It is essential to select from the best heat tolerant dahlias if you are growing dahlias somewhere like Florida or other Southern States of the USA, or if you are even trying to grow dahlias in a tropical climate.
The same applies if you are growing dahlias in parts of Australia. I lived there for ten years and we had substantial periods of intense heat, with temperatures over 40°C (104°F), that were a real threat to my dahlias and other garden plants.
What is more, the effects of climate change mean we see increasingly frequent prolonged heatwaves in Europe and elsewhere. Therefore, finding the best dahlias for heat might be something we dahlia growers need to do, wherever we are in the world.
Of course, dahlias need warmth and they need to be placed in a sunny spot. But dahlias originate from mountainous regions with sun, but cooler nights. It follows, then, that they are better adapted to those kinds of conditions.
This means that if you have conditions that will expose dahlias to very high temperatures over long periods, and/or searing hot sun, you will find that not all dahlia cultivars will do well.
This article is therefore aimed at helping you find the best heat tolerant dahlias. You’ll find recommendations from hot climate dahlia growers, and you will find more than a hundred cultivars listed in the table below.
These recommendations are therefore going to help you if you are growing in the USA and especially if you are looking for the best dahlias for zone 9, (zones 9a and 9b), zone 10, and zone 11.
Obviously, these dahlias will do well in other zones too – it is just that they are better adapted than others to the warmest conditions.
Recommended dahlias for heat
- Peaches N Cream
- Rose Toscano
- Blyton Softer Gleam
- Snoho Doris
- Robin Hood
- Valley Rust Bucket
- Jessie G
- Dark Spirit
- Parkland Tribute
- Ferncliff Spice
- Black Satin
- Camano Zoe
- Sylvia Craig Hunter
- Orange Globe
- Woodland Wild Thing
- Wyn’s Moonlight Sonata
- American Beauty
- Gitts Crazy, and
- Hollyhill Black Beauty.
Selection of the best heat tolerant dahlias
I’ve gone through the various sources and, for convenience, I’ve set out below a selection of more than 100 of the best heat tolerant dahlias you will find.
|Dahlia Cultivar Name||Dahlia Type/Variety||Colours|
|AC Abby||Cactus||Yellow and Red|
|AC Ben||Semi-Cactus||Orange and Yellow|
|Amy K||Semi-Cactus||Pink and White|
|Audrey Grace||Formal Decorative||Red|
|Bishop of Llandaff||Peony||Dark Red|
|Brian R||Formal Decorative||Lavender|
|Bristol Fleck||Decorative||Purple and White|
|Camano Buz||Formal Decorative||Organge|
|Croydon Masterpiece||Informal Decorative||Bronze|
|Downham Royal||Mini Ball||Purple|
|Dueil Du Roi Albert||Decorative||Dark Red|
|Elsie Huston||Informal Decorative||Dark Pink|
|Felida Stars & Stripes||Stellar/Star||Dark Orange and Red|
|Ferncliff Copper||Formal Decorative||Bronze|
|Ferncliff Illusion||Informal Decorative||White and Yellow|
|Gaylen Rose||Formal Decorative||White|
|Ginger’s Baby||Formal Decorative||Purple and White|
|Gitts Attention||Informal Decorative||White|
|Glen Valley Cathy||Semi-Cactus||Yellow and Red|
|Gloriosa||Formal Decorative||Yellow and Red variegated|
|Gonzo Grape||Formal Decorative||Purple|
|Greendor||Ball||Yellow and Red variegated|
|Hamilton Lillian||Formal Decorative||Orange|
|Hann Hitosuji||Cactus||Pink and Yellow|
|Harry Megos||Informal Decorative||Yellow and Orange|
|Hart’s Blood Red||Formal Decorative||Red|
|Hart’s Dr McMurry||Informal Decorative||Orange|
|Hollyhill Quintessence||Semi-Cactus||Pink and White|
|Hollyhill Spider Woman||Novelty Double Center||Purple and White|
|Ivory Palaces||Informal Decorative||Yellow|
|Kari Fruit Salad||Cactus||Pink and Yellow|
|Kelvin Floodlight||Formal Decorative||Yellow|
|Kenora Frills||Lacianated||Dark Pink|
|Kenora Majestic||Cactus||Yellow and Red|
|Kenora Sunset||Semi-Cactus||Yellow and Red|
|Little Laura||Mini Ball||Yellow and Orange|
|Lupin Sheila||Orchid||Pink and White|
|Manor Jubilee||Informal Decorative||Dark Red|
|Midnight Star||Orchid||Dark Red|
|Mingus Alex||Informal Decorative||Dark Red|
|Mingus Phillip||Semi-Cactus||Lavender and White|
|Mom & Dad||Semi-Cactus||Pink and Yellow|
|Ms Julie||Stellar/Star||Red and White|
|Ms Prissy||Stellar/Star||Dark Red|
|North-West Cosmos||Single||Lavender and Purple|
|Olson’s Folly||Formal Decorative||Orange and White|
|Oreti Stacy||Lacianated||Pink and White|
|Penhill Watermelon||Informal Decorative||Bronze|
|Pooh||Collarette||Yellow and Red|
|Prince Noir||Informal Decorative||Dark Pink|
|Purple Joy||Formal Decorative||Purple|
|Ruthie G||Waterlilly||Pink and Yellow|
|Ryecroft Jan||Formal Decorative||White|
|Sam Hustom||Informal Decorative||Orange|
|Sir Richard||Mini Ball||Dark Pink|
|Snoho Peggt||Ball||Dark Pink|
|Spring Flag||Semi-Cactus||Pink and Yellow|
|Sterling Silver||Formal Decorative||White|
|Taratahi Ruby||Waterlilly||Lavender and White|
|Tartan||Informal Decorative||Dark Red and White|
|Thomas A. Edison||Formal Decorative||Purple|
|Tyler||Formal Decorative||Purple and White|
|Veronne’s Taylor Swift||Stellar/Star||Yellow and Red|
|Verrone’s Pink Giraffe||Orchid||Lavender and Pink|
|Walter Hardistry||Informal Decorative||White|
|Wheels||Collarette||Yellow and Red|
|White Nettie||Mini Ball||White|
|Wine and Roses||Waterlilly||Purple and White|
|Wine Frost||Waterlilly||Red and White|
Growing Heat Tolerant Dahlias
Adjust your timings
Dahlias more or less stop growing when temperatures get really high, so the plants self-regulate to some extent, going partially dormant until temperatures cool down.
