If you get very hot summers, what annuals do you grow successfully?

5 years ago

I'm in central OK, z7, and this is the hottest summer we've had in a long time. My flowerbeds are awful. I did make one huge mistake in letting a certain weed take over when I thought it was last year's Lantana that reseeded. lol

I'm not having good luck with anything this year.

Other than Lantana, what annuals do you grow in 3 months worth of high heat?

Preferably those that flower all summer.

Featured Answer

Okiedawn OK Zone 7

5 years ago

Well, it depends on your definition of a very hot summer, and it depends on how much rain you're getting or how much you're able to irrigate. Also it depends on whether the plants are in full sun from sunrise to sunset or if they have shade for part of the day. More than anything else, the quality of your soil matters. In good soil, flowering plants can tolerate quite a lot of heat even in full sun as long as they are getting adequate water, whether rainfall or irrigation.

I'm in south-central OK and we tend to be both hotter and drier than central OK most years, including this year. Many of my flowers grow in well-amended clay, and are mulched with 2-4" of cypress mulch throughout the growing season. I do judge the performance of all plants by how well they did, or did not, perform in the summer of 2011, when we had less than 12" of rain from January through the end of July and we were over 100 degrees at least 76 days that year, including every single day in July (a month in which zero rain fell). Anything that survived or mostly survived 2011 is bulletproof on my list. Keep in mind that even the native cacti growing on our land where they had grown for decades died in 2011, so you wouldn't expect annual flowers to outperform any perennial natives, but a couple did. Based on 2011, these are the bulletproof annual flowers that can withstand the most heat in full sun as long as they receive at least a little irrigation when no rain is falling:

Globe Amaranth, aka as gomphrena "Strawberry Fields". (Gomphrena globosa.)This grows in unimproved clay on the edge of our gravel driveway about 300' from the house and I watered it maybe once a month in the summer of 2011.

Moss Rose. (Portulaca grandiflora). This is a succulent annual that tends to reseed for me and I grew one of the standard old varieties sold in flats in stores that year, not one of the newer and pricier hybrid varieties with substantially larger flowers. At times, the succulent stems shriveled and dried up a bit (highs were in the 110-116 range during that time frame) but being watered occasionally revived them and plumped them up again.

Tall Verbena, aka verbena-on-a-stick. (Verbena bonariensis.) These survived both in the garden and in the pasture where they have reseeded. They are butterfly magnets. They reseed vigorously, and some of them may be performing as half-hardy annuals in my garden. A very wet rainy winter season is more likely to wipe them out in my garden than a very dry hot summer.

Marigolds. (Tagetes spp.) The ones the produce the best for me and that survive heat and drought the longest are the small flowered ones. I grow them every year, always have and always will. They are more prone to spider mites in hot, dry years but I usually just blast them off the undersides of the leaves with a water hose.

Laura Bush Petunias. (Petunia x violacea). This is one specific variety of petunia native to South America, and it has been bred for heat-tolerance and disease resistance, not for large flowers. With smaller flowers than the standard hybrid petunias sold in stores, this is one tough plant. The hotter it gets, the more it blooms. The leaves do not yellow like the leaves of hybrid petunia varieties. I cut back the plants by at least 50% each month in June, July and August to keep the plants from getting too leggy and taking over everything around them. Mine have reseeded regularly since the early 2000s, and you never know where they'll pop up. In 2011, they did struggle quite a bit in the heat after I stopped watering them in July, but after rain returned in mid-August, they not only revived well and put on new growth and bloomed, but new ones popped up out of the soil from seeds that apparently matured on the plants during the earlier summer months. Seed is available from Wildseed Farms.

I don't know if these two would be annuals, half-hardy annuals or perennials for you, but they perform either as half-hardy annuals or reseeding annuals for me:

Texas Hummingbird Sage (Salvia coccinea). Seed from Wildseed Farms. These are the plain native red salvias--not bred for bigger flowers or other colors or whatever. Tough as nails. Need to be watered once or twice a month or their leaves will turn black and crispy. Reseed vigorously.

