The best way to protect your blueberry bush from cold temperatures is to provide shelter against the cold. Wrap or cover blueberries to provide warm temperatures. It’s also essential to keep the soil moist and add small heat sources to protect your blueberry bushes. Frost damage most often occurs during cold nights, so that is when your blueberries need the most protection. Just be sure to refrain from implementing heavy-duty frost protection until temperatures drop below 20°F (-7℃).
Will Frost Hurt Your Blueberry Bushes?
Frost can hurt your blueberries but the temperatures have to be very cold to cause lasting damage. Blueberry plants are more resistant to cold damage than many fruit crops. They won’t start experiencing damage until it’s under 28°F (-2℃).
- Blueberry bushes are hardy and won’t get frost damage until 28°F.
- Protection is needed for blueberries to survive anything below 20°F (-7℃).
Dormant blueberry plants have been known to survive temperatures as low as -30 degrees Fahrenheit (-34℃). However, you don’t want to just trust that your plants will survive late winter without help. Proper care of blueberries is needed to keep them safe in frosty conditions and ensure your bush lives a full life.
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When Should You Cover Blueberry Bushes?
Once weather conditions are consistently below 20°F (-7℃), it’s time to cover your blueberry bushes. A weather shelter of propylene, burlap, or even old blankets will help prevent heat loss and cold injury.
- Cover your blueberry bushes when temperatures stay consistently below 20°F (-7℃).
- Try to avoid covering your blueberries for most of the day.
Be sure to cover your bushes as little as possible during the day. Even transparent weather covers will reduce the sunlight that reaches your plants. This can interfere with your plant’s ability to photosynthesize, in addition to having other detrimental effects. It can also keep out warmer day temperatures, which your plant needs in cold conditions.
What Do You Cover Blueberry Bushes With?
Anything warm and thick can be used as a covering for blueberries in a pinch. Anything from burlap to blankets can be employed if there’s an urgent need. You may not want to use blankets or sheets more than a few times though as they can risk getting ruined.
- Burlap, blankets, sheets, or propylene all make decent covers.
- Propylene is the most highly recommended cover and can be reused safely each year.
Some covers are definitely better than others. Propylene covers are the most highly recommended. Use this propylene garden plant cover to protect your blueberries from freezing air temperatures.
- Winter protection for your plants and crops.
- Lightweight and breathable material.
- Can also be used to encourage rapid seedling growth.
How Do You Wrap a Blueberry Bush to Protect it From Frost?
Gently drape the sheet or cover over your blueberry rows in the late afternoon. Doing it at this time will trap in the most heat possible for the overnight period. There are two different ways to secure the wrap. First, you can use a pre-built frame that the sheet attaches to. Sealing with velcro, zippers, or the like will provide a free-standing, stable structure.
- You can attach plant covers to pre-built frames to keep them in place.
- Drape the covers over the plant and weigh them to the ground with wood boards or bricks.
The other way to secure a covering over your blueberries is to let the covering lie on the ground and then hold down the edges with weights. This will get your covering dirtier faster but is a little more cost-effective. Just make sure your weights are heavy enough to hold down the covering even in strong winds.
6 Ways to Keep Blueberry Bushes Safe From Frost
There are many ways to save your blueberries from harsh winter chills. Everything from when you water and your water application rate can help. We’ll break down which methods are the most helpful as well as evaluate how cost-effective each solution is.
Proper watering is one of the best ways to protect your plant. The best time to water is during the day when temperatures are above freezing. Overhead irrigation systems will help a great deal with maintaining soil moisture. Some watering systems can even be programmed to sense critical temperatures. This is admittedly very expensive but it is a worthwhile expense if you’re a serious berry grower.
- Moist soil helps prevent frost damage by providing greater heat transference.
- Use an overhead irrigation system for best results.
Counterintuitively, moist soil is more resistant to frost than either wet soil or dry soil. This is because moist soil is not wet enough to freeze into ice but is wet enough to conduct heat better than dry dirt. Ensuring the right soil moisture will be made easier with a timed irrigation system.
