Why Do Plants Need Warmth: Save Your Plants From Temperature Stress

We love our plants. Plants are precious whether you have a thriving outdoor garden or a green living room corner. All the steps you take to nurture them and protect them from harsh weather is crucial. Ensure your plants are nice and cozy, especially during winters, and take action before the nasty frost gets to them. But why do plants need warmth, and how can you save your plants from freezing this winter?

Continue reading, and you’ll find out everything you need to keep your plants protected from the cold!

Why Do Plants Need Warmth?

Because they are living things, plants need warmth, but they also need protection from the cold weather. While we humans can hide under layers of clothing to stay warm, plants can’t. Giving them frost blankets is a good idea to keep them comfortable, but we’ll discuss it later.

So anyways, both soil temperature and surrounding temperature matter when it comes to healthy growth. Here are some reasons why most of your plants like it warm:

  • Nutrient absorption is high when plants are warm.
  • Warmth speeds up photosynthesis in plants and catalyzes respiration while enhancing its rate.
  • For different plant varieties, there’s a minimum temperature that seeds need to germinate. The speed of germination increases with the increase in temperature until it reaches the optimal point.
  • Most indoor plants are native to the tropics, where the temperatures are usually higher. Many of these plants won’t survive in low temperatures.

Temperature is, in fact, one of the reasons why different plants are suited for different growing zones. Therefore, it’s essential to check the plant’s hardiness before planting something and decide whether it will work in your growing zone.

Ideal Temperatures For Seed Germination

Seed germination isn’t possible at low temperatures. Similarly, germination starts to decline once the temperature rises above the optimal level. Therefore, it would be best to know the ideal germination temperatures to ensure that the seeds sprout.

What Are Cool-season Plants?

Cool-season plants, like potatoes, broccoli, and lettuce, will germinate optimally at temperatures falling in the range of 55 to 70ºF (about 13 to 21ºC).

What Are Warm-season Plants?

Warm-season plants, including marigolds, corn, and cucumbers, will germinate best at temperatures between 70 to 85ºF (about 21 to 30ºC).

What Does Cold Damage Look Like On Plants?

Plants are generally quite expressive in showing what they’re feeling. If it’s too cold for them, here’s how they’ll show it:

  • Splits in stems
  • Loose root balls
  • Blackened leaves
  • Unnatural shedding of leaves
  • Wilting or drooping their leaves
  • Burn spots on flowers and leaves

All the symptoms above suggest that your plants are stressed from low temperatures. Make sure you take the necessary steps to reverse the damage and help your plants survive the cold by giving your plants enough warmth.

How To Measure Soil Temperature?

Measuring soil temperature isn’t that hard. Most vegetable gardeners use a soil thermometer to keep the soil temperatures in check. These devices help them to maintain the optimal conditions for their crop. The thermometer is attached to a long metal probe pushed into the soil to take its temperature.

If you’re sowing seeds, you need to push the thermometer 1 to 3 inches (about 2.5 to 7.5 cm) deep, while for transplanting, go about 5 inches (about 12.5 cm) deep. Leave the thermometer in the soil for a couple of minutes before taking the reading.

What Time Of Day Should You Measure Soil Temperature?

Soil temperature fluctuates with the weather each day and changes with the time of the day. So, it’s best to take the reading early in the morning since you’ll find your ground the coolest. Also, test the temperature reading for three to four consecutive days and find the average for a reliable estimate.

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How To Raise Soil Temperature?

Here are some ways to make sure the soil is warm enough for your plants:

  • Raised beds are usually warmer than the ground.
  • Avoid shady areas, especially for warm-season plants.
  • Using black containers to grow plants can raise the temperature over 5ºF (about 3ºC) compared to the soil in your garden!
  • South-facing gardens, and if you’re growing indoors, windows are ideal for most plants as they get plenty of sunlight to keep the soil warm.
  • Mulching helps preserve the soil’s temperatures. A plastic sheet that’s lightly tinted black helps the soil absorb the sun’s heat and prevents it from radiating out when night falls.
  • Warm-season plants will be happier indoors if you plant them in winter. You can start them indoors and transplant the seedlings outside once the threat of frost subsides.
  • Cover the planters with a frost blanket, especially if there’s a prediction of frost. It’s a lightweight material that keeps the heat from radiating out of the soil. And best of all, they’ll also protect your plants from pests!