Angel's Trumpets (aka Devil's Trumpets, depending on the geographic region). I grow both Datura metal and Datura inoxia. Tough as nails. Will tolerate all kinds of heat as long as they get some water occasionally. Reseed rampantly if you don't deadhead them consistently.

So, the above are the toughest. They survive the roughest conditions in the worst years. This list is the best of the rest:

Zinnias---the older varieties tolerate heat better than the newer ones with fancier flowers. Profusion zinnia and Mexican zinnia Zinnia haageana).

Lantana. These can be annuals or perennials depending on the variety. Can tolerate extreme heat with irrigation, though sometimes the leaves roll or turn crispy. Good rainfall or a good deep watering will revive them. The toughest one I grow is Texas Lantana (Lantana horrida), which has yellow and orange flowers. I have a friend whose Mrs. Huff lantana survived 2011 in very sandy soil with a lot of watering.

Mexican Hat. (Ratibida columnifera). A native wildflower that does not survive in the pastures in very hot, dry summers, but does survive in the garden if watered once or twice a month. Reseeding annuals for me.

Purple coneflowers (Echinacea purpurea). Perennials. I have both the species and a couple of the newer purple hybrids like Pow Wow Wildberry. They need more water than most of the other flowers I grow or the leaves and petals will develop black edges in the heat, but if watered well, they do pretty well.

Celosia spicata. Similar to coneflowers, they need more water, but if they get it they remain very happy even in full sun. I just lost one this week and I'm not sure why. Maybe it did get too dry. I have about 25-30 others that are fine though.

Salvia farinacea. This is a blue-flowered wildflower type salvia. When I was growing up in Texas, we called it clary sage. It can be either an annual or a perennial, and I think that for me it usually functions more like a reseeding annual, but I have one plant in one bed that has been there since about 2006. Smaller leaves and smaller flowers than one salvias, but I believe that is what enables it to survive so well in the heat.

Gazania daisies are very tough and tolerate a lot of heat and some drought if in very well drained soil. They aren't overly fond of my clay soil (even well-amended clay) so I don't grow them often.

I hope this gives you some ideas. People who live closer to your part of the state and who have conditions more like yours might have even more suggestions than the ones that do so well for me down here near the Red River.

Dawn

Sort by:Oldest

Comments (12)

rhizo_1 (North AL) zone 7
5 years ago
Pentas, angelonia, gomphrena, celosia, statice, and some zinnia varieties do perfectly here in my sunny annual beds. I have non-irrigated red clay soil, which is not amended but kept well mulched. My annual season is from April/May through September/October. I grow most of my annuals from seed and put them out, flowering, after our last expected frost.

All of the plants are highly pest resistant, drought tolerant, heat and sun loving. They never need a summer vacation but keep on blooming from spring until frost. Northern Alabama can be brutal sometimes in the summer and each of these are true winners for me year in and year out.

