Jack Frost Nipping At Foliage

Yuck! Freezer burn!

It is impossible to deny that the weather has been unusually cold when tough perennials like ligularia and farfugium express symptoms of frost damage. Late autumn and winter are expected to be cold, but not as cold as it has been recently. Ligularia, farfugium and most tough perennials should recover as if nothing happened. Cannas will naturally die back or need to be cut back to the ground later, but their resilient rhizomes should be safe, and regenerate later as winter ends. Unfortunately, sensitive perennials like pelargoniums may have been killed if frost damage extended too far into lower stems and roots.

The best way to protect plants from frost is to grow only plants that are not so vulnerable to frost. The problem with this technique is that it is too limiting. Abstaining from the few most sensitive plants like bananas and angel wing begonia probably would not be a problem for most of us. However, avoidance of moderately sensitive plants would involve familiar plants like bougainvilleas, lemons and split leaf philodendron.

Many of the smaller sensitive plants like angel wing begonia, can be grown in containers that can be moved to more sheltered spots if and when necessary. They can be brought inside or moved onto covered porches. If they only need to be protected for a few days during the coldest weather, they can be moved into garages. The problem with this technique is that many plants get too big for containers.

Bougainvilleas eventually get big, and do not like to be grown in containers anyway. They should be planted in warm spots in the garden not only because their foliage can be damaged by frost in winter, but also because they like warmth during summer. A south facing wall with an eave above provides a nice warm exposure, a bit of protection from frost above, and a slight bit of ambient warmth from the building behind it. Even if the foliage gets frosted, the main stems within should be safe.

During the coldest nights, sensitive foliage can be protected by burlap, paper, plastic or any sheeting suspended above by stakes or any light framework. With this technique, only exposed foliage or foliage that touches the sheeting will be damaged. It is unfortunately not practical to tent large plants like giant bird-of-paradise.

Even though it is unsightly, unprotected foliage and stems that get damaged by frost should not necessarily be pruned away immediately. This damaged foliage insulates and protects sensitive stems below. Besides, such early pruning can stimulate new growth that will be even more sensitive to frost later.

Frost!

Fire and Ice! Frost becomes a concern at about the same time that fire season ends here. Like the article about fire yesterday, this article is from three years ago, in fact, at about the same time.

Tony Tomeo

P71208+K1Yes, we get it too. It took a while, but we finally got it just like most of everyone else in North America and the Northern part of the Norther Hemisphere. It is not much to brag about, but it is enough to melt the big feral pumpkin vine that I wrote about earlier ( https://tonytomeo.wordpress.com/2017/12/03/too-late-for-pie/ ). It has actually been frosting for a few nights. I just got around to getting this picture this morning.

Now that the foliage is melting and collapsing, a leak is now visible in the exposed valve manifold that was obscured in the previous picture. It did not get cold enough to freeze the pipe, so the water was dripping freely. This confirms the earlier theory about where the pumpkin vine was getting water from.

Two pumpkins are also exposed by the collapsing foliage. They were not visible earlier. Unfortunately, they are too under-developed…

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Frost Is Now Old News

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Minor frost can cause major damage.

Frost was something of a nonissue for some of us this winter. For those of us in milder climates, in rarely is. Those who limit selection of what grows in their gardens to species that are resilient to frost need not be concerned with it. Those of us who enjoy gardening a bit too much are more likely to grow a few marginal species that would prefer to be somewhere with milder winter weather.

Protection from frost might have been a concern prior to the onset of cold weather. Then, there was more concern for the few plants that might have been damaged by frost. Grooming and pruning of damaged foliage and stems needed to be delayed until after the threat of subsequent frost. Now that it is so late in the season, subsequent frost is very unlikely. It is safe to clean up any mess.

Pruning and grooming of foliage and stems that were damaged by frost is delayed for two main reasons. Firstly, the damaged material, although unsightly, helps insulate undamaged foliage and stems below it from subsequent frost. Secondly, premature removal of damaged material stimulates premature development of new foliage and stems that are more sensitive to subsequent frost.

Not only is it now safe to prune and groom frost damaged plants, but such procedures should not be delayed while affected plants recover. The same frost damaged material that provided a bit of protective insulation earlier would now interfere with the healthy development of new stems and foliage. Pruning can now promote new growth that was preferably delayed through colder weather.

Because the weather has been so pleasantly mild for quite a while already, new growth may already be developing among some frost damaged plants. Damaged material should be removed as carefully as possible to limit damage to such new growth. Many perennials that were not damaged this year might be pruned as if they were, to remove tired old growth, and promote new growth.

Many of the dormant spores of fungal and bacterial pathogens that overwinter in old foliage will be removed as such foliage gets groomed away.

