It’s wilting season—the time of year when days are long and temperatures are high. You can stay home and water those shrinking violets, or choose some seriously stand-up plants. This is where knowing a plant’s origin comes in handy. It stands to reason Iceland poppies won’t stay as perky as New Zealand flax in the midst of a heat wave.
Even heat lovers are vulnerable to hot, sunny days
You can’t go wrong with the typical annuals you’ll find at your local garden center. But even heat-lovers like Salvia, Lantana and Petunia will sulk in the hot sun until they settle in. Plants that are perky in the pots they came in will become sulky when replanted in the ground or in a container if the temperatures soar along with the sun.
The one-two punch of the sun-temp combo can do a number on unsuspecting plants. When days are cool and moist, even shade-lovers will tolerate some sun. And here’s where it takes me by surprise. Every year, the potted cane Begonia that was enjoying a few hours of early summer sun suffers serious sunburn, its topmost leaves shriveling up and turning black everywhere the sun touches them.
A decorative sage (Salvia splendens ‘Van Houttei’) that prefers shade went into a long-term wilt where it was planted, recovering only slightly as the days cooled off. Luckily, the heatwave only lasted two days. As soon as temps dipped back into the mid-80s, I dug it up and planted it in a more suitable spot. I had been overly optimistic about it being versatile enough to enjoy several hours of direct sun (it isn’t).
Plant in the cool of the evening
Whether you’re planting or repotting this time of year, it’s best to do it toward the end of the day. Water new or transplanted plants in well and they’ll have the dark of night for a stress-free rest before the baking sun finds them the next day. Make sure the water soaks into the ground beneath and surrounding the plant.
The second best time to plant in the heat of summer is early morning. But for that choice, find something to shade the area afterward, especially if it’s a hot, sunny day. Anything from an old umbrella to a small patio table will give some shelter to small areas. If you’re planting a large area in the blazing sun, just make sure they’re watered in well and mulched to slow evaporation of the soil surface.
Choose plants from hot climates
Plants from New Zealand and Australia have been gradually trickling onto the U.S. garden scene. And they really shine through the middle of summer. Check out the Australian Native Plant Society for more details on plants that have been hybridized for use by American gardeners. Here are four that stand up to a Midwestern heatwave.
1. Kangaroo paws: Although its unlikely most Americans can call to mind the image of a kangaroo’s paw, it’s easier to pronounce than this plant’s botanical name, Anigozanthos (Anna-go-ZAN-thus). Starting out in the U.S. as a cut flower, a few compact varieties are available now, including the Kanga series
2. Eucalyptus ‘Silver Drop’ makes a great companion for Ptilotus. With its wiry stems, it leans gently against its neighbor plants, brightening or softening any color with its silvery leaves. It makes sense, because this Eucalyptus species is native to Tasmania, an island state south of Australia. ‘Silver Drop’ is one of those multi-purpose plants—it makes a great addition to mixed containers, is a long-lasting and beautiful filler for bouquets, and its leaves smell nice.
3. For a great pot accent in sun to part shade, New Zealand flax (Phormium) beats out the typical spikes hands down. It’s also a lot more colorful. Depending on the cultivar, Phormium can grow from 2 feet to 10, and comes in colors from deep maroon to pale chartreuse. Many are striped with shades of cream to apricot and everything in between, with leaves from upright to weeping. The plant is nearly impossible to find in the Midwest, but there are a few sources on the west coast, including Foxtail Farms of California and Gossler Farms Nursery in Oregon.
4. Ptilotus (ty-LOH-tus) can be found living in the drier areas of Australia. Its flowers are like nothing else on the typical greenhouse bench, and fit perfectly in a mixed container. Picture seriously large pipe cleaners or a pointed cat’s tail, and you have a vision of their flower form. Silvery pink with darker pink tips on each “hair” draws you in for a closer look. A term used to describe the hybrid Ptilotus exaltatus ‘Joey’ is “caressable.” Seriously, this plant just makes you want to cuddle it just a bit.
Africa also churns out quite a few plants that thrive in the heat. Here are six that can usually be found at garden centers.
1. Delosperma is a cheeky little groundcover that is as easy to grow as Sedum. It’s a very short spreader that likes its conditions hot and dry, rewarding gardeners with daisy-like flowers on short stems. The species that seems to be the hardiest is nubigenum (yellow ice plant). A hybrid series with larger flowers called Wheels of Wonder, introduced by Koichiro Nishikawa of Japan, extends the color choices.
2. Eucomis, or pineapple lily is worth the wait if you start them as bulbs. They are from Africa, and most of the taller ones don’t miss a step through the hottest days as they gear up for bloom production. Eucomis montana provides nearly two months of entertainment as it sends up a stem, and each individual flower opens slowly from the bottom to the top of the 18” stalk.
3. Hemizygia ‘Candy Kisses’ is a cultivar of a newly-discovered African species of wild sage. It’s a low-grower with tri-colored leaves and a brand new name. Don’t bother practicing your pronunciation
4. Commonly known as wild dagga in its native South Africa, Leonotis leonurus is one of the best autumn-bloomers for Midwest gardeners, its bright orange flowers standing tall and attracting pollinators and humans alike. It was one of the first South African flowers to be brought back to Europe for cultivation, and is known to have been grown in Holland in the 1600’s. It’s not easy to find at garden centers because it typically doesn’t bloom until it’s at least two feet tall and doesn’t look that great until then.
5. Plectranthus ‘Mona Lavender’: as long as you keep her out of the sun, or in dappled shade, this African hybrid of the typical Swedish ivy will take the heat in stride. Ball Horticultural Company of West Chicago has been responsible for propagation and marketing this variety in the U.S. Plectranthus ‘Cerveza ‘n Lime’: It’s the leaves that make this plant special—fuzzy, fragrant, and as pinchable as baby’s toes. One of the most flexible plants around, ‘Cerveza ‘n Lime’ can go from houseplant to container anchor for the most colorful heat-lovers.
6. Scadoxus multiflorus is a plant grown for its beautiful flowers. It also has been used in Africa as an arrow poison. Yes, the plant is toxic, so care should be taken around children and pets. The tricky part comes with getting it to bloom. The varieties most often available typically push up a flower stem before the bulb forms its leaves. So if you see attractive, waxy green leaves emerging straight up out of the ground, that particular plant probably won’t bloom that season.