Ideal Temperatures For Your Plants

The tropical plants you have around your home are susceptible to the cold. So please make sure they’re in a cozy corner for the winters so they can grow well.

Most leafy houseplants thrive in temperatures between 65 – 75ºF (about 18 – 24ºC) during the day and 60 – 67ºF (about 15.5 – 19.5ºC) during the night. Flowering varieties will thrive in the same daytime temperatures but like a bit cooler night temperature, between 55 to 60ºF (about 13 to 15.5ºC).

Keeping your plants at a temperature like these is quite simple indoors since we humans also find the same warmth comfortable. The simple rule of thumb is:

When You Feel Yourself Comfortable, Your Plants Are As Well.

If you’re growing indoors, and the plants are in one of the rooms with heating systems, they’ll have the ideal temperatures. However, make sure that they’re not sitting next to any radiators or air conditioners.

Sudden temperature changes are especially problematic for your indoor plants. A sudden temperature drop of more than 10ºF (about 5ºC) can create growth problems and even kill the plant in the worst-case scenario.

Read our post – Indoor Gardening In Winter (4 Simple Things To Keep In Mind) – to learn how to care for houseplants in winter.

How To Keep Your plants Warm Through The Winters

Most houseplants can’t withstand the freezing winter temperatures. While they’re much better off indoors than your garden plants during the frost, you can take some extra steps to make sure they’re comfy:

Draught-proof Your Windows

Windowsills are the best spots for indoor plants during the summers because of the adequate light and warmth. But, cold drafts in the winters aren’t suitable for the plants. So, remember to draught-proof your windows if you haven’t already. Moving them a little bit further could also prevent some of the damage.

Turn Up The Heat

If you haven’t already, turn on the radiators and maintain warm surroundings for the plants. Make sure they’re not too close to the heaters.

Heating Mat

Most gardeners place seedlings tray over a heating mat to speed up germination. Your shivering houseplants will also like it better when sitting over a heating mat. If you want to get yourself one, you can get one from Amazon! ➔ Just to let you know, that is an affiliate link!

Place Them Over The Fridge

If you don’t have a heating mat, the fridge’s top is a warm spot to sprout your seeds. You can also place a few lightweight potted plants there to keep them warm. Be careful while watering these plants; you wouldn’t want to spill it around electrical equipment. Plants don’t get too thirsty during the winter months anyway, which means you can skip a watering or two.

Heat lamps

Install plant-friendly heat lamps over your plants. The warm glow won’t only keep your plants comfy, but they are also a beneficial light source to boost photosynthesis.

Some Plants Like It Cool!

Some plants are well adapted to freezing temperatures. If you want to create a beautiful winter landscape outdoors or search for houseplants that can survive the winters, here are some suggestions:

  • Peony (Zone 3)
  • Sedum (Zone 4)
  • Pansies (Zone 4)
  • Siberian Iris (Zone 3)
  • Winterberries (Zone 2)
  • Primrose (Zones 3 To 8)
  • Coral Bells (Zones 3 To 9)
  • Coneflower (Zones 3 And 4)

Final Words

Whether growing your plants indoors or outdoors, winters are challenging for most plants. But, you already have the answer to why do plants need warmth. All their fundamental activities are hindered if the temperatures are below the optimal levels. As long as their surroundings are warm, they’ll germinate on time, absorb nutrients, and perform photosynthesis optimally.

If you want to start your warm-season crops, such as tomatoes, before the spring, it’s always good to start them indoors, where it’s easier to keep them warm. Then, transplant them into the garden once the threat of frost has passed. Please take into account the soil’s temperature and then decide whether it’s suitable for planting or not.

Featured image credit – © lassedesignen – stock.adobe.com

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