Frost Is History For Now

80328thumbThere is no doubt that frost will return next autumn. It does that every year. Right now, we are more concerned that is should not return prior to that. It is now safe to plant plants that are sensitive to frost. Even if the weather were to somehow get cold enough to necessitate protection of frost sensitive plants, it will not be severely cold, and it will not last long. It is best to start now than to delay.

It is also safe to prune away foliage and stems that were damaged by frost through winter. It was best to leave it in place through winter, both to provide a bit of insulation for undamaged stems below, and to not promote new growth. Pruning it away allows warming sunlight to the undamaged stems, and stimulates generation of new growth. A bit of new growth might already be apparent.

Many leafy perennials can be cut to the ground, or at least just above their rhizomes. The tall vertical canes of cannas can be cut back to the low horizontal rhizomes that creep along the ground. The canes are not really stems anyway, but are merely upright foliar shoots. Any shorter new shoots that are beginning to develop can remain, even if a few outer leaves happen to be damaged.

Zonal geraniums can likewise be pruned almost to the ground, leaving only stubs of lower stems, even if only upper and outer foliage was damaged by frost. Although they do not need to be cut back so severely, they respond to such pruning splendidly, with vigorous new stems and foliage. The fungal foliar disease known as ‘rust’ overwinters in old leaves that get removed in the process.

Lemons, limes and any other citrus that were damaged by frost only need to have their damaged stems removed as far back as viable growth, where new buds might already be visible. However, if more pruning is necessary, this would be a good time to do it. Major pruning should not be done later in summer because the sensitive bark of inner stems can be scalded by sudden exposure to too much sunlight. Small trees that are sensitive to frost become more resilient as the grow larger.

Jack Frost Was Sneaky Again

71227thumbTiming is very important in gardening. Even when the weather in autumn still seems like summer, spring blooming bulbs must be planted on time. Bare root fruit trees will become available while they are dormant, and will need to be planted before they wake up. Roses need to be pruned before buds for new canes swell later in winter, even if their old canes are still awake and blooming.

Some procedures are influenced more by environmental factors than timing. Planting bare root fruit trees and pruning roses must be done sooner if the weather gets warm sooner than expected. Irrigation must be increased in summer, but only as warm and dry weather necessitates such increase. It gets decreased in winter, but only as weather gets cooler and rainier. Then there is frost.

Frost arrives differently every year, and is of course worse some years than others. It is only a minimal threat in some regions, but limits what can be grown in others. It happened to be sneaky this year, by hiding in between remarkably pleasant days. While the daytime weather is so mild and even unseasonally warm, a weather forecast may provide the only early warning of overnight frost.

By now, sensitive plants were either protected successfully, or possibly damaged by earlier frosts. Potted plants got moved to shelter under porch roofs, or maybe dense evergreen trees near the home. Those in the ground might have been tented with plastic or sheeting suspended above the foliage by sticks and maybe string. Old fashioned Christmas lights might have softened the chill.

Many perennials and annuals are just left out to succumb to the cold. Any remaining warm season vegetable plants are not worth protecting. They will not produce anything this late anyway. Canna and ginger can likewise be left out in the cold for their foliage to freeze and collapse to the ground. If protected, they can stay green through winter, but will replace their foliage in spring anyway.

Foliage of hosta and dahlia can be removed because the dormant parts of the plants are safe below the surface of the soil. Canna and ginger rhizomes on the surface of the soil might appreciate a bit of mulch if their foliage gets removed. Frost damaged stems of woody plants should not be pruned out too early. Premature pruning stimulates new growth that will be sensitive to later frosts.

Frost!

P71208+K1Yes, we get it too. It took a while, but we finally got it just like most of everyone else in North America and the Northern part of the Norther Hemisphere. It is not much to brag about, but it is enough to melt the big feral pumpkin vine that I wrote about earlier ( https://tonytomeo.wordpress.com/2017/12/03/too-late-for-pie/ ). It has actually been frosting for a few nights. I just got around to getting this picture this morning.

Now that the foliage is melting and collapsing, a leak is now visible in the exposed valve manifold that was obscured in the previous picture. It did not get cold enough to freeze the pipe, so the water was dripping freely. This confirms the earlier theory about where the pumpkin vine was getting water from.

Two pumpkins are also exposed by the collapsing foliage. They were not visible earlier. Unfortunately, they are too under-developed to mature and ripen. A neighbor will likely take them and set them aside on the porch, just in case they are able to finish ripening. It would be nice if they did. The vine certainly put a lot of work into them!P71208+K2P71208+K3

While taking this picture, I was reminded why people who live with cooler weather dislike it so. First of all, and most obviously, it kills things. The season is over for pumpkin vines, which is not a problem. The problem is that so many of the citrus, avocados and other plants from mild climates that we grow so easily here get damaged or killed by frost in other climates.

The second reason to dislike cool weather is that it is too cool, maybe even cold. It is uncomfortable to be out in long enough to walk over and get these pictures of the pumpkin vine and pumpkins. I am glad that it does not get much colder here.