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Will Frost Hurt Hostas?

Mother nature can be very harsh, and sometimes it seems that winter is over. However, late frosts suddenly return, and for some plants, it may not end well. So you need to be prepared for this situation and know what to do.

Frost can hurt hostas if they start to grow. This often happens with late spring frosts. The leaves may be partially damaged or wither completely.

If the hosta has not yet formed the leaves and only young shoots have emerged from the ground, the damage will be minimal. Hostas that are dormant are not afraid of frost at all. They can withstand up to -40 ° F if there is a thick layer of snow above them.

However, if the foliage has already unfolded, it will definitely freeze. The amount of damage depends on many factors, such as variety, next we’ll talk about it in more detail. I will also tell you what can be done to avoid frostbite and what to do to reduce the consequences.

Will Frost Hurt Hostas?

Does frost kill hostas?

In general, frost will not destroy hostas. This is a very hardy plant and can withstand severe frosts in hibernation. Even in spring, late frosts will not be fatal, the plant will lose some foliage (or all), but the rhizome will remain alive. After a while, the hostas will recover.

However, there is a risk of crown rot. If the frost was severe and the plant was seriously damaged, it may begin to rot the crown. This is quite serious and can lead to plant loss. Therefore, if late frost occurs and there is high humidity, be vigilant and watch the hostas to detect the disease in time and cure them with fungicide.

What temperature can hostas tolerate?

Temperatures of 32 ° F (0 ° C) and below can damage the hosta leaves. If there was a strong wind, the plants would definitely be damaged.

Some varieties can tolerate slightly lower temperatures (28 ° F), such as hostas with hard leaves. It also matters how long the frost lasted. If it was a few hours, then the plants may not get serious damage. If the frost was all night and repeated the next night, the damage would be significant.

Usually, the young leaves are very tender, and even a slight frost will leave its mark on them.

You need to cover hostas from frost

The first thing you can do to protect hostas from frost is to cover them. Covering the plants, you form an air cushion over them that will protect them from frost. Under fabric, the air will heat up from the ground and move upwards, so there will always be a suitable temperature around the leaves.

It often happens that frosts occur before the leaves have unfolded, but young shoots have already appeared. In this case, you should bury them with compost so that they are not visible. Under such a cover, they will survive. Here it is important to use good clean compost so as not to harm the plants. Also, after frost, remove all compost from the shoots to avoid rotting.

If the foliage has already opened, covering the plants is the right thing to do. The heavy anti-frost row cover is best for this. This is a special fabric that is used in the cultivation of plants and protects them from adverse weather conditions.

Before covering, you should create a frame over the plants. As I wrote above, between the leaves and the fabric should be a layer of air. If the leaves touch the fabric, frost can damage them.

Just insert a stick higher than the plant into the ground near each bush. Next, put the garden fabric on top. Put stones (or something heavy) on the edge of the cover to press it to the ground, the stones will not let the windbreak it. You can also fix it with pegs.

When should I cover my hostas?

Hosta is a very hardy plant, so it does not need to be covered for the winter. The only time this may be needed is spring. Depending on which hardiness zone you are in, late frosts can occur at different times.

Below you can see a table showing the date until which late frosts can occur in each climate zone where hostas can grow. A map of the winter hardiness zones can be found here.

USDA Zone Spring frost
Zone 3 May 15
Zone 4 May 15-20
Zone 5 April 15
Zone 6 April 10-15
Zone 7 April 15
Zone 8 Marth 30

As can be seen from the table, the farther north, the later frosts can occur. In rare cases, frosts occurred in early summer.

Every year everything happens differently, so you should check the weather forecast, especially in the spring. If weather forecasters report a drop in temperature to 32 ° F (0 ° C), then you should not risk and cover your hostas. Even if the forecast was wrong and there was no frost, you will not lose anything.

When should you uncover hostas?

Hostas should not be uncovered immediately, as frosts may recur. Remove the cover during the day when it is warm, cover again at night. Then watch the weather for a few days. If the temperature does not fall below the critical level, then you can remove the cover completely.

