How Cold Is Too Cold For Flowers To Be Outside?

Many of our most popular garden flowers originated in sub-tropic or tropic environments. That’s what makes them so special to look at but keeping your yard bright and beautiful for as long as possible is every keen gardeners yearly fought battle.

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So how cold is too cold for your flowers to be outside? Many flowers will begin to struggle once the outside temperature drops to 45F; tropical flowers may even begin to wilt before this. Annual flowers are equally sensitive to the changes in the seasons and are typically the first ones to go. While rare, there are some flowers that can survive in almost freezing conditions.

This is a question with a variety of answers.

Why?

Because there are so many different types of flowers, each of which thrives in different climates and environments.

Nevertheless, and generally speaking, once the first frosts set in, your delicate garden-grown flowers will begin to wither.

Finding flowers that have a little more backbone when it comes to incoming frosts can stretch out your garden’s floral season and provide a little bit more color before the bleak winter sets in.

What Flowers Can Withstand The Cold?

Cool-weather hardy flowers can withstand chilly temperatures down to 7c, but frost hardy flowers can survive even lower temperatures.

Adding more robust flowers, whether you go for annuals or perennials, can add months to your garden’s flowering season.

Nature is on our side swell as there are plenty of flowers that can survive outside of the warmer summer months.

Some will even be able to withstand snow and frost – hello winter-blooming flowers.

Below is a list of flowers that are all stunning and can withstand some colder temperatures but will not survive Jack Frosts icy touch:

  • Calendula
  • Osteospermum
  • Petunia
  • Geranium
  • Cyclamen
  • Primrose
  • Sweet Pea

If you’re looking for some more frost tolerant flowers to give you that ‘Spring has Sprung’ feeling in the earlier months of the year, then I have some fabulous flowers that you need to consider.

  • Winter Aconite
  • Pansy
  • Hyacinth
  • Sweet Alyssum
  • Snowdrop
  • Daffodil
  • Crocus
  • Dianthus
  • Dusty miller
  • Snap Dragon

If you are desperate for a bit of winter color, you can go for an evergreen plant.

However, you will be very limited as to what flowers you can plant, but some can be worth seeking out. Such as:

  • Helleborus
  • Winterberry
  • Winter Jasmine
  • Pieris
  • Ornamental Cabbage
  • Winter Heath

Flowers aren’t the only show stopper that you should consider when you are trying to bring more color to your yard for early spring or late autumn.

Edible vegetable plants, like flowering kale or Swiss chard, can bring a tasty but vibrant element to your flower garden.

Swiss chard, especially the rainbow variety, has brightly colored pink, red, and yellow stems that really pop and can grow well into the cool autumn season.

How To Identify Flowers That Will Be Able To Withstand The Cold

The most foolproof way of working out what plants will be able to withstand the cold in your garden is the true and tested method – trial and error.

Luckily, this kind of work has been put in by gardeners and horticulturists that have come before us.

And simply knowing the average temperature fluctuations for where you live can take a lot of the guesswork out of what plants will survive in your garden.

Gardens closer to the coast tend to have milder winters with less threat of heavy snow. However, they don’t have the warmer summers that more inland areas will experience.

Elevation can also be a key player when it comes to temperature fluctuations.

Higher elevation means cooler temperatures.

So you will have to consider this when it comes to your flower choices.

Unfortunately for us, working out what plants will survive your area’s colder months isn’t as easy as just knowing what area you are in and by looking at your desired flowers’ physical characteristics.

Some delicate-looking flowers can be hardier than they look, and similarly, hardy-looking flowers could be as sensitive as your Nana on a cold evening.

Most flowers and seeds that you can pick up from your local gardening center will already have their hardiness level written on their label, along with optimum planting months and even height averages.

Taking a lot of the guesswork and heartache out of the job for regular joes like you and I.

But what if you were gifted a plant and know nothing beyond its name?

Google is your friend, always.

Living in the age of the wonder web has some great advantages.