Mulch can act as additional insulation for blueberry plants in cold weather. This is a cost-effective way of insulating your bushes since mulch is fairly cheap. Keeping heat trapped in the soil prevents frost and ice damage from killing blueberry roots.
- Mulch provides effective soil insulation in cold weather.
- It also prevents weeds and offshoots (which can freeze more easily) from growing.
The downside of mulch is that it can only protect the soil level of your bush. Anything above soil level (most of the bush) will still be susceptible to freeze damage. The upside is that mulch also prevents weeds and new offshoots from growing. This is good because they are more susceptible to frost damage and can help frost spread to your bush more easily.
Cover Blueberries at Night
You can reduce frost damage to blueberry plants by covering them with a cold-resistant tarp or sheet at night. Tarps are more resistant to the cold but can’t be used during the day without blocking out sunlight.
- Cover blueberries during the night to trap warm air near the bushes and block cold wind.
- Blueberries still need sunlight and most coverings will block solar radiation.
- Keep your blueberries uncovered as much as possible during the day so they get the most sunlight.
Plastic sheets provide decent protection and can potentially be left on during the day if transparent enough. Both will help prevent severe freeze damage if used correctly. This is a fairly cost-effective solution since the sheets can be reused year after year.
Add a Heat Source
Providing heat, especially in combination with a cover, is a great way to ward off cold. Simply place a heat source under the cover with your blueberry bush at night to prevent freezing. There are many types of heat sources that can be employed to warm your plants. Heat lamps, heat mats, and even jugs of hot water left under the covering will all radiate heat and prevent frost.
- Place a gentle heat source under the cover, near your blueberry plant.
- Heat lamps and heat mats can be used to warm your plants.
- A jug of heated water can be left under each plant covering to provide radiant heat all night.
Heat lamps and then heat mats will be the most effective but they can be fairly expensive and require constant power. Heated water is significantly cheaper but not nearly as effective. Experiment with these different types of heat to see which works best for you.
Use Wind Machines
A wind machine can help circulate air, thus increasing warmth and preventing warm air from cooling off quicker. Ideally, this would be used in concert with a heat source listed above. If you circulate air without heating it, that may slightly warm the air but it is more likely to have little lasting effect. This can be a pretty expensive solution due to the cost of the machine and the constant power use. As such, you might not want to employ it unless you’re sure it’s absolutely necessary.
Don’t Fertilize After August
Stop fertilizing your blueberries by fall to reduce the number of shoots that grow in off-seasons. New shoots are more susceptible to the cold than mature shoots. If enough of them freeze, it can harm the whole bush.
- Do not fertilize blueberries during fall.
- Fertilizing late in the year encourages new offshoots just before winter.
- Young offshoots are more susceptible to frost—if they freeze it can damage the entire plant.
By taking steps to discourage new growth before winter, you will protect the entire plant. This is by far the cheapest solution since all it takes is not doing something. If you have fertilizer, don’t use it from September until spring.
Will Frost Harm Blueberry Blossoms?
A late spring frost can kill blueberry flower bud growth. This will lead to a decrease in fruit development and can even kill off your entire blueberry crop. You don’t have to worry about frost-killing flowers in winter since blueberry plants don’t bud then. However, your flowers won’t bud at all if the plants die from frost. So, protect your blueberries in winter to make sure they flower again in spring.
How Do You Protect Blueberries from Frost?
Protecting blueberries from frost is important and takes careful planning. Remember these tricks to helping your blueberries make it through a freezing winter:
- Keep your blueberry soil moist through overhead irrigation
- Insulate your soil with mulch
- Don’t fertilize your plants after August
- Cover your blueberry crop when temperatures drop below 20°F (-7℃)
- Add a heat source to counteract the chills
- Use a wind machine to keep warm air circulating
With these tips in mind, your blueberries stand the best chance of making it through winter in good health. Blueberries may be hardy, but they won’t survive the winter unless you give them a helping hand.