So, where temperatures are continually hot throughout the summer, you will probably find that you’ll have more success with dahlias, including heat tolerant ones, if you plant them out in September to bloom through the cooler months of autumn.
Soil and Location
When growing dahlias in hot climates, managing soil and location is crucial. Dahlias prefer a well-drained soil, rich in organic matter. It is essential to choose a location with morning sun and some light afternoon shade to prevent the plants from overheating.
Consider investing in some shade netting or shade cloth if you have no natural shade. In my experience this can make a big difference.
Dahlias grown in hotter climates need to be well hydrated to thrive. Deep and regular watering is crucial for their root system. It’s best to water the plants early in the morning or late in the evening to minimise evaporation.
You also need to pay close attention to the ongoing moisture levels in the soil as dahlias are sensitive to dry conditions. They do a lot of growing in a short space of time and they need plenty of water to make that happen.
However, don’t allow the soil to be saturated for long periods. Good drainage is essential, otherwise the roots and tubers may rot.
Mulching and Heat Protection
It is important to apply a good layer of mulch around dahlias in hot climates – I apply mulch 4 to 5 inches deep in extreme conditions. This can help regulate the soil temperature, keeping the sensitive feeder roots cool. Mulch options include home made compost, wood chips, bark, herbicide-free straw, hay, or leaves. Mulching also helps to retain soil moisture and keep weeds at bay.
In addition, it is a really good idea to mist your dahlia plants when the heat is intense, especially in the afternoon heat. You can rig up an automated misting system or just get out there and turn your hose to the fine spray setting. Obviously, an automated system is likely to be be more regular and reliable, and therefore the better option if high heat is constant throughout the summer where you are.
Pruning and Deadheading
Proper pruning and deadheading are essential for promoting flowering. To encourage bushier growth and increased flowering, pinch or cut back the main stems when the plant reaches about 12 to 18 inches in height. Regularly remove spent blooms, also known as deadheading, to stimulate more flowers and extend the flowering season.
It is also worthwhile keeping an eye on the plant’s health and remove any yellow or damaged leaves. This not only improves the plant’s appearance but also helps prevent the spread of diseases and promotes better air circulation.
Protecting from Pests
Dahlias can attract various pests like aphids, spider mites, and thrips. It is crucial to inspect plants regularly for any signs of pest infestation. Remove pests by hand or use a mild insecticidal soap or neem oil to help control them. Additionally, consider planting dahlias alongside other flowers like marigolds, which are known to repel pests naturally.
More on Growing Dahlias
You can also get much more guidance on growing dahlias in these posts:
- Taking care of dahlias: the trick with deadheading
- Dahlia pinnata: a dahlia original
- When to plant dahlia tubers: solving the dahlia grower’s eternal dilemma
- How to grow dahlias: the complete guide to dahlia care
- How to overwinter dahlia plants and tubers
- All you need to know about dahlia tubers and dahlia bulbs
- Dahlia varieties: your complete guide to all types of dahlias
- Dahlias in my garden: Six on Saturday
- Dahlia Wizard of Oz – Beautiful pink pompon dahlia
- Can you grow dahlias in raised beds?
- Do dahlias grow in Florida?
- Dahlia Wine Eyed Jill
- Can you grow dahlias in a tropical climate?
- Dahlia Ivanetti: magnificent magent dahlia
- Dahlia Night Silence – dusky pink dahlia beauty
- Visit a dahlia farm near you
- Best mulch for dahlias: a comprehensive guide
- Dahlia Islander: large, pink, loud, showy. What’s not to like?
Martin Cole has been an avid gardener for more than 20 years and loves to talk and write about gardening. In 2006 he was a finalist in the BBC Gardener of the Year competition. He is a member of the National dahlia Society.
He previously lived in London and Sydney, Australia, where he took a diploma course in Horticultural studies and is now based in North Berwick in Scotland. He founded GardeningStepbyStep.com in 2012. The website is aimed at everybody who has been bitten by the gardening bug and wants to know more.
Gardening Step by Step has been cited by Thompson and Morgan, the UK’s largest mail order plant retailer, as a website that publishes expert gardening content.
Check out my comprehensive step by step guide, with plain language explanations and ultra-useful images and illustrations. This is for you if you love dahlias and want to the best out of the dahlias you grow.