Skip to content
Elisabeth C. Miller Library

Keyword: Echinacea

drought-tolerant container planting

Our neighborhood has a small planter area at its entrance. There is no water supply to this area, but a nearby resident is willing to water occasionally. The soil contains much clay. We would like to plant a few drought-tolerant annuals to add color and supplement the more permanent shrubs–such as boxwood–planted in the area. Can you recommend some plant choices? How could we amend the soil to best hold water during the upcoming dry months? Would a commercial product such as “Quench” be of any value, in addition to organic mulches?

I found the following article by Nikki Phipps on GardeningKnowHow.com about drought-tolerant container planting. Here is an excerpt:

“…many plants not only thrive in containers but will tolerate hot, dry conditions as well. Some of these include annuals like marigolds, zinnias, salvia, verbenas, and a variety of daisies. Numerous perennials can be used in a xeriscape container garden such as Artemisia, sedum, lavender, coreopsis, Shasta daisy, liatris, yarrow, coneflower and more. There is even room for herbs and vegetables in the xeriscape container garden. Try growing oregano, sage, rosemary, and thyme. Vegetables actually do quite well in containers, especially the dwarf or bush varieties. There are also numerous ornamental grasses and succulents that perform nicely in containers as well.”

This Brooklyn Botanic Garden’s 2001 article provides a list of drought-tolerant plants for containers.

I had not heard of Quench, but since it is cornstarch-based, it is certainly preferable to the hydrogel and polymer products which are more widely available. I found an article by garden writer Ann Lovejoy in the Seattle P-I (June 3, 2006) about Quench. Here is an excerpt:

With pots and containers, mix dry Quench into the top 12 inches of potting soil in each pot and top off with plain compost. Few roots will penetrate deeper than a foot, so it isn’t very useful down in the depths of really big pots unless you are combining shrubs and perennials.

I would not recommend hydrogels or polymers as a soil amendment. Professor Linda Chalker-Scott of Washington State University has written about these products and their potential hazards. Here is a link to a PDF.

You could consider applying a liquid fertilizer (diluted seaweed-fish emulsion would work) to your containers once every week or two during summer. Here is an excerpt on some general information on container maintenance, from a no longer available Ohio State University Extension article. Excerpt:

“Once planted, watering will be your most frequent maintenance chore, especially if you are growing plants in clay containers. On hot, sunny days small containers may need watering twice. Water completely so that water drains through the drainage hole and runs off. Water early in the day.

“If you incorporated a slow release fertilizer into the potting mix, you may not need to fertilize the rest of the season; some of these fertilizers last up to nine months. You can also use a water-soluble fertilizer and apply it according to the label directions during the season.

“Mulch can be applied over the container mix to conserve moisture and moderate summer temperatures. Apply about one inch deep.

“Depending on the plants you are growing, you will need to deadhead and prune as needed through the season. Monitor frequently for pests such as spider mites. Pests usually build up rapidly in containers.”

on intergeneric crosses

I noticed a plant called Echibeckia for sale at a neighborhood grocery—must be some kind of cross between Echinacea and Rudbeckia. Why would plant breeders do this? Are these crosses garden-worthy? Will they be as attractive to pollinators as their parent plants?

 

xEchibeckia is described as an intergeneric cross (the x represents a cross between two genera), but according to Plant Delights nursery owner Tony Avent (quoted in Greenhouse Grower, March 2015), it does not appear to differ from an ordinary Rudbeckia hirta. “‘We have to be careful with intergeneric crosses and make sure they are truly what they say they are,’ he says. ‘If we don’t, we will lose credibility with consumers, something our industry can’t afford.'”

In her book Butterfly Gardening (Princeton University Press, 2018), Jane Hurwitz mentions this very issue. This trademarked (i.e., propagation prohibited), human-made cross is said to have larger and longer-lasting flowers, faster growth, and disease resistance but it may be “less useful to butterflies and their caterpillars. […] Given the wide number of variables that altered plants introduce, it is easy to summarily dismiss garden plants that have been bred to differ from the straight species as harmful to the garden food web. However, these plants are a fact of life and are promoted by a large, thriving, retail nursery industry […] so the plant buyer should be aware of both their virtues and their shortcomings.”

If you want to grow only those plants specifically known to attract pollinators and beneficial insects, then plant species Echinaceas and Rudbeckias, or choose cultivated varieties with a known track record in attracting them. But if you have fallen in love with this plant, why deny yourself the enjoyment of its presence in the garden? An informal survey of Pacific Northwest gardeners suggests that Echibeckia may do best in containers that are regularly watered and fertilized. Several gardeners found them to be short-lived (more like annuals than perennials), and susceptible to mildew at the end of a long season of blooming. Your experience may differ. Experimentation leads to discovery: it may do well for you, but if Echibeckia fails to thrive or attract as many pollinators as you might wish, there are always other plants to grow.