You can find every little piece of information on your mystery plant you could ever need.

Alternatively, books on flowers are a great place to find information on your flora and fauna if you love the smell of books in your hands.

Once you have worked out how hardy your flowers are when it comes to dipping temperatures, you will then need to decide on how to care for them before the first frosts hit.

One popular method is to grow less hardy varieties in containers and pots.

These are very easy to bring inside before they get damaged or die off, which is another excellent way of extending their flowering period.

Sometimes using a polytunnel air greenhouse to grow flowers in can extend their flowering time.

It’s important to know that greenhouses and polytunnels will experience severe fluctuations in temperature as the winter closes in, so this isn’t a foolproof method unless you are lucky enough to have a heated polytunnel or greenhouse.

If you do, there’s the potential to have year-round flowers blooming, even if they aren’t frost tolerant in the slightest.

Effects Of Cold On Flowers That Cannot Withstand It

The effects of cold on plants are more obvious in plants that are not very hardy or even plants that haven’t been ‘hardened off’ correctly before being subjected to the harsher elements you experience outdoors.

Early signs of cold or frost damage on your flowers can be minute and sometimes difficult to spot before the damage has gone too far and there is no saving the plant.

The easiest to spot early signs of cold or frost damage is wilting leaves.

Some plants will have wilting leaves from over or under watering, but this can be a sign that your plants and flowers are not very happy.

Some more serious signs that your flowers are struggling with the dipping temperatures are:

  • Black Scorch
  • Serious Wilting Collapse
  • Damage to blooms or young fruit

So why does the cold have such a serious effect on a lot of flowers?

It’s time to get on your scientific hat because we are about to deep dive into plant cells so you can understand why the cold can be so life-threatening for many of your prized flowers.

Frosts can cause the water cells in your flowers to freeze.

Much like when you freeze water in a bottle in your home freezer – the water cells of your flowers will expand as they freeze.

Unfortunately, these cell walls aren’t as robust as your water bottle, and they will rupture as they freeze, causing your flowers to die.

It’s pretty morbid and sad, but hey! Like Mufasa told us, ‘It’s the circle of life.

How To Protect Your Flowers In The Cold Weather

Simple tricks like covering them in fleece or planting them in containers so they can be brought in work a treat for many tender flowers.

Knowing the hardiness of your flowers will help you to decide what methods will work and what ones won’t.

Provide Insulation

If you are only expecting a light overnight frost, covering them with a fleece or a blanket can act as insulation.

Helping to keep the air around the flowers warm while you are waiting for the sun to rise.

Be sure to remove all blankets and fleeces first thing in the morning after a cold snap.

If you don’t, the warm air underneath can create condensation, which will then freeze during another cold snap.

Grow In Containers

Growing your flowers in containers gives you the option to bring them inside and out of any frosty weather, but also polytunnel and greenhouse-grown flowers are provided with a little more protection from the cold.

However, don’t rely entirely on the protection of these structures; they can only provide so much extra warmth if they aren’t heated.

Water Early

When watering your flowers, it’s important to only water them early in the day during colder weather.

This gives your plants the chance to fully absorb the water before the temperature drops at night.

Avoiding the foliage can also help protect against frosts.

Consider Mulch

For deeper frosts, you’ll have to employ the heavy guns.

Wood or hay mulch around your plant can help keep the soil temperature up, protecting the plants’ roots.

Even if the leaves and flowers get damaged, many times you’ll find that flowers can grow back if their roots survive.

Leverage Warm Water

For extra protection, you can create extra warmth around your plants by closely placing jugs or bottles of warm water in with the hay mulch to create a radiator-type effect for your plants.

This can help stave off the cold and provide them with more opportunities for their roots to survive.

Finally

Helping our flowers thrive can be a tricky business.

But choosing flowers that are more resistant to the cold and frosts and using every trick in the toolbox when it comes to keeping them warm can result in the most gloriously colorful garden for more months of the year.