicides and pesticides than nonnatives, making them easier to maintain. They’re cost-effective, too, because they return year after year, a fact that offsets any extra investments made up front. Aesthetically, they create a beautiful homage to the bountiful prairie lands that once dominated this region.

When considering this type of garden, the container is the most important part. Fortunately, you don’t have to break the bank or reinvent the wheel to find the right one; you just need to keep two things in mind. First, any pot you use should have drainage holes, be deep enough for long native roots, and be wide enough for growth. If a pot’s deep and wide enough but lacks drainage holes, simply add a few yourself. You can also promote healthy drainage by placing rocks at the bottom so the roots don’t get soggy in standing water.

Second, give thought to the material of the container, especially if you plan on moving it. Wood or porous clay pots can be attractive, but metal or plastic ones are usually more durable and weigh much less. To further reduce weight you can displace some of the soil with artificial fillers, such as cut-up pool noodles or empty water bottles. Fill the bottom quarter of your container with these items and then lay a sheet of landscaping cloth on top before adding the soil. And don’t be afraid to get creative. Last spring I turned a 30-year-old wheelbarrow into a bed for shallow natives!

Selecting what soils or other elements you’ll use to fill your pot is next. Check your plant label for soil needs. Soil compacts over time so a mixture is a good option for container planting. For instance, if a plant requires sandy soil, add coarse builder’s sand into the mix. In any case, avoid peat; it breaks down into carbon dioxide and water, not ideal conditions for plants.

And a word about fertilizer. Fertilizers aren’t always necessary with native plants but can be helpful if natives are mixed in with annuals. Too much fertilizer, though, can kill a plant.

When it’s time to water, you don’t need a set schedule. Rain will take care of a lot of your needs, but plants do lose moisture on windy or hot days. To check the moisture level, stick a finger about 2 inches into the soil. If it’s dry, you may need to water, but make sure you water the container thoroughly so all the plants get an even amount. For the best outcome, combine plants that like similar moisture levels. If you notice the leaves begin to droop or yellow, it’s a sign the roots may be rotting and you’re likely overwatering.

When it’s time to start selecting plants, you’ll need to assess how much light your garden will receive. Fortunately, an inexpensive light meter can help. As with moisture, it’s best to calculate how much sun a spot will receive and then use plants with similar light requirements.

You’ll also need to plan around the height and spread of plants when they’re mature. After all, it takes about three years for plants to reach their maximum size. In addition to envisioning how plants will fill in, don’t forget vertical growth. In some cases you may want to consider investing in a trellis or lattice to support taller individuals.
One way to select natives is to use the matrix planting technique: Plant a sprawling ground cover, and pepper in some taller plants to add dimension. At the center or “back” of the pot, bunch in some native grasses to add texture and height.

Another planting technique is to incorporate a “spiller,” a “filler,” and a “thriller.” Low-growing spillers drape over the side of the pot. River oats is an attractive spiller because its seedpods bow down in delicate arches. Fillers take up the space between spillers and thrillers. They’re low to medium growers that form nice clusters of vegetation. Wild geranium is an effective filler because it has attractive foliage as well as soft blossoms.

Finally, thrillers are the exclamation points or statement pieces. Wild bergamot is a thriller with tall stalks and bright blooms. (Its leaves also have a pleasing basil scent.) Thrillers can stand alone, but they really shine when accompanied by fillers and spillers.

Regardless of which design technique you use, pay attention to plants’ bloom times. Try to stagger them so you have color year-round, even if it’s simply brown or red woody vegetation in winter. When winter arrives, though, you may want to bring plants indoors to prolong the life of your container. Deadheading flowers in February can also help.
There are many options for growing natives no matter the size of the space. Whatever container you choose, if you use native plants you’ll not only enjoy a diverse array of colors and textures but also provide islands of habitat for local wildlife. So let’s get planting!