Perennial Plant Recommendations

This week, a few of the plants that are in my garden that I’d highly recommend. Some have been in my garden for years and some not, but all have attributes that will add beauty and ease to your gardens. A disclaimer though, they are all perennials. After all, perennials are my obsession.

My first selection, Crocosmia, has its roots and lineage in South Africa. There are several varieties being offered, and if you had planted any of them 25 years ago you would have found that none were hardy or reliably hardy out here. This no longer seems to be the case. Once grown widely in France as “montbretias,” they began to show up in catalogs here in the early 1980s.

Not true herbaceous perennials, these plants grow from small corms but the swordlike green foliage dies to the ground every fall. Most of the corms that I’ve planted in the past 10 years have resulted in plants that have survived the winters. Varieties like “Lucifer” are said to be one of the hardiest, and its arching flower spikes have a tropical look.

Not only are they great garden flowers but they also make spectacular cuts. The corms, some as small as a quarter, are planted in the fall, and depending on the variety, flowering can begin in mid-July and last through the summer. One thing about Lucifer is that the flowers can be a bit off-red with hints of orange. For a true red I like “Diablo,” which is flowering in my garden for the first time this year. Diablo seems to be a true red with flower spikes 3 to 4 feet tall though arching.

Varieties I’m trying are Emberglow, Alborado, Diablo and George Davidson. As a whole they prefer a hot and dry location in full sun. The corms are planted 3 to 4 inches deep, and the only insect issue is the twospotted spider mite, which can show up when it’s hot and dry. The mites can be washed off with sprays of water or washed with soapy water. Every few years the corms can be lifted at the end of the season. Then you can choose the larger corms to replant. The larger corms produce the larger plants.

Fertilizer can be in the form of a granular organic applied early in the season, and one application may suffice. If you have surplus corms you can share them with friends or store them in a cold basement or garage for spring planting, but do plant your main crop in the fall. The best corms may be up to an inch in diameter, but most will be quarter size. You can cull your corms and only replant the largest ones for the largest plants.

My next selection is the red-hot poker, or Kniphofia (once called Tritoma). Over the years it’s gone by the name poker lily, torch lily and poker plant. At one point only the red varieties were available. Now you can buy them in various colors, but the reds and bicolors seem to do best. This is another plant that has its origins in Africa. Twenty-five years ago they were considered to be marginally hardy, but now virtually all the varieties will overwinter.

Like the Crocosmias, the Kniphofias have sword-like foliage, but the leaves are narrower and more pointed and not as long. In July and August they send up spikes of single or bicolored flowers similar in shape to a grape hyacinth flower sans the scent. The plants can be massed for effect with five to 10 spikes from each crown depending on the age of the crown. I’ve found the odd colors like the yellows and greens to be less hardy than the reds and red/yellow bicolors.

So far in 10 years of growing them I’ve found no insect or disease problems. This plant also likes a very sunny disposition in a well-draining soil. Put them in a spot that’s irrigated, and they will languish. Hot and dry is their mantra. And yes, they also make nice cuts. I’ve grown Azure Rush, Elvira, Lady Luck and Joker’s Wild. Joker’s Wild is my current favorite with the flowers topping out at just over 3 feet in a dark orange with 4 to 5 inches of color that can be deep orange at the top of the flower with hints of yellow toward the wider bottom. The plants can be divided in their third or fourth year, in the late summer or early spring using a sharp knife to split the crowns, which are then replanted.

Tall garden phlox (Phlox paniculata) have always been a favorite of mine because of the color range and light fragrance. They make spectacular cuts. On the downside, they do have their issues. Many varieties are prone to get mildew on their leaves in our humid summers. However, there are mildew-resistant varieties that should be on the top of your list, and you can find these on lists from the Chicago Botanic Garden and the Mt. Cuba Center in Delaware.

There are the standard varieties like Dodo Hanbury Forbes for a pink and “David” for a white, which is also fairly mildew resistant. I have not found a good red, orange or blue, though you will see them advertised. My favorite, however, is a striking violet/magenta named Nicky. It’s fairly mildew resistant, lightly scented and the flowers have an iridescent glow at dusk.

