End-of-Summer Standouts: Perennials That Refuse To Quit

It’s been a tough summer for gardeners, and for the second year in a row our gardens are suffering from some serious drought. I looked at some of my woodland plantings today, and despite being watered several times in the past weeks, many are just barely hanging on.

One thing about woodland gardens is that the ground-level plants are competing with taller trees and shrubs, and the tall guys simply drain the soil nearly as quickly as I can put water down. Plants with roots near the surface like the Japanese peonies seem to suffer greatly, and their foliage wilts within 24 hours of irrigation. Some think this type of weather pattern may be the new normal.

Nonetheless, there are the hardy troopers of the garden, the late-summer bloomers, which still seem to be right on time. I have about a dozen varieties of hydrangeas on the property, and at one point or another each has shown signs of drought stress. Most hydrangeas are used to it though, and those of you living along the beach areas know well that even with copious water some hydrangeas just can’t soak it up fast enough. On hot sunny days they begin to droop only to revive in late afternoon and well into the following morning.

To their benefit, and ours, the days are getting shorter and cooler, but if it seems that the gardening season is coming to an end, think twice. It’s the shorter days and cooler nights that bring out the best in many garden plants, and there are dozens of perennials that retain their foliage and flowers well into September and October, cheating those who leave the Hamptons on Labor Day but often giving the rest of us quite a show. Here are a few of my favorites.

A stunner that I see from the kitchen window are two Ligularias. They both have large green to bronze foliage, but it’s the flower spikes that shoot up from these leaves that put on a great end-of-summer show. Ligularia “Desdemona” sends multiple stems up through the foliage to about 2 feet tall. Each stem has a single orange flower about 2 inches across. While each stem has multiple buds, only one flower opens at a time, providing blooms from August through September. In contrast, the variety “Britt-Marie Crawford” sends up 2-foot stems as well, but its smaller flowers open in clusters instead of singly. In all, there are about a dozen varieties of Ligularia that I’ve been successful with, all blooming mid to late summer.

Not far away in a small 4-square-foot wet area that I call “Lake Andy,” Lobelia cardinalis has been blooming for about a month and will continue with its tall spikes of small but radiant red flowers until mid to late September. A New York native, this plant is very easy to grow, and with its slender red spikes, it tops out at about 4 feet but with a bit of shade will grow taller. It’s a hardy perennial but easily grown from seed if you choose to take that route. It does require wet soil though, so it does best in boggy wetland areas.

I so like the diversity that you can find in the perennial geraniums. From the mounding types to the viney ones, they all have a place in the garden from the front edge to the back. Years ago I planted what I think is geranium “Johnson’s Blue” in the middle of my island border though there are other perennial geraniums that also have a similar twiney, viney habit. The stems crawl and twirl throughout the garden, blending in magnificently. Then every few inches a flower appears.

I’m not a big fan of the all-too-common rudbeckias or black-eyed Susans. But there are other interesting perennial choices in the family. I got my first Rudbeckia triloba from a guy up the street who had no idea what it was. The plant has almost palmate foliage, growing to about 4 feet, but the flowers are tiny for this family and only about an inch across. Much to my surprise, when I started growing it in my garden it grew to nearly 8 feet tall and was absolutely dense with its small yellow flowers. Late in the summer, they are visited regularly by several bird species including grosbeaks and finches that adore the seeds. The plant does self-seed though. So each spring as the new plants germinate, it’s important to thin them out quite a bit.

Growing through and into the R. triloba is Rudbeckia “Henry Eilers.” Also on the taller side, this Rudbeckia has unique flower petals that are tubular, and when allowed to grow in and through the R. triloba, it gives a wonderful contrast of flower styles and diversity within the genus.

Then there are the Phlox paniculata, or old-fashioned garden phlox. These can get fairly tall depending on the variety, and colors can range from red to pink and pure white. Some have small red to pink eyes in the center, and others with near white flowers can have lavender swirls. It’s hard to find a nice red variety, and those that do survive are on the short side. I’ve just about given up on the blues, and powdery mildew can be a huge problem on these out here. Nonetheless, they make great cuts and will bloom well into September. Most have a mild, sweet scent. Thin the stems to allow air penetration and reduce powdery mildew. (Refrain from overhead watering.) Want to keep them shorter? When the stems are about a foot tall, take off the top inch. This will keep them short, but it also will cause them to bloom later than the unpruned ones. The last bloomer and most powdery mildew resistant is the tall white variety “David.”

If it’s tall you want then go for Thalictrum aquilegiifolium. With purple flowers in airy masses atop tall stems they thrive in the mid-garden where the foliage reaches a foot or more from the stems, and the tiny flowers show up as clouds of light purple suspended in air. It’s not unusual for mine to reach 7 to 9 feet tall. They’ll take sun, but they resent baking in it. There are also yellow and white varieties, but if you want spectacular go for this species. The variety Hewitt’s Double is indeed double but not reliably hardy.

Anemone hupehensis and also japonica, or the Japanese anemone, come as several different varieties, but they tend to bloom from late August into September. With single or double flowers on stems 15 to 36 inches tall, they are reliable and carefree. Flowers can be single and open or double with an extra row of petals. Colors tend to be a pale rose to mauve and white. They are virtually carefree and one of those rare plants that once established will need little to no care. The variety Puff “Pink” is both gorgeous and unique as a compact plant but still with stems suitable for cuts.

There are also a few hostas that are late-summer bloomers, including the varieties “June” and “Invincible.” There’s a third variety that I have blooming now, but I have no record of its name or origin. I call it “Liner” as it’s lined out at a border edge.

It has 8-inch-long leaves that are ribbed from stem to tip with dense lavender flower spikes. I have it planted in a totally shaded 2-foot-wide-by-20-foot-long border outside my office where there’s bright light but no sun, and it’s perfect. It never seems to need water, flowers for about a month, and at the end of the season we just cut it to the ground. Rabbits do run to it though as a great hiding place.

There are some magnificent late-summer blooming Cimicifuga (aka Actaea) that have dark, dark foliage and bottle-brush white flowers atop tall stems. Bees love the flower spikes. My favorite is “Brunette,” and I was able to isolate a dwarf seedling that I call “Early Brunette,” which flowers several weeks earlier. But whereas Brunette can have dozens of flower spikes in each plant, my “Early” one has no commercial value since it only throws up one spike a year. It’s interesting but seems to have little garden value. Keep growing.

GARDEN NOTES

Because of the drought, leaves on deciduous trees are dropping early this year. Remember that most of these leaves belong in your compost pile and not in the garbage or dump. It’s also important not to leave them on the lawn as any rain (ha, ha) will mat them down and kill the grass underneath. It’s not too soon to do your fall lawn feeding. It used to be suggested for later in the fall but a good deal of recent research shows that too much of that fertilizer added later in the fall isn’t as effective as when applied now through mid-October. Patch seeding on the lawn can continue into October as well but when using a premade patch mix keep in mind that it probably won’t match the surrounding lawn when it comes to color and texture, but it may be close.