I've actually given up on lantana due to mites, lantana lacewing, and the need for dead heading, a gardening task I don't enjoy.
Related Discussions
whats the best annuals and when do you plants annuals
Q
Comments (2)
seedboy, I don't know that there are 'best' annuals. But there is a very long list of great performers under a wide range of conditions. You'll need to evaluate the locations on your property for such factors as sunlight (how long and how much), soil conditions, and drainage. In Florida, you'll have plenty of options for the warm and hot months (spring and summer) as well as the cooler times (fall and winter). For example, this is not the time of year, in your location, to buy a flat of pansies. Though they may look wonderful at the garden center, they will only perform well for a very short time due to the heat. Fall is the time to plant them, for an all winter-long dispay. If you visit the Florida Forum, be sure to ask what their FAVORITE annuals are. I'm sure that people are likely to list such plants as marigolds, zinnias, gomphrena, Catharanthus roseus, portulaca, and lantana (which is a tender perennial but used as an annual.) And MANY more.
...See More
How do I successfully grow Impatiens from seed?
Q
Comments (8)
Good news everyone! I started my impatiens March 1st and today is March 5th and they all are sprouting! Yay! I can barely believe how quick they germinated the packet says for one flat in 14-21 days the other flat ( different variety impatiens) says 21-28 days till germination. All I can say is thats a blessing for sure! I been keeping the light on the seeds 24/7 and it has been a steady temp between 73-78 (soil temp) since I turned the one out of two light fixtures off the second day. I will most likely remove the dome once the seeds have lost there shell. Then once they all are completely germinated I will turn the light off at night, it generally doesn't fall below 65f when the light is off. Does this sound like a good idea???
...See More
Can I grow annuals successfully?
Q
Comments (4)
A metal halide can exceed the intensity of direct sunlight if you get close enough. Your plants would all die of course! Anyway, you should be able to flower maybe 30-50 square feet of annuals with one or both bulbs.
...See More
Anyone growing these roses? How do they do in hot summers?
Q
Comments (6)
During its blooming cycles, Pomponella is a heavy bloomer, but it tends to take its time moving from one blooming cycle to the next one, and one or more of those "rest periods" tend to occur during the hottest part of our summers (July and Aug. temps often in high 90s or 100s). Fortunately, it's a nice looking bush--and that is all you will be looking at as you wait in the heat a month or 6 weeks for its next blooming cycle to begin. I should admit that my Pomponella is only in its second year in my garden. By years 3 or 4 or 5, it might exhibit very different characteristics. Kate
...See More
slowpoke_gardener
5 years ago
This is very interesting. I am growing a zinnia mix in my wildlife area, I wanted a native mix that would grow taller than the grass and weeds. I ask at the farmers coop and all they had to offer was a wild flower mix at $25 a pound, I thought I would pass on that because I have no idea what is in a wild flower mix. I will be trying to learn more about these flowers.

Thanks to both of you.
juneroses Z9a Cntrl Fl
5 years ago
Others to consider are those on the Texas Superstars site:

http://texassuperstar.com/plants/index.html

I'd give top consideration to those recommended by Okiedawn, however. Her/his garden probably gets more of the type of care you or I could give to the garden as compared to a trial garden.
Oakley
Original Author
5 years ago
Thank you so much, I'm writing these down.

Dawn, I'm sure like your's, our summer began unusually early. We had the hottest May on record and basically no Spring. Not even a tornado warning. lol None of the annuals really had time to get used to the heat, it was immediate.

Years ago I grew Globe Amaranth and I forgot how great they did.

I've grown Celosia a few times and they didn't do that well, but this is the first year they reseeded, and those plants are doing better than the originals.

One plant I have that's thriving in the heat is Calibrachoa (Million Bells) that I'm growing in a pot. It's in the Petunia family and I can't grow a Petunia for the life of me!

I'll definitely check out Laura Bush.

My Clematis are doing good and I'm waiting on the second flush of flowers.

One interesting thing I've noticed, other than Pentas, is that red plants don't do well in my flowerbeds.

Yesterday's weather was perfection. Dawn, did you get that cool front? It blew down all of my Cosmos that were staked.

Keep the suggestions coming! I've been whining all summer because my gardens are usually pretty good.
User
5 years ago
last modified: 5 years ago
In addition to great ones already mentioned (pentas, portulaca, globe amaranth), my list of tried and true annuals with 20+ yrs of having every year, 3 different houses, in brutal Texas conditions. Heat (100+ temps for weeks to months), full sun lovers, drought-tolerant, constant blooms, no issues:

Crossandra. Great plant. Well-behaved, pretty, glossy leaves, no deadheading needed, no insects, blooms non-stop ...

Bougainvillea ...

Mandevilla (it’s nearly to the top of the obelisk now) ...

Pentas this year ...

Portulaca at last house ...

Zinnia ‘Profusions’ (reseeding annual) are another. I haven’t planted them here yet, but they did great at my other houses.

——-

One I’m trying this year for the first time: Sunpatiens. I’m impressed with them. I lost two that were in a damp, shady bed, to root rot ... but these two in afternoon sun (1pm on) and only watered twice a week, are thriving.
Oakley
Original Author
5 years ago
Your flowers are gorgeous! We both do the same thing with flat rocks in the flowerbeds.

I bought a Mandevilla last summer and it took until the end of the summer for it to bloom.

