Plants That Prove Their Mettle

Last week I began to offer some pointers on how to find the best plants for your gardens and landscape based on trials that have proven to be reliable and unbiased. This week I continue with more on my trials that have been going on for nearly 10 years. Not fully scientific, not totally unbiased, but for the most part ... reliable.First, the echinaceas—once upon a time simply referred to as purple coneflowers. Now, each year eager breeders seem to bring a few more introductions to the marketplace. They’re not all good, and they are getting ridiculously expensive.

Want a reliable and inexpensive old-fashioned coneflower? Look for “Magnus.” It has vibrant, traditional purple color and without getting aggressive it easily naturalizes. The habits of the newer coneflowers are far from the vigorous purple cone flowers of earlier years that came only in purple, but one has really caught my attention ... Hot Papaya.

Bred in Holland, these plants flower at about 15 to 18 inches in an interesting red-orange color. Deer, rabbits and groundhogs seem to adore them, so be careful, and I found that they do much better in full sun than with just the slightest bit of shade, which causes them to flop.

Don’t expect the usual coneflower type of flower, either. There is a large raised center button with the flower rays drooping slightly well below the button reaching down and outward. The color, though, is striking and unusual. If you’re planning on a mass planting of Hot Papaya, start saving up. In July, I saw these for 20 bucks, even on sale.

You may be familiar with the dwarf variety of purple coneflower called Kim’s Knee High, which has been a popular purple coneflower for the front of the perennial border. But for the past two years we’ve been trialing Echinacea “Mistral,” which is a sport (a branch or stem of a plant that is different from its parent) from Kim’s, and it’s done very well. Producing up to 80 flowers per plant in the second year, it’s not only prolific, but the flowers and color are very stable, with reliable color, great branching habit and great cold-hardiness. This plant also got outstanding reviews as a top performer in the Colorado State University trials a few years ago.

If you’re looking for a plant that does well in moderate shade to partial sun, then I can also recommend the astilbe “Visions” series, which comes from the chinensis (or Chinese) species. The one that I think is most striking in flower color is the original “Vision,” which has a raspberry color that seems to brilliantly stand out in some shade. With flower spikes from 12 to 15 inches, the “plume” is at least twice as dense as on other astilbes, making it much more noticeable and also great for cuts. You may also find that this new astilbe group flowers longer than other varieties. There are colors in the “Vision” series including pink and white, but if you want the raspberry color it’s simply called “Visions.” Another thing to remember is that the chinensis astilbes are more drought-tolerant than other species and less prone to wilt and “crisp” when we have dry spells.

There’s also a new series of bedding mums that you should look out for. They are called the Igloo series and were developed by Blooms in England. When first introduced, they were botanically chrysanthemums, then moved to dendrathema, but now they have once again been moved back to chrysanthemum. It’s called botanical whiplash. I’ve had them in trials for about six years and they have some characteristics that make them great bedding and landscape mums. They are self-mounding and need no shearing or pinching, especially when used as mass plantings as opposed to individual plants here and there. Each plant grows about 18 inches tall and 2 feet wide. When planted on 15-inch centers, they can form a line, shape or short hedgerow.

They are available in raspberry (Cool Igloo), white (Frosty Igloo), yellow (Sunny Igloo), coral red (Rosy Igloo) and orange bronze (Warm Igloo). After several years, Warm seems the most compact, followed by Rosy, with Frosty being the tallest. This year we started trials on Sizzling Igloo, which is a yellow daisy-type flower, and Icicle, which is a white daisy-type with a yellow button. These two should start to show up in garden centers and in catalogs next year.

One of the things that I noticed in this mum is that in some growing conditions it is a double bloomer. We noticed this first with Warm Igloo, when for two years in a row it flowered in July and then again in early autumn. We’ve seen the same in Frosty and Rosy, though they seem to flower about two weeks later. I discussed this with the American distributor of the plants and they said they had gotten similar reports from other parts of the country. The plant seems to have a habit of flowering twice in the same year, although in the initial year it may flower only once. They are also among the hardiest of bedding mums, with no issues down to zone 5.

When the perennial geranium Rozanne was introduced nearly a decade ago it immediately became a hit among gardeners. The flowers were bright, the blooming period stretched through the summer and into fall, the habit was controlled but spreading and it was reliably hardy. Rozanne proved unique among perennial geraniums that had a previous reputation for being unreliable or even sloppy. Well, there’s a new geranium on the block.

Geranium Azure Rush was discovered in Germany and is a sport of Rozanne, so we know it’s got great lineage. As described by the breeder: “As where Rozanne rambles Azure Rush ambles,” and it’s a bit shorter, neater and lower-growing than Rozanne. Actually, I’ve been amazed how in just a year one of our trial plants has grown from a 2-inch plant to where it now covers a space 3 feet long and 2 feet wide. Flowering begins in mid May and continues until frost, and it can be planted in sun to light shade. This could make an interesting groundcover with tall lilies popping through the plants and flowering several feet above.

Lastly, the hydrangeas. I’ve been trialing hydrangea macrophylla “Fantasia” upstate since 2011. This hydrangea is a type that blooms on both old and new wood and it’s very rare to get any hydrangeas in any color other than white to bloom in my zone 5 garden. Fantasia did, so if you’re looking for a reliably hardy macrophylla with lime green and pink flowers that fade to pink with apricot-mauve tones ... this may be a winner. It’s short, though, growing only 3 to 4 feet tall and as wide. Hydrangea paniculata Bobo is new to our trials, but while only in its second year, it’s been impressive with its fast growth and prolific flowering. A dwarf growing to only 3 to 4 feet, it has white flowers that begin to turn to a light pink to rose as they mature. So far I’m impressed with the habit, prolific flowering and the plant’s color changes as the flowers mature but don’t deteriorate.

Time to get planting again, and don’t forget that it’s been pretty dry, so water all your new plants generously several times a week until frost. Keep growing.