Summer’s heat can be a killer for some plants, and I’ve learned the hard way that not all greenery can handle the scorching sun.
Over the years, I’ve watched some of my favorite fragile plants wilt away, no matter how much I tried to keep them cool. It’s a bummer when they just can’t handle the heat, especially after all that effort.
If you’ve had your fair share of garden heartbreaks, you’ll want to know which plants just can’t survive those blazing summer days.
Here are 20 fragile plants that just don’t stand a chance when the temperature spikes.
1. Delicate Impatiens
Bright and cheerful when temperatures are mild, these colorful bloomers quickly show their displeasure when the mercury rises. Impatiens wilt dramatically in direct summer sun, with their stems turning limp and flowers dropping within hours of heat exposure.
Their shallow root systems can’t pull up enough moisture to compensate during hot spells. Even with consistent watering, sustained temperatures above 85°F cause them to decline rapidly.
For any chance of summer survival, they need deep shade, consistently moist soil, and protection from hot afternoon sun. Many gardeners simply treat them as temporary spring flowers rather than fighting the inevitable summer decline.
2. Fussy Fuchsias
Hanging like delicate dancers from baskets and containers, these stunning flowers captivate with their two-toned blooms. Fuchsias absolutely detest hot weather and begin to falter once temperatures exceed 80°F.
Their elegant blossoms drop rapidly during heat waves, leaving behind bare stems and disappointed gardeners. Native to cool, misty environments, fuchsias evolved without the biological mechanisms to handle high temperatures.
Morning sun followed by afternoon shade might save them in milder climates, but in truly hot regions, they’re best enjoyed as spring or fall plants. Some gardeners move their potted fuchsias to cool, shaded porches during summer’s peak to preserve them.
3. Vulnerable Violets
Sweet and nostalgic, these dainty flowers bring charm to spring gardens but vanish when summer intensifies. Violets retreat underground when temperatures climb, their delicate leaves curling and browning at the edges before disappearing entirely.
Both African violets (indoor) and garden violets (outdoor) share this heat sensitivity. Their velvety leaves lose moisture rapidly in hot, dry conditions, causing irreversible damage to their cellular structure.
Growing naturally in woodland settings with filtered light and consistent moisture, violets simply aren’t equipped for harsh sun exposure. Gardeners in hot climates must treat them as seasonal treasures to be enjoyed briefly before summer’s arrival forces them into dormancy or death.
4. Struggling Sweet Peas
Beloved for their cottage garden charm and intoxicating fragrance, these climbing beauties fade fast when temperatures rise. Sweet peas begin to struggle once daytime temperatures consistently reach above 75°F, their delicate blooms shrinking and stems becoming stringy.
The plants evolved in cool maritime climates, explaining their poor tolerance for heat and humidity. Once summer heat arrives in earnest, sweet peas quickly develop powdery mildew, stop flowering, and ultimately collapse.
Even with ample water, they simply cannot physiologically handle high temperatures. Gardeners in warm climates often plant them in late fall for winter and early spring blooms, accepting that they’ll be gone before true summer arrives.
5. Temperamental Tuberous Begonias
Flamboyant and showy during cooler months, these stunning flowers quickly show distress when temperatures climb. Tuberous begonias develop crispy, brown edges on their normally lush petals when exposed to temperatures above 85°F for even short periods.
Their fleshy stems and succulent-like leaves lose turgor pressure rapidly in heat, making recovery difficult even with increased watering. Originating from cool, mountainous regions, these begonias evolved for moderate temperatures with high humidity.
Extended heat exposure causes their tubers to go dormant prematurely or rot if soil moisture isn’t perfectly balanced. Many gardeners in hot regions have given up growing these beauties outdoors, reserving them for containers that can be moved to cooler locations during heat waves.
6. Perishing Pansies
Cheerful faces that brighten spring gardens become sad spectacles once summer heat arrives. Pansies quickly develop leggy, weak stems and tiny, insignificant flowers when temperatures consistently exceed 80°F.
Their compact root systems can’t support their water needs during hot weather. Even daily watering won’t save them once real summer heat sets in – they’re genetically programmed to decline as temperatures rise.
Many southern gardeners treat pansies as winter annuals, planting them in fall for winter color and removing them by late spring. Northern gardeners might get slightly longer enjoyment but still watch their pansies fade by midsummer. Their heat-induced decline is so predictable that experienced gardeners plan for their replacement rather than fighting the inevitable.
7. Languid Lobelia
Cascading from containers with brilliant blue flowers in spring, these delicate annuals surrender quickly to summer’s intensity. Lobelia begins shutting down flowering and developing crispy foliage once temperatures consistently reach above 80°F.