Other ways to avoid frostbite

There are other ways you can avoid damaging your hostas with frost. The first is if the hostas grow in pots, you should move them indoors. It does not have to be a heated room, a garage or a basement is perfect for this.

Some gardeners use water sprayers to avoid frostbite. They turn on the watering at night, and the water slightly heats the space around the plants. As a result, hostas suffer less.

Will hostas come back after a freeze?

In most cases, the hosta will recover from damage caused by frost, although there may be exceptions.

It often happens that frost damages only the leaves, sometimes even a single leaf is not completely damaged. Therefore, the plants, after a while, will be fine.

For vigorous varieties and for hostas that have already grown a large rhizome, the recovery process will be fast. A few weeks, maybe a month, and new leaves will appear. Of course, the plant will not look the same as if there were no frostbite, but in general, everything will be ok.

For medium varieties and hostas that do not yet have a large size, the recovery may be delayed for the entire season. The plant will look good only in late summer. It may also be that new leaves will not appear. New growth will begin only next spring. You should not worry about this; hostas are living organisms that need time to recover.

The most threatening late frosts are for dwarf varieties. They usually have a tiny crown, and frost damage can be fatal. They can freeze not only the leaves but also the stems and even the rhizome. Therefore, you should take care of them first. Due to their compact size, they can be easily hidden from low temperatures, such as under a plastic container or box.

What to do with damaged tissue?

If your plants have been damaged by frost, do not rush to prune them because you can remove the undamaged part of the plant. The leaves can first wither and then recover without signs of damage. If you prune all the leaves at once, then next year, the hosta will lag behind in growth, and the leaves will be small.

Wait a week or two and watch the plant. In case of partial damage to the leaves, it will begin to dry at the edges. Cut or tear off the dry parts of the leaf, try not to damage the living tissue.

If the leaves have withered and become transparent (watery), most likely, they will not survive. The best solution is to cut it completely. Prune it where it joins the stem. Leave the stems to grow, they will produce chlorophyll, and the plant will accumulate strength to recover next year.

In the worst case, if the stems are also frozen, try to cut them not too close to the roots. Otherwise, you can damage the dormant buds hiding in the axils of the stems, and next year the hostas will be small and not dense. Prune the stems at the height of at least 2 inches above ground level.

As I mentioned earlier, hostas can start to rot after frostbite. So you should keep an eye on them. If you notice the first signs of crown rot, then remove the affected tissue and spray the plant and the affected area with a fungicide designed for this purpose.

Additional measures to reduce frost damage

  • Create a complete shade for the hosta. After significant damage, the plant needs the most favorable conditions. Therefore, if it grew in partial sun, provide it with maximum shade. A healthy plant can withstand partial sun; the weakened need more gentle conditions.
  • Give the plant enough moisture. The soil should be slightly moist, do not let it dry completely. The plant needs a lot of moisture to recover. However, you should not overwater it because it can lead to rot of the crown.
  • Fertilize the hosta. The plant needs a lot of energy to recover quickly, so you need to fertilize it. In addition to organic compost and slow-release fertilizers, water the hosta once or twice a season with liquid fertilizer. You can also spray it with foliar fertilizer no more than twice a year.
  • Pour a layer of mulch around. Pine bark or shredded hardwood bark is best suited as mulch. These types of mulch will cope well with moisture retention in the soil and protect the plant during the winter. The thickness of the layer should be 1-2 inches. Do not pour too much mulch, and do not pour mulch on the stems.
  • Be sure to spray the hosta from diseases and pests. You need to act ahead and not wait for something bad to happen. In fact, pests and diseases primarily attack weakened plants, so a frost-damaged hosta is an ideal target for them. Two or three times a season, spray the plant with various fungicides and pesticides from reliable manufacturers.
  • Protect hostas from snails. As in the previous case, you should use all methods of protection against snails. Iron sulfate and beer traps are best for this. I recommend using both of these methods together to get a good result.
  • In no case, do not transplant or divide the hostas. This can lead to even greater weakening, and as a result, the plants will recover for a very long time.