This picture was taken in September. Never again.

For everyone, do you usually fertilize all plants or only a select few?
Okiedawn OK Zone 7
5 years ago
Oakley, We did get some of the cool front, but not as much as folks further north. At least we got a little bit of it though. It was cool for two or three days and nights and I have loved every minute of it. Tomorrow our temperatures are supposed to return to average July highs, but we aren't expected to be in the 110-113 range like we were a few days back, so how bad can the upper 90s and lower 100s really feel compared to that hot mess we just came through? We're in drought, though, so the plants here are deteriorating really quickly, even if irrigated.

There is very little green here, other than the trees in our woodland. My garden is still mostly green because I've been watering it a lot, but I've got to stop pouring water on a lost cause.

I would like to get out tomorrow before it gets too hot and mow the grass in the pastures down really short. Usually I don't do that because the wildflowers are in bloom, but the drought and heat have dried up all the wildflowers, so I should mow things down short to reduce the fire risk (a perpetual hazard living in a grassland area, although at least our grassland is interspersed with woodland areas along the creeks). I'm just afraid I'll fall into the big cracks in the ground and disappear....and my husband will come home to am empty house and a missing wife. lol. Drought humor. It is getting harder and harder to find anything to laugh about here.

A couple of nights ago, my husband shot a rattler that had gotten about 3' away from our old dog. They were near our back steps. That's the closest we've had a rattlesnake get to the house in a long time---usually they are a problem a bit farther out from the house. I guess the drought is driving them in. Today when I was out there watering periwinkles in pots near the steps, I was watching the ground very, very carefully. We keep the grass there mowed down pretty short because of all the snakes, but our 13-year-old dog still never saw that rattlesnake. If Tim hadn't been with the dog, I bet the snake would have bit him. I hate hot dry summers, and this one has been a pretty tough one. I wish autumn would come on and get here. Usually the rain down here returns in Sept or Oct in all but the worst drought years, so I'm pinning my hopes on an early autumn.

Dawn
Oakley
Original Author
5 years ago
Dawn, when you said you were afraid of falling into a big crack, it reminded me of a video I saw a couple of weeks ago where hundreds of rattlers gather together in crevices. We're a county away from rattle territory and I'm sure there are some here too.

Our dog attacks snakes and I hate it. He'll be outside and we hear a special kind of bark and I immediately know he has a snake. They've been long bull snakes & he grabs them then bites them in half. Ugh

We have grassland (pasture) and wheat fields surrounding our house, we don't farm though, but one hot summer when the pasture was dry, lightening hit it and our acre was surrounded by fire. It's a very scary thing & the first time my mouth went completely dry in an instant!

Last year I grew Periwinkles in pots, and they were probably the prettiest flowers all summer. They reseeded nicely, but it takes too long for them to bloom.

We're back in the 90's today. The mornings have been great. I spend an hour in the flowerbeds as soon as the sun comes up, and I'm usually full of sweat when I come inside.

I finally looked at the rain gauge this morning from the storms we had the other night because I heard on the news people got 4". We got 4" exactly! The beds are still damp which saves me a lot of time.
Saypoint zone 6 CT
5 years ago
I have west facing window boxes that take a beating, and am having very good results with both Scaevola and Catharanthus, provided they get enough water. The heat doesn’t bother them at all. Also in the boxes are Petunias, which I’ve had to spray for bud worm, but looking great as long as I stay on top of it.
Nancy RW (zone 7)
5 years ago
I loved you posing that question, Oakley, and getting this subject reviewed by the rest of you. Your photos are gorgeous, Miz--and I'd never hear of Crossandra. What zone are you in; do you have to overwinter it indoors?

We're north of some of you (NE OK), and I don't have full sun. But many of the full sun ones do well here with 3-4 hours of sun, so still a good list for me to have.
User
5 years ago
Thanks, Nancy! I’m in 8a (D/FW area). I’ve never tried to overwinter them because I don’t have the room, so I just plant them as annuals every year. I know people who have brought them inside during winter, and they did fine. Our winters here do get too cold for them.