Posted on by tonytomeo · 2 Comments

Frost Is Simply Too Chill

Some minor frost damage is acceptable.

Chill can be good. Frost can be bad. The difference is thirteen degrees Fahrenheit. