Will 36 Degrees Fahrenheit Hurt Your Plant?

Sudden cold spells can’t be helped when you live in the northern hemisphere. Especially when the thermometer hits the 36-degree mark and frost may or may not appear. But will this low temperature hurt your plants?

As a general rule, 36 degrees Fahrenheit (2° Celsius) will not hurt cold-hardy plants. However, tropical, subtropical, and young plants will likely suffer cold damage. It is better to cover & secure all plants with burlap or fleece to prevent frost as a precaution.

If your plant was exposed to too cold of a temperature, check out our article: How to Best Warm Up a Plant Exposed to Cold Temperatures

And even if your plants are good ok outside, your pots might not be, let me save you from hours of super gluing your ceramic and terra cotta pots back together –> Can I Leave Pots With Soil Outside In Winter? Here’s What You Need to Know

Below, I elaborate more on this with tips on how to minimize plant losses:

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What is the Range of Cold Temperature That is Dangerous to Plants? 

Note: Hardiness zone is based on the estimated lowest temperature a plant can tolerate before it gets cold damage. Here we provided a range to show what may be considered Tropical/Subtropical v.s. Temperate. This is by no means a strict guideline to follow and hardiness zones do overlap what is considered Tropical and Temperate climates. 

Hardiness zones are more accurate and are determined by the annual minimum temperatures an area experiences each year. The exact lowest temperature can vary year to year but the variance in temperature usually isn’t a problem for the plants listed in the hardiness zone. Please do a quick search on our site (top right corner) or a search engine to find the hardiness zone for the most accurate acceptable temperature range. If you aren’t sure what the name of your plant is, use a tool like Google’s “lens” or image search and identify the plant first.

The hardiness zone and the low temperature in your area aren’t bans from growing plants that aren’t fit to be outside! It does put the tropical and subtropical plants in colder regions at a higher risk of struggling and bouncing back from cold damage. If you ever find yourself wondering why your banana plant didn’t survive a sudden dip to 36°F despite covering them up to prevent frost, the cold temperature is the main reason. That being said, for smaller plants simply bringing them inside in the cold months will allow you to keep plants that belong in a totally different hardiness zone.

Temperate plants have a better chance of bouncing back despite getting cold damage. This is thanks to their natural defense mechanisms to survive frigid weather. But that does not mean they are invincible. They certainly won’t survive in hardiness zones 1-4 (-60 to -20°F), unless they are native plants. When in doubt, all tropical and subtropical plants are the most delicate in cold weather.

If your plant is inside your house and wasn’t exposed to the cold but looks kinda dead, check to see if your plant is just in a dormant period, it might just be sleeping. Some plants like the Oxalis Triangularis “hibernate” for a bit each year and appear, well… dead-looking. But, in the case of the Oxalis, it comes right back to life a few months later.

Will 36 Degrees Fahrenheit Kill Plants? 

As mentioned in the introduction, cold-sensitive and tender plants such as tropical ones are the likeliest to suffer or die at 36°F (2° C). Unlike cold-hardy or cold-tolerant plants, they cannot protect themselves against nippy temperatures. However, some tender temperate plants may also struggle because of frost.

Frost can occur anywhere from 32-40°F (0-4° C) when the skies are calm and cloudless. The risky thing about frost is that it can cause water in plant cells to freeze, expand and destroy the cell walls. It may not be as instantaneously harmful as freeze damage but repeated, and prolonged exposure will kill even the hardiest of plants.

With that said, DO NOT spray off frost from your plants. I wrote a whole article on this method on why it does more harm than good on your plants.

Here are a few related questions that may be useful to you:

Can plants survive 35 degrees Fahrenheit? The short answer is yes, provided they are not tropical or sub-tropical plants. Cold-hardy plants are likely to thrive and manage with some light frost in this temperature. 

Should I cover my plants at 36 degrees? As a whole, all tender plants should be brought indoors or protected with garden fabric to prevent frost when it is 36°F outside. For cold-hardy plants, this is entirely optional. But it’s better to err on the side of caution when the temperature falls below 40°F. Most ornamentals won’t like it when the frost gets on their blooms and foliage, but some edible crops won’t mind a light frost at all. 

Can it frost at 36 degrees? The short answer is yes! Frost is not entirely determined by air temperature, which is why it can occur even above the freezing point, i.e. (32°F/0°C). Frost is likely when there are clear skies with no wind in sight and falling temperatures in the afternoon.

How to Minimize Plant Losses When The Temperature Drops?

1. Cover plants with garden fabric like fleece or burlap before night falls.

(Note: The following links provided are Amazon links.)

Seriously, always have woven fabric on hand tucked away in dry and cool storage. Even if you don’t have them, use sheets or blankets instead. As long as they are covered, frost can’t get on your plants at all. Just make sure to remove the coverings in the morning to let your plants get some sun and airflow.

Potted plants are more susceptible to cold damage because they are not planted in the ground where heat is retained in the soil. Cover the top with sheets with a thick layer of burlap around the pot to help keep the roots warm. You could also always bring them indoors to make things easier.

2. Water the soil deeply before the predicted frost.

Water can create a microclimate around the plant even as the temperature drop further at night. Just ensure there isn’t any splashback to the plant’s foliage when you water them, as that will worsen things. This applies to both in-ground and potted plants. For the latter, be careful to drain excess water completely after watering. 

3. Don’t prune off cold-damaged parts of the plants.

Unless the damage has spread to ¾ of the plant, it’s better to leave these parts alone for now. Believe it or not, this helps insulate the plant from further harm. Not only that, you prevent unnecessary early growth from the trimmed parts. Remember that the plant is already struggling in the cold weather; forcing it to grow will only be detrimental to its health.

Once the last frost has passed, you can start pruning your plants. Depending on your hardiness zones, this can be in spring or summer. When the temperature warms up, the plant will likely show the damage it has sustained from fall or winter. This is another reason why it’s better to wait to trim – you can see how extensive the damage is and whether the plant can recover.

Final Word

All in all, keep your tropical and subtropical plant babies cozied up and warm, far away from the cold depths of 36°F. But let your hardier plants have fun in some light snow. Happy planting!

References:

https://pender.ces.ncsu.edu/2022/02/up-and-down-temperatures-tough-on-plants/

https://lenoir.ces.ncsu.edu/2017/01/will-the-cold-temperatures-damage-my-plants/

https://hgic.clemson.edu/factsheet/cold-damage/

https://wrcc.dri.edu/Climate/Education/freeze_frost.php

https://www.extension.purdue.edu/extmedia/HO/HO-203.html

https://extension.umd.edu/resource/winter-damage-landscape-plants

https://extension.msstate.edu/publications/protecting-plants-cold-temperatures

https://nwdistrict.ifas.ufl.edu/hort/2014/01/20/cold-damaged-plant-care/

https://www.canr.msu.edu/news/symptoms-and-consequences-of-chilling-or-freezing-injury-on-greenhouse-crops

https://secure.caes.uga.edu/extension/publications/files/pdf/B%201467_1.PDF

https://extension.psu.edu/frost-critical-temperatures-and-frost-protection

https://www.canr.msu.edu/news/what_is_the_difference_between_a_frost_and_a_freeze