Here in South Louisiana, we know what extreme summer heat feels like. When temperatures stay in the high 90s (or higher) with little to no rain, younger plumerias — especially those growing in air pots — can quickly become stressed.
At Plumeria Fans Nursery, we’ve been growing plumeria for years in these exact conditions. Over time, we’ve developed a simple approach that has helped our plants get through the toughest stretches of summer heat. This guide shares what we do and what we’ve found works well for us.
Always Check the Soil First
Before you water, stick your finger about 2-3 inches into the soil.
- If it feels dry at that depth, it’s time to water.
- If it still feels moist, wait.
Never water on a strict schedule if the soil is still wet. Overwatering during heat can cause just as many problems as underwatering.
Step 1: Rehydrate First
If your plumeria is drooping or the branches are starting to wrinkle, the first thing you should do is give it a thorough watering with plain water.
Let the plant recover for 2–3 days before adding any SuperThrive or Epsom salt. Giving the plant plain water first allows the roots to start absorbing moisture again without the extra stress of supplements while it is still struggling.
What wrinkled branches mean: When branches become soft or wrinkled, the plant is dehydrated. It is losing water through the leaves faster than the roots can take it up, so it begins pulling moisture from its own stems. This is a more advanced sign of heat stress and should be addressed quickly with deep watering and some temporary shade.
Step 2: Using SuperThrive and Epsom Salt
After the plant has been rehydrated, you can use SuperThrive and Epsom salt to help support recovery.
You can safely mix them together in the same watering can.
Mixing instructions (per 1 gallon of water):
- SuperThrive: ¼ teaspoon
- Epsom Salt: 1 teaspoon
Important: Use only plain, unscented Epsom salt. Do not use scented or medicinal versions. SuperThrive is easy to find on Amazon if you don’t already have it.
How much to apply to a 1.6 gallon air pot: Use only about ½ to 1 quart (16–32 oz) of the mixed solution — just enough to thoroughly wet the soil. Do not pour a full gallon on one small pot.
Leftover Epsom salt water can be stored in a clean, sealed container for up to 2–3 weeks. SuperThrive mixed water is best used within a few days.
Sample Watering Schedule for Extreme Heat
This sample schedule is intended only for periods when temperatures remain in the high 90s and there is no rain. If we get showers or rainstorms, do not follow this schedule — always test the soil first.
Week 1
- Day 1: Plain water (if soil is dry)
- Day 4: Plain water + SuperThrive + Epsom salt (if soil is dry)
Week 2
- Day 1: Plain water (if soil is dry)
- Day 4: Plain water (if soil is dry)
Week 3
- Day 1: Plain water (if soil is dry)
- Day 4: Plain water + SuperThrive + Epsom salt (if soil is dry)
Week 4
- Day 1: Plain water (if soil is dry)
- Day 4: Plain water (if soil is dry)
Weeks 5–8 Continue alternating: one week with SuperThrive + Epsom salt, the next week with plain water only.
Temporary Shade Can Help
During the hottest part of the day, moving plants to a location that receives morning sun and light afternoon shade (or using 30–50% shade cloth) can reduce heat stress. Once the extreme temperatures ease, gradually return the plants to fuller sun so they continue to bloom well.
Signs of Heat Stress to Watch For
- Leaves drooping or wilting (even when the soil feels moist)
- Leaf edges curling or rolling inward
- Brown, crispy, or scorched leaf edges
- Yellowing or bleached-looking leaves
- Sudden leaf drop
- Soft or wrinkled branches
A few yellow leaves dropping is normal during extreme heat — the plant is conserving energy. Focus on checking the soil moisture and watering only when needed.
Final Thoughts
Extreme heat is tough on younger plumerias, but consistent care and careful observation go a long way. By testing the soil, rehydrating stressed plants first, and using SuperThrive and Epsom salt thoughtfully, you can help your plants get through the hottest weeks of summer.
If you have questions about your plumerias, feel free to reach out. We’re always happy to help fellow plumeria fans and growers.