The plants evolved in cool coastal regions and simply lack the physiological adaptations for heat tolerance. Their shallow roots can’t access enough moisture to compensate for water loss through their fine foliage during hot weather.
Some newer varieties claim improved heat tolerance, but even these struggle in truly hot climates. Gardeners in warm regions often watch their gorgeous spring lobelias completely disappear by midsummer, regardless of care. In very hot areas, they’re best treated as temporary spring color rather than season-long performers.
8. Melting Maidenhair Ferns
Graceful and ethereal with their delicate fronds, these woodland treasures quickly become garden heartbreak in summer heat. Maidenhair ferns respond to temperatures above 85°F by rapidly browning around the edges and then collapsing entirely if conditions don’t improve.
Their natural habitat is cool forest floors with consistent moisture and humidity. When exposed to dry heat, their thin fronds lose moisture faster than their roots can replace it, leading to crispy, dead foliage.
Even indoor specimens struggle near windows during summer or in rooms with dry air conditioning. Without very specific microclimate conditions – consistently moist soil, high humidity, and protection from hot air currents – maidenhair ferns simply can’t survive summer heat in most regions.
9. Collapsing Columbines
Dancing like woodland fairies in spring gardens, these native wildflowers retreat dramatically when summer temperatures soar. Columbines respond to extended heat by yellowing their previously lush foliage and ceasing all flowering activity.
Naturally adapted to cool mountain meadows where they receive spring moisture followed by dry summer dormancy. In garden settings with regular irrigation, this dormancy often becomes death as their crown rots in the combination of heat and moisture.
The delicate, lacy foliage that makes them so attractive also increases their surface area for water loss. By midsummer in hot regions, columbines typically disappear entirely or persist as struggling remnants of their spring glory, regardless of care provided.
10. Withering Wishbone Flowers
Dainty and prolific in spring containers, these small bloomers (Torenia) fold under pressure when real summer heat arrives. Wishbone flowers develop scorched leaf edges and significantly reduced flowering once temperatures consistently exceed 85°F.
Their natural habitat in Southeast Asian highlands gives them poor adaptation to North American summer heat. The plants simply lack the waxy leaf coating and efficient water-use mechanisms needed for hot weather survival.
Even with diligent watering, they struggle to maintain turgor pressure in their stems and flowers during heat waves. Many gardeners in warm climates have learned to enjoy them as spring annuals, replacing them with more heat-tolerant options by early summer rather than watching them decline throughout the hottest months.
11. Failing Forget-Me-Nots
Carpeting spring gardens with sky-blue blooms, these cottage garden classics become forgettable brown messes in summer heat. Forget-me-nots quickly develop powdery mildew and collapse when temperatures consistently rise above 80°F.
Their natural lifecycle involves setting seed and dying back as temperatures rise. In garden settings, this natural dieback often gets mistaken for poor heat tolerance, but it’s actually their normal reproductive strategy.
The hairy leaves that give them a soft, fuzzy appearance also make them particularly susceptible to fungal issues in hot, humid conditions. Gardeners in warm climates learn to appreciate forget-me-nots as ephemeral spring beauties that will reliably self-seed for next year rather than trying to extend their season through summer.
12. Drooping Dahlias
Stunning and architectural when conditions are right, these show-stopping flowers quickly lose their composure in extreme heat. Dahlias begin wilting dramatically when temperatures exceed 90°F, even with adequate soil moisture.
Their large, dinner-plate sized blooms act like solar collectors, absorbing heat and losing moisture rapidly. During extended heat waves, dahlias may not only drop flowers but also develop stunted growth and increased susceptibility to spider mites and powdery mildew.
While not always killed outright by heat, their quality declines so significantly that many gardeners in hot regions have abandoned growing them. Without afternoon shade and consistent moisture, dahlias simply cannot maintain their spectacular display through the hottest months in warm climate zones.
13. Languishing Lady’s Mantle
Magical in spring with water droplets collecting on its scalloped leaves, this perennial becomes a brown, crispy mess by midsummer in hot regions. Lady’s mantle leaves scorch around the edges and eventually die back completely when exposed to temperatures consistently above 85°F.
Native to cool European woodlands and meadows, it evolved without mechanisms to handle serious heat stress. The same fuzzy leaves that create its signature dewdrop effect also increase surface area for water loss during hot weather.
Even consistent irrigation cannot overcome its genetic programming for cool conditions. In southern gardens, lady’s mantle often disappears entirely by midsummer, while northern gardeners may see it persist in a diminished state if given afternoon shade and regular moisture.
