Will Plants Die In 40 Degree Weather?

Different plants will thrive in very different weather conditions and temperatures. Most common outdoor yard plants will prefer warmer temperatures and direct sunlight.

Plants that are best suited to colder temperatures, including climates that dip to and below 40 degrees (Fahrenheit), are hardy plants. 

Will Plants Die In 40 Degree Weather?

Common hardy plants for your yard include:

  • Siberian Iris - this hardy plant, native to Turkey and Russia, blooms in the spring to produce a beautiful yellow, purple or blue flower but can easily handle the frosty winters in colder climates
  • Sedum - while Sedum is more commonly used as walkable due to their sturdy nature and low growth height it actually comes in a few varieties including one that can grow a little taller making them great additions to your yard, especially because they can handle both the cold and heat
  • Peony - these gorgeous yellow flowers are great for surviving harsh, freezing winters and require very little maintenance
  • Bee Balm - friends of the bees, this pretty pink flower can thrive in cooler temperatures such as 40 degree weather 

You can also purchase half-hardy plants such as French Marigolds that can live in areas where temperatures can reach a minimum of 40 degrees (Fahrenheit) and can even still survive light frost.

Plants that are likely to die in 40 degree weather are ‘tender’ plants. These plants are extremely vulnerable to even light frost and will require added protection in order to survive a drop in temperature.

When should you cover plants at night?

Covering your plants a night is a great way to protect them from freezing overnight temperatures that could cause them to freeze. 

If freezing temperatures are predicted, you should cover your plants before sunset in order to maintain some of the ground heat which will help to keep your plants warm overnight.

Once temperatures have risen above freezing the next day, you can take the cover off to let  the sunlight get back to work.

Will one night of frost kill my plants?

Frost can ruin your lovely garden overnight if your plants are of the ‘tender’ variety. Tender plants are sensitive to cold temperatures and frost and cannot thrive in these conditions. Some examples of tender plants include tomatoes, peppers, avocados, cherry trees and more.

While a frosty night can cause damage to your plants, it doesn’t necessarily mean that your plants will die after just one night of frost.

Can plants recover from cold shock?

Tender plants are vulnerable to sudden drops in temperature and, if you don’t know how to protect/revive them, there’s a good chance they could die. But, if you know what you’re doing, there’s no reason why your tender plants shouldn’t be able to recover from cold shock.

The first thing you need to know, is what cold damage looks like in tender plants. Most tender plants will display one or more of the following symptoms:

  • Drooping - smaller branches and leaves will appear wilted
  • Loose roots - cold damage can often manifest in the roots and can result in very loose root balls
  • Splits - for plants with trunks or woody-like stems, cold damage can cause splitting 
  • Burns - tender flowers and foliage can appear to develop burn-like spots after a cold shock

The time is takes for a plant to display signs of cold damage for up to one to two weeks or more depending on how cold it was.

So, what next? It can be tempting to prune away the dead parts of your plants but when it comes to cold shock it is a good idea to leave the damages leaves or branches as they can act as a protective layer for the healthier parts of the plant until the warmer weather returns and your plants are no longer at risk of further cold damage.

Check the roots too. If your plants roots feel firm, that is a very good sign and the chances of your plant recovering from cold damage is increased significantly.

If the root balls are very loose, the damage done is likely too severe, and it is very unlikely that the plant will recover or be able to support new growth.

Once your plants are showing sign or regrowth, it’s time to start watering them again. This may seem silly, but water will actually help your plants recover from the stress of freezing temperatures.

This is because frozen plants actually lose moisture from their tissues, so watering them (in moderation) will help them to rehydrate.

How to protect your plants from frost?

The best way to ensure your plants will be able to survive cold temperatures is by planting cold-hardy plants. If you’re unfamiliar with these types of plants, put simply, cold-hardy plants are able to thrive despite a drop in temperature and can even withstand short-term freezing.

Some examples of cold-hardy plants include crocuses, tulips, and pansies, as well as cabbage and radish.

You should also take into account your zone to find the plants that will best suit your climate but don’t stress, most plants will be labelled to help you, or you can always ask store owners for advice.

If your plants are ‘tender’, the best way to protect them from frost is to cover them overnight. You can use household materials such as blankets or bedsheets you can purchase frost blankets of various weights from certain stores. These will provide varying degrees of protection from frost.

Alternatively, you can use row covers which work in the same way, but their built-in pores allow more light and air to cut through. These enable you to leave your plants covered for much longer.

What’s great about them is that they let in up to 95% of light while still keeping out pests like caterpillars and birds as well as the frost.

If you have potted plants at risk of the frost, you could consider bringing them indoors if there is frost predicted to protect them from freezing over and simply replace them in the morning.