Ten Plants That Can Take the Heat

by Andrea Laine, EMGV

Come July, I am unlikely to be outdoors — much less gardening—unless watering or weeding is absolutely required. I dislike the heat of a North Carolina Piedmont summer. Luckily for my garden and the birds and insects who visit it, there are perennials and annuals that do just fine despite the heat and even when rain is not plentiful.  

I’ve been noticing those plants more lately as it has been almost two weeks since a measurable amount of rain has fallen on my garden. And, we’ve had some very hot days, with heat indexes of 100 or more. I watered six days ago and again this morning (July 20).

Plants begin suffering physiological damage at 86 degrees and above1. Keeping up with watering is important, especially for the newer additions to the garden or those recently transplanted. An established tree, shrub or plant will fare better due to a stronger, more settled root system.  

Here are 10 plants that tolerate sunny, hot, and dry conditions reasonably well:

Perennials

Blackberry Lily or Leopard Flower (Belamcanda) This is my first experience with this semi-hardy summer bulb. It prefers morning sun, but this plant is doing very well in afternoon sun in well-drained soil. The dainty flowers began blooming in July atop stalks 30 to 36 inches high. Blackberry refers to the black seeds that follow flowering. Store corms in dry sand at 35-41 degrees.


Catmint (Nepeta ‘Walker’s Low’) This is another plant I had never grown before this year and so far I am very pleased. Lavender spikes of flowers (10 inches high) appear late spring to mid-summer and flowers are always crowded with bees, moths and butterflies. It is deer resistant. Photo credit: Debbie Roos


Lantana (Lantana Camara) The ‘Miss Huff’ cultivar is a generally reliable perennial in the Piedmont region of NC. Treat all other cultivars as annuals here. Miss Huff is a woody evergreen shrub that will grow 4’ high and wide in full sun. It blooms from late spring to fall and flowers are a mix of orange, yellow and pink. Cut it down to four to six inches in the spring before new growth begins.


Garden Sage (Salvia Officinalis) This plant is the star of my herb garden – good-looking, evergreen and productive all year. It is planted in well-drained soil and receives four to six hours of sun; that’s about as ‘full’ as my heavily wooded property allows, but obviously it has been good enough for this plant.  


Purple coneflower (Echinacea purpurea)  Being native to the southeast United States, it’s not a great surprise that the purple coneflower tolerates heat and drought. But it also tolerates humidity and poor soil and can grow in full sun or part shade. Pinkish-purple flowers appear from May to October. It is deer resistant, too. Photo credit: https://plants.ces.ncsu.edu/plants/echinacea-purpurea/

Annuals

Summer snapdragon (Angelonia angustifolia)  For years now I have relied on this annual to add color and grace to my front walkway. I choose white and purple flowering cultivars but there are pink and variegated ones, too.  It grows at a medium rate and flowers from June through September. I bet it would do well in a container. Actually, most plants that tolerate drought probably would.


Begonia x ‘Dragonwing’ This has long been my favorite begonia because it fills out so nicely. I don’t readily think of begonias as being heat and drought tolerant, but I’ve included this one because of my firsthand experience with it under exactly those conditions. I love its drooping clusters of flowers. I usually plant this in a container on my deck which receives morning sun. This year I put it in the ground outside my front door,  a western exposure that also receives a good bit of shade. As you can see, it is doing well.


Evolvulus  glomeratus ‘Blue daze’ It was serendipity when I spotted this plant in a nursery in Mebane last summer. I was through with my planting for the season (or so I told myself) but just couldn’t resist its charms. I do like plants with blue flowers. I brought it home without knowing anything about it. I put it in the ground in full sun among some perennial grasses and it proceeded to take over! I eventually learned that it is a ground cover in the morning-glory family. It’s flowers close at dusk or on cloudy days. If planted in the ground, it forms sprawling mounds nine to 18 inches tall2, which was precisely what I experienced. I would plant it again, but in a more open space. It was yet another lesson in “right plant, right place.” Photo credit: JC Raulston Arboretum


Mandevilla (Dipladenia sanderi) Every summer my mother planted this tropical vine in a container (with trellis for climbing) on her deck in Southeast Pennsylvania. In a short time, it looked spectacular. I’ve often considered doing the same, but the vines have become more expensive than I care to spend for a one-season plant. So, imagine my glee this spring when I noticed a new compact mounding cultivar for $6 in a big box store. I planted three in the ground; I mulched but have not been aggressive with water. They attract hummingbirds and butterflies. NC State Extension says they can be wintered indoors in a container.  


Portulaca grandiflora This is an old favorite of mine that I have not planted in a great while but is such a crowd pleaser. I think it might come to own this sloped spot (therefore, well-draining) among the native pink muhly grasses. There are varieties that flower in a single color, but I enjoy the ones with a variety of colors on one plant. So cheerful! Like evolvulus, the flowers close on cloudy days.

I’ll be looking to add more of these plants to my garden in future years. I am so grateful that some like it hot!


Footnotes, Resources & Further Reading

1. https://www.ahsgardening.org/gardening-resources/gardening-maps/heat-zone-map

2. https://plants.ces.ncsu.edu/plants/evolvulus-glomeratus/

https://extensiongardener.ces.ncsu.edu/extgardener-salvias-for-the-sage-gardener/

https://www.uaex.edu/yard-garden/resource-library/plant-week/begonia-dragonwings.aspx

Learn more about other plants listed above: https://plants.ces.ncsu.edu/

Unless otherwise noted, photos taken by A. Laine