14. Surrendering Snapdragons
Bright and cheerful in spring displays, these vertical bloomers quickly surrender their flowering when summer temperatures climb. Snapdragons respond to consistent temperatures above 85°F by producing significantly smaller flowers or stopping bloom production entirely.
Their growth becomes stunted and leggy as they struggle to cope with heat stress. Originally Mediterranean plants, modern snapdragon varieties have been bred for showier blooms at the expense of their ancestral heat tolerance.
In southern gardens, snapdragons are typically grown as winter annuals for spring bloom, then removed before summer. Northern gardeners might see them persist longer but still watch flowering decline sharply during summer heat waves. Without significant breeding breakthroughs, snapdragons remain firmly in the category of cool-season flowers.
15. Failing Foxgloves
Towering and dramatic in spring gardens, these cottage garden staples rapidly decline once serious heat arrives. Foxgloves respond to temperatures above 85°F by developing yellowing lower leaves and failing to produce their signature tall flower spikes.
Evolved for cool, dappled woodland settings in Europe, they lack the physiological adaptations for heat tolerance. Their large, fuzzy leaves lose moisture rapidly in hot, dry conditions, causing the entire plant to wilt dramatically even with adequate soil moisture.
Most foxglove species are biennial, meaning they grow foliage the first year and flower the second before dying. Summer heat often accelerates this natural die-off, causing gardeners to mistakenly blame the weather for what is partially a normal lifecycle completion.
16. Perishing Primroses
Cheerful harbingers of spring that quickly become summer casualties when temperatures rise. Primroses develop scorched, browning leaves and completely cease flowering when exposed to temperatures consistently above 80°F.
Their natural mountain meadow habitats feature cool, moist conditions year-round. When transplanted to typical gardens, they lack the physiological mechanisms to handle heat and drought stress.
Even consistent watering cannot overcome their genetic programming for cool weather. Many gardeners have learned to appreciate primroses as temporary spring displays rather than permanent garden fixtures. In all but the coolest climate zones, primroses typically disappear entirely by midsummer, returning to dormant roots if they survive at all.
17. Crestfallen Cineraria
Vibrant and daisy-like in spring displays, these colorful potted plants collapse dramatically in summer conditions. Cineraria leaves wilt and flowers shrivel within hours when exposed to temperatures above 80°F, regardless of soil moisture.
Native to cool, misty Canary Islands mountain regions, they evolved without heat-tolerance mechanisms. Their large, soft leaves create excessive surface area for water loss during hot weather.
Few plants show heat stress more quickly or dramatically than cineraria. Many florists and garden centers sell them as disposable color spots for spring, knowing they’ll decline rapidly as temperatures rise. Even indoors, they struggle with summer heat and dry air conditioning, making them truly temporary decorations rather than lasting houseplants.
18. Miserable Mimulus
Cheerful monkey flowers that bring spring streamsides to life quickly surrender when summer heat intensifies. Mimulus plants develop crispy brown leaf edges and stop flowering entirely once temperatures consistently exceed 85°F.
Their natural habitat along cool mountain waterways explains their poor adaptation to conventional garden conditions. Even consistent moisture cannot compensate for their genetic programming for cool air temperatures.
In hot climates, mimulus typically disappear by early summer regardless of care provided. Some gardeners in cooler regions manage to extend their season by planting them in consistently wet areas with afternoon shade, but even there, they rarely persist through the hottest weeks of summer without significant decline.
19. Suffering Spring Bulbs
Glorious in early spring, bulbs like tulips and daffodils quickly disappear when temperatures climb. Their foliage yellows and dies back naturally as spring transitions to summer, often leading gardeners to believe they’ve done something wrong.
Spring-flowering bulbs evolved in regions with wet winters and springs followed by hot, dry summers. Their natural lifecycle includes going dormant underground during summer heat.
Continued watering during their dormant period often leads to bulb rot and failure to return the following year. While not technically killed by heat, their disappearing act coincides so precisely with rising temperatures that they belong firmly in the category of plants that “die” in summer – at least from the garden’s visual perspective.
20. Languishing Ligularias
Bold and architectural with their large leaves, these woodland perennials quickly show distress in summer heat. Ligularias develop dramatic wilting even with moist soil when temperatures exceed 85°F, their large leaves drooping like deflated balloons.
Native to cool woodland streams and boggy areas in Asia, they evolved for consistent moisture and protection from intense sun. Their enormous leaf surface area creates excessive water loss during hot weather that their roots simply cannot replace quickly enough.
Without very specific microclimate conditions – consistently moist soil, high humidity, and protection from hot afternoon sun – ligularias simply cannot maintain their impressive appearance through summer heat. Many gardeners have abandoned growing them after watching repeated summer meltdowns.