When Tulips appear out of the soil, it’s the sign that winter is almost over and spring is nearly here.
This means most gardeners can’t wait to see these harbingers of spring. But, if you’re new to growing Tulips or live in a warmer climate, you might be wondering about frost and what kind of cold temperatures it can withstand.
It’s always best to keep in mind the original, native habitat for Tulips to ensure they receive similar conditions. Remember, they come from areas of the world where dry, hot summers occur after very cold winters like Siberia, China, and Mongolia.
What Kind of Temperatures Kill Tulips?
Spring Tulips is one out of a few handfuls of plants that can tolerate cold temperatures. Winter temps in colder climates don’t usually reach less than 30 degrees Fahrenheit below the surface unless a deep freeze happens.
This means the bulb retains heat and stays fairly protected in the soil because they only sit two to six inches deep.
Therefore, the ideal temperature range for Tulip bulbs is between 35 degrees and 55 degrees. Anything below or above will cause the plant to suffer for various reasons. This is why the U.S. Department of Agriculture suggests zones between 3 and 8 for growing Tulips.
30 Degrees Fahrenheit or Less
Anything below 29 degrees Fahrenheit is getting dangerously close to killing the tulips.
So, if they start coming out of the ground and a spring freeze drops temps below 20 degrees, the plant has the potential to die. That said, if it gets between 20 and 25 degrees, although struggling, it should be fine.
For example, 19 degrees is cutting it close, but the flower should survive. However, if a bud freezes, it’s likely the flower won’t bloom.
If it’s going to drop into single digits, you should cover them with a tarp or mesh fabric to keep them warm. If you’re unable to protect the flowers with some sort of thermal covering, any part that’s frozen will sustain damage.
Too Warm Too Soon
Until flowers appear, it’s important that bulbs stay at 40 degrees Fahrenheit or less. It can tolerate 55 degrees, but less is better.
The bulbs do not like warmth from the direct, hot sun. Only when flowers burgeon from the soil is the Tulip okay to handle warmer weather. They will grow at around 60 degrees with flowers and leaves appearing at around 68 degrees.
What is the Coldest Calefaction that Tulips Need?
Tulip bulbs, in order to bloom, must reach a temperature of at least 40 degrees Fahrenheit or colder. They have to remain this way for 10 to 12 weeks on average. Some gardeners say they can have as little as eight weeks or as much as 15 weeks.
U.S. Department of Agriculture Hardiness Zones
For people who live in warmer climates above the USDA hardiness zone of 8, it’s advisable to store bulbs in the refrigerator. Keep them in a paper bag until December, when the soil reaches 60 degrees in late winter.
Will Tulips Withstand Freezes?
Tulips can withstand a freeze and do well in cold weather. But, if the range of temperature is going to be lower than 20 to 25 degrees Fahrenheit, the plant may struggle but the bulbs won’t.
However, there are some people who report experiencing a quick, hard freeze as cold as 14 degrees and have the flowers turn out fine.
So, this has more to do with the specific variety of Tulip you have. There are some types that can withstand much colder temperatures than is normal for most Tulips. Yet, there are others that are very sensitive to temperatures at 32 degrees or less.
Do 32 Degrees Freeze Tulips?
Tulips will freeze at 32 degrees Fahrenheit, but they should still be good and hardy. When temperatures get well below 29 degrees, you run the risk of killing the whole plant altogether; stems, leaves, and flowers.
A Note about Spring Bulbs
Unfortunately, dormancy will set in if a Tulip’s foliage dies off too quickly after flowering. It’s also very unlikely that flowers will appear the following year. But, Tulip bulbs need this kind of temperature while in the soil.
This is because of the sugars inside the Tulip bulbs. They counteract frost in the same way as when we put salt on a sidewalk in winter.
Because of the precise and picky temperature requirements of Tulips, many people think they’re too difficult.
As long as you can provide the ideal temperature range between 35 and 55 degrees for about two months with well-draining soil, the Tulips will thrive well and be beautiful in spring. If you can recreate their native habitat with very cold winters that follow arid summers, they are rather easy to grow.