Have you ever wondered if and how bougainvillea would come back after a freeze? I found out firsthand the answer to this question first this past year. Here’s an update on how my bougainvillea (actually bougainvilleas but the one I focus on got hit the hardest) is doing 9 months after a freeze.
I live in Tucson Arizona, which is USDA hardiness zone 9b. The winter of 2018/2019 was cold—for us desert dwellers anyway. A few nights dipped into the mid to upper 20s and most of the bougies in town got hit.
I received lots of questions and comments from readers and viewers regarding this topic, especially in January. The temperatures dipped in parts of Arizona and California so people were unsure if their bougainvillea would come back.
My bougainvilleas actually got hit by 3 nights of below-freezing temperatures. These nights were staggered over weeks which was good. Consecutive freezing nights can do a bougainvillea in because that’s when the roots get damaged.
This wall of bougainvilleas grows in Santa Barbara where I lived for 10 years. The evening temps rarely dipped below 40F so the danger of freeze damage here is slight.
Over half of my Bougainvillea Barbara Karst initially looked like it was dead but only the foliage and branches received the damage. The roots were just fine. By the end of winter, all but a few lower branches were looking dead.
You can see what I mean by clicking on the 2 links below to see how it looked and what I did in April.
I’m going to answer some questions 1st and then give you a timeline of what went down with these freezes. You’ll also find out what I’ve done and how it affected the bloom. Barbara Karst is a vigorous grower and a big bloomer so it’s a good indicator. My other 3 bougainvilleas aren’t as floriferous.
Barbara Karst bougainvillea is a popular variety known for its vibrant pink-purple bracts that add color to gardens However, this tropical plant native to Brazil is not cold hardy and requires protection from frost and freezing temperatures. Even a light frost can damage the leaves, bracts and branches. In extreme cold, the entire plant can die back to the ground.
By understanding the plant’s vulnerability and taking appropriate measures, you can safeguard your Barbara Karst bougainvillea from frost damage This ensures its survival over winter and a vigorous return in spring
Signs of Frost Damage on Bougainvillea
It is important to recognize early signs of cold injury on bougainvillea so prompt action can be taken:
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Wilting and drooping of leaves and bracts
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Leaves turning yellow or brown, especially around the edges
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Blackened, dried out foliage and flowers
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Defoliation as leaves and bracts drop from the plant
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Dieback of stems and branches
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Lack of new growth
At the first indication of frost damage, implement protection methods before the next cold spell. Timely action can save your plant.
Ideal Temperature Range
Barbara Karst bougainvillea thrives in warm conditions:
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Preferred daytime temperatures: 65-85°F (18-29°C)
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Minimum temperature: above 40°F (4°C)
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Can tolerate short periods down to 30°F (-1°C)
When temperatures drop below 30°F, frost damage occurs. Protect plants once night temperatures near freezing.
Methods to Protect Bougainvillea from Frost
Here are some effective techniques to safeguard barbara karst bougainvillea:
Choose a Sheltered Location
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Plant against a sunny, south-facing wall for radiant heat.
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Avoid frost pockets in the landscape.
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Grow in containers that can be moved into shelter.
Provide Insulating Mulch
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Apply 4-6 inches of bark, leaves or straw around the base to protect roots.
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Prevent mulch from touching the stems to avoid rot.
Cover the Plants
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Drape plants with frost cloth, burlap or blankets before dusk.
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Support covers above foliage without compressing it.
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Remove covers daily to avoid overheating.
Use Heaters and Lights
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Position outdoor heaters or strings of incandescent lights near plants.
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Aim heat lamps towards foliage but keep a safe distance.
Water Well Before Frost
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Moist soil retains more heat than dry ground.
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Don’t overwater to prevent root rot.
Prune Damaged Growth
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In spring, remove dead stems to allow new shoots.
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Sterilize tools between cuts to prevent disease spread.
Caring for Frozen Bougainvillea
Even with the best precautions, an unexpected severe freeze can affect bougainvilleas. Here is how to care for frost-bitten plants:
Delay Pruning
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Wait until new growth emerges before pruning damage.
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The extent of injury may not be apparent right away.
Remove Dead Growth
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In early spring, selectively prune out dead wood.
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Cut back to just above live growth buds on stems.