All the P. paniculatas should be grown in full sun in good soils. They won’t do well with overhead watering and may need feeding three times during the growing season. They are easily divided with a sharp spade early in the spring or early in the fall, and if you want dozens and dozens of babies just push a bulb planter into the crown in November, and you’ll end up with tons of diggable shoots in the spring.

As noted, twospotted spider mites can be a big problem if you allow them to become established. And irrigation over the top will result in mildew on even the most resistant varieties. If you’re after cuts be careful with the newer varieties, which I see as novelties, because they tend to have short stems on short plants. Kind of defeats the purpose of tall garden phlox?

Ligularias are my next selection. Most gardeners are only familiar with Ligularia stenocephala “Little Rocket,” which has green foliage and yellow flowers in spikes like a moth mullein but shorter. But there are other Ligularias that are spectacular for their foliage and flowers. The foliage can be rounded, serrated, deeply cut or smooth with colors ranging from green to deep bronze. The flowers yellow and spiked or on tall stems with orange/yellow, daisy-like flowers. The range of flowers and foliage types is pretty amazing, and I have about a dozen varieties planted in the garden’s Ligularia section.

The most common varieties are available in local garden centers, but for a larger collection try Plant Delights. Look for varieties like Osiris Café Noir, Desdemona, Hey Mrs. Wilson, Frosted Flecks and Chinese Dragon.

Flowering takes place in July and into August, and the only issue I have with any of the varieties is slugs and snails. Treat the soil at the base of the plants with a slug bait, and that will give you good control. I haven’t had a hardiness issue with any of the varieties listed.

Spigelia is a plant native to our southern states, but two varieties have been used in gardens up here. The first was “Little Red Head” followed by “Ragin Cajun,” but after their introduction we found neither to be reliably hardy. When we replaced it with the species Spigelia mirlandica, which is taller and not as compact, we found that the species was hardly even in zone 5. The tubular red flower spikes with yellow in the throat makes a spectacular display in June and into early July. If the plants are cut back after the initial flowering most will reflower again later in the summer. This is a great plant for mid-border and should be planted in groups of three for the greatest effect.

I’ve tried dozens of types of Shasta daisies over the years and have found that most of the dwarfs and semi-dwarfs are not reliably hardy. However, the Shasta (Leucanthemum) named “Becky” serves several functions as well as being fully hardy.

With white 2-to-3-inch-wide flowers and typical yellow daisy discs, this tall Shasta has rigid stems with flowers occurring from 15 to 30 inches above the ground. The flowers don’t “dirty” like other white Shastas, and when cut late in the day the flower will last in a vase for days. Deadheading does result in new shoots and flowers. There are no serious insect or disease issues, but do control slugs and snails in the area.

Briefly noted are the Thalictrums. From the 8-inch-tall T. klusanum to the 8-foot-tall T. “Black Stockings” you can have quite a collection with this genus. There is the native white flowering species or the white “Nimbus” variety and a Nimbus Pink that only grows to about 3 feet tall. T. flavum grows to 4 feet tall and has clouds of yellow flowers. There is also a double-flowered variety called “Hewett’s Double,” but don’t expect this one to be reliably hardy — though it’s worth the try.

Flowering from June and through the summer these plants need dappled shade and moist, rich soil. The T. rochebrunianum variety, which is Black Stockings, can get as tall as 9 feet in flower with its clouds of wispy light purple flowers. It’s quite remarkable. It will self-seed, and if you’re lucky enough it will form a tall patch of plants that’s quite a sight in the damp shade. All are great pollinators, but let them totally dry out and the foliage will crisp and brown.

Lastly, the Trollius. This is another great plant for cuts with single and some double flowers in the group. Also another one that likes damp spots with dappled sun or early morning sun. Varieties to look for are Orange Princess, Cheddar, New Moon, Lemon Queen, Supurbus and Alabaster. Colors range from orange to near white and yellow. Golden Queen is the last to flower and finishes in mid-July with striking nearly double orange flowers atop 30-inch wiry stems.

The flowers are similar to those of the smaller buttercup (same family) and are on long wiry stems making them great for cuts. Some are short-lived perennials, but most will last for three to five years or longer.

Keep growing.