Temperatures below 50°F may stunt their growth for a few weeks, and temperatures below 35° may cause some leaf damage. Freezing temperatures will kill the leaves of most houseplants completely, but the roots typically survive if it was only a short exposure.
Covering plant material at temperatures between 39-30 with freeze cloth or covering can be effective. Prolonged exposure at temperatures of 28 degrees and below will notice protection results diminish with each degree dropped.
WHEN TO BRING PLANTS INSIDE. As a general rule, tender plants should be brought in when nighttime temperatures are below 50 to 55 degrees F, even if they are hardy for your zone. A plant's roots are more exposed when planted in a container versus in the ground.
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation. Severe or hard freeze - 25° Fahrenheit and colder causes heavy damage to most plants.
The National Weather Service issues frost advisories when low temperatures are forecasted to be between 33-36°F. Frosts generally cause minor damage but can cause damage to sensitive species, especially flowers and flower buds that have broken dormancy. A freeze is more damaging than a frost.
Seedlings, with their tender new leaves, often give up the ghost when temperatures dip to 32-33°F. Tropical plants have differing low-temperature thresholds. Some keel over when temps fall to 40°F; others crumble at 35°F. Other plants are just hardy by nature and can withstand temperatures as low as 18-20°F.
There is no universal temperature for all plants that is too cold, so that is why it is important to do your research. However, it is safe to say if living in an environment with harsh winters and temperatures below 20°F, it is always wise to bring plants indoors during this time, if possible.
Even though the air needs to be cold, frost can form even when your thermometer is well above 32 degrees. That's because temperature sensors are typically five feet or more above the ground. This includes at-home weather stations, as well as official sensors used by the National Weather Service.
Each plant has a different threshold when it comes to dealing with the cold. Some plants can survive outside even when temperatures hit freezing. Others need to be brought indoors when temperatures reach the mid-40s. Be sure you know this before you plant.
Another temperature to keep in mind: tomato plants will not survive in temperatures below 35 degrees Fahrenheit, and will not thrive at temperatures below 50 degrees. Gardeners can use a frost date calendar to note their region's average dates of last frost in spring and first frost in fall.
So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt.
Spray with Insecticidal Soap: Before bringing your plants indoors, thoroughly spray their leaves, stems, and trunks with insecticidal soap to eliminate any remaining pests. Allow the spray to dry thoroughly before bringing the plants inside.
As soon as the minimum temperature for the plants is reached permanently, they can be moved out of their winter quarter. Mediterranean plants with sturdy leafs such as olive, laurel and oleander can already be put outside in the beginning of April if no permanent frosts are expected any more.
Most peppers are not happy when temperatures drop below 50-60˚ F.
If a low temperature of 29o F is predicted, start with a row cover or frost cover. If temperatures are expected to drop several degrees lower, add a frost blanket or a layer of plastic sheeting over the top that will hold in the air and reflect heat back to the plant and soil.
If you're looking for tips for protecting your plants from frost, avoid using garbage bags as plant covers. Trash bags are not the best protection against frost damage, primarily due to their material. Most garbage bags are made out of low-density polyethylene plastic.
Once temperatures drop below 40°F, you may want to start covering your plants with a frost blanket depending on what you're growing, which we'll get into in just a bit. Freeze – A freeze is when the air temperature is 32°F or below.
There are, of course, many variables that can affect winter hardiness in a plant, but in general, my rule of thumb is as long as the mercury stays in the 20's at night and rises above freezing during the day, our plants should be just fine.
Even if a chill doesn't kill them, it can dramatically slow down their growth. The best time to bring plants inside is when nighttime temperatures start to dip below 55 to 60 degrees F. (12-15 C.). Before bringing container plants indoors, check for pests that may be living in the soil.
near freezing temperatures between 33F-35F…OR… Wind Chill Advisory in effect with lowest wind chills between 29F-35F…OR… flurries (very light snow) with no accumulation. " A Very Low Threat to Life and Property from Excessive Cold."
Freezing occurs when air temperatures are 32°F or colder. Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.
Although water freezes at 32 degrees F, road surface can freeze when the air temperature drops to 40 degrees or less. bridges.
When do I know it's safe to bring my plant outside? It's safe to move your plants outside when the outdoor temperatures stay consistently above 50°F. Pay attention to the weather report. If nighttime temperatures are set to fall below 50°F, bring your plants in for the night.
Thoroughly Water plants if it won't rain before the freezing temperatures arrive. It may sound illogical. However, the moist ground stays warmer than dry soil. Watering the night before the freeze will insulate the grass and plants' root structure and decrease the potential for cold injury.
Between 32 and 29 degrees
The temperatures in a light freeze will likely kill them. A light freeze takes place between 32 and 29 degrees. If you're catching your local weather report, you'll hear your weather forecasters call this a “freeze warning.”