Provide Frost Protection
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Erect barriers, use covers and add lights to shield regrowing tissue.
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New growth is the most vulnerable to cold damage.
Avoid High Nitrogen
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Fertilize with low nitrogen to reduce excessive shoot growth.
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Slow growth acclimatizes plants for dormancy.
Monitor for Pests
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Weakened plants are prone to pests like aphids and mites.
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Use horticultural oil sprays to prevent infestations.
Be Patient
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Recovery takes time. Allow at least 1-2 growing seasons.
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Healthy roots will generate new top growth.
Long-term Protection for Winter
To avoid recurrent frost damage, incorporate these practices into your winter care regimen:
Prune and Shape
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In fall, prune back long shoots and shape growth.
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Remove old flower spikes to promote new blooms.
Prep Container Plants
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Move pots together in a sheltered spot.
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Insulate roots by huddling or burying pots.
Relocate Indoors
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Before frost, transfer plants into an unheated garage or covered patio.
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Provide ample sunlight from a south-facing window.
Remove Debris
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Dispose of fallen leaves, stems and debris under plants.
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Good air circulation reduces disease risk.
Apply Dormant Sprays
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Coat plants with horticultural oil to suppress overwintering pests.
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Spray when plants are dormant, before new growth emerges.
By planning ahead and diligently protecting your Barbara Karst bougainvillea from cold damage, you can continue enjoying its vibrant blooms year after year even in frost-prone areas. With proper care, this tropical show-stopper will thrive season after season.
What is the Lowest Temperature Bougainvillea can Tolerate?
The sweet spot for bougainvillea is above 32F. Anything below that will cause light or extensive damage. Tucson is slightly colder in the winter (USDA zones 9a/9b) than Phoenix (10a/10b) where bougainvillea gets bigger & has a better chance of not being hit.
I’m learning all about this topic with you. I lived in Santa Barbara for 10 years where the winter temps rarely dip below 40F. My 2 bougainvilleas needed a winter pruning to shape and train only. Bougainvilleas are winter marginal here in Tucson but you see them planted all over town regardless.
How Does Bougainvillea Come Back After a Freeze?
It depends on how bad it’s been hit & how & when you pruned it. Mine growing against the house opposite the pink grapefruit tree didn’t get nearly as much damage as my Barbara Karst growing in the driveway area. They have a thinner growth habit & don’t flower as much because the grapefruit tree shades them.
My Barbara Karst looks the same right now (early Nov.) as it did last year. In spring & summer that wasn’t the case. I don’t let it get too tall & keep it pruned as a full shrub rather than a climbing plant. I waited until mid-April to prune it. I could have done it a bit sooner but kept putting it off because other things (life!) got in the way.
If yours is tall & you cut it way back, you’ll most likely get a lot of foliage growth.
HOW TO PROTECT YOUR BOUGAINVILLEA FROM FREEZING TEMPERATURES?
FAQ
Do I need to cover my bougainvillea from frost?
Will bougainvillea come back after a frost?
What to do if bougainvillea freezes?
Are bougainvillea frost sensitive?
How do you care for Barbara karst bougainvillea?
Barbara Karst Bougainvillea is a fast growing plant and may deplete the nutrients in its soil over time. Replenish them with a gentle organic fertilizer or compost every 1-2 months depending on your location and season. Fertilize more often during the growing season and in warmer and brighter climates.
Does Barbara karst bougainvillea need potting soil?
Barbara Karst Bougainvillea does best in well-draining soil. A good soil will contain lots of organic matter such as coco coir as well as perlite or vermiculite to help with drainage. Adding a handful of perlite to regular store-bought potting soil should do the trick!
When to plant Barbara karst bougainvillea?
Choosing the Right Time and Location: The best time to plant your Barbara Karst Bougainvillea is in spring or early summer after the danger of frost has passed. Select a location that receives full sun, ideally at least 6-8 hours of direct sunlight daily. Bougainvillea thrives in warm temperatures. Ensure the planting site has well-draining soil.
Is Barbara karst Bougainvillea a perennial?
Yes, the Barbara Karst Bougainvillea is indeed a perennial, and that’s one of the reasons I love it so much. It comes back year after year with its stunning, vibrant red blooms. It’s a joy to see it flourish through the seasons, especially when many other plants have finished their blooming period.