Slow Containers: Rethinking Annuals-Only Design

April 04, 2016
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Herbal Container Design by Todd Holloway
Planter design and photo courtesy Todd Holloway.

Let’s be honest. Container gardening can be one of the least sustainable and most wasteful forms of gardening. Many commercial soilless mixes are comprised of materials that take hundreds of years to replenish or are harvested using questionable methods; the compositions themselves often require gallons of water to thrive; many of us fertilize using synthetic chemicals and sprays to eradicate pests or diseases; and the plants themselves—generally speaking grown more for show than utility—are often tossed after a single season.

Add to the above the production costs of growing plants on a massive scale (more soilless mix, more water, more fertilizers, more pesticides) and the costs (environmental especially,) of transporting plants thousands of miles to garden centers or big box stores where they are again watered and fertilized and sprayed. One wonders how we container gardeners can live with ourselves. This doesn’t even begin to touch the completely unsustainable cost—human and other—of mass-producing the vessels within which we design containers.

But it doesn’t have to be that way. We can create container gardens in a more sustainable and less wasteful manner if we deconstruct the process and rethink our choices.

Be creative with the vessel

Stop yourself the next time you contemplate purchasing that shiny cobalt-blue glazed pot from Vietnam and ask if there are alternatives. The answer is yes. And the alternatives do not need to be expensive. Of course you can purchase that locally thrown, handmade, artisan pot if you are able, but if not, look around you. There are dozens of options for vessels within your own home or garage (or at the local recycling center.) Think creatively. You could repurpose a verdigris bucket from the back porch or use that old birdcage or bureau; so long as the vessel has drainage (easily accomplished through drilling), it can serve as the basis for your next container design.

Choose plants with a purpose

Annuals—grown for maximum show and one season only—are the darlings of container gardening. Yet, for all of the reasons mentioned, they are perhaps the most wasteful of plants. Their name alone betrays them; annuals are one-season wonders.

I love annuals as much as the next designer, and for those of us who cannot imagine a container planting without them, let’s reimagine the ways we use them.

  • Grow your own annuals from seeds started in late winter. Not only will you save money and resources with this locally grown alternative, you will be rewarded with more plants and the joy of cultivating and nurturing the plants you use.
  • Consider fewer annuals in a single planting. We don’t need to abandon annuals in container plantings altogether but instead begin to view them as complements to other, more sustainable or utilitarian plant choices. For example, nasturtium (supremely simple to grow from seed) is a beautiful and prolific annual. It looks lovely spilling over and weaving through almost any container arrangement, but is especially stunning when accompanying edible plants such as tomatoes grown in pots. And nasturtium is itself edible.
  • Plant edibles. Edible plants are as colorful and striking in a planter as any annual or perennial. Swiss chard, kale, beets, and tat soi, for example, have wonderful foliage texture and colors, making them a perfect backdrop or stand-alone container plant. Patio tomatoes and dwarf blueberries are prolific producers of fruit. Herbs are delightful in cooking and cocktails. And beans or peas clinging to a decorative trellis add as much romance to a planter as any morning glory. Use edibles alone or in combination with other plants to add excitement and utility to your designs.
  • Remember the birds and bees. Speaking of utilitarian, a pollinator-friendly annual in a container placed strategically within a vegetable garden not only looks beautiful, but bees that visit it will pollinate neighboring edibles, strengthening the crop. Do your research, however; not all annuals attract pollinators equally. To be especially friendly to the environment, consider native annuals as pollinators.
  • Begin with perennials, trees, and shrubs. Perennials, including trees and shrubs, are as satisfying in a container planting as they are in the garden. They return year after year; they provide multiple seasons of interest; and they form a strong backdrop against which to add an annual or two. Add to this the reduced stress of not having to design anew every year or with each changing season, and it’s a wonder we don’t all begin with perennials in containers.
  • Incorporate plants that are easily wintered over. I can think of no better container plant for a sunny spot than dahlias. Dahlias satisfy everything I love about designing containers: there are nearly limitless varieties, shapes, sizes, and colors from which to choose; they are prolific bloomers; they are relatively easy care; and successfully overwintering them increases the number of plants with which you have to garden. Tropical plants can also be overwintered with relative ease. Although the initial investment might be costly, reusing a tropical plant yearly more than pays for itself. Plants we typically use as houseplants are also great candidates for container design—think of begonias, coleus, sanserveria, succulents . . . the list is nearly endless. If you live in a cool climate, you can bring these plants indoors during winter and out again next season.

Evaluate soilless mixes

Peat moss is the base for most commercial soilless mixes, however it is a controversial ingredient. Some are concerned that peat-harvesting methods harm the natural environment; others do not believe the amount of time it takes for peat to replenish itself is sustainable. However, peat forms the base of most mixes—including homemade mixes—because it decomposes slowly, holds a large amount of water, and lightens a mix. That said, there are alternatives to peat that are less environmentally taxing. Coir, a by-product of the coconut-fiber industry is one; aged bark, wine waste, and vermicompost are others. Consider making your own mix using one of these alternatives; a call to the folks at your local university extension office or a search online will yield options that are best for the plants you wish to grow.

Eliminate synthetic fertilizer and pesticide use

Rethinking the use of a peat-based soilless mix and replacing peat with coir, vermicompost, or organic compost serves a second function; the alternatives contain material that benefit plant growth and development, reducing the need for synthetic fertilizer. Indeed, coconut coir has been shown to facilitate growth of beneficial fungi and increase root development, and the hormones and humic acid from vermicompost increases plant growth.* Organic fertilizers such as manure tea condition a soilless mix while providing nutrients to the plants, and fish emulsion naturally provide nutrients container plants need to thrive.

Pests and diseases can wreak havoc on container plantings, as the environment within which the plants grow is often tight both because of the constraints of the vessel itself and—let’s face it—the number of plants many of us cram into a container. We know from Gardening 101 that air circulation is important to prevent diseases. The same is true for container plantings. Pests and fungi thrive in cramped quarters. To start, grow or purchase disease-resistant plants. If—after ensuring you have grown or purchased the strongest plants—you still find your container is tainted with insects or disease, try a homemade or organic insecticidal remedy. Herbal soaps, tinctures, and sprays abound. Again, a call to your extension office or online search will reveal which natural ingredients are most effective for the type of pest or disease you have.

Following any one of the above alternatives to wasteful container design practices is bound to lead to a more satisfying arrangement on many levels—environmental as well as aesthetic. Indeed there is no reason to sacrifice beauty in order to design sustainably. In fact, the possibility for increasing your design acumen grows with your container plantings.

*See Beat peat with these alternative amendments by Linda Chalker-Scott, Fine Gardening magazine issue #157.

Article from Edible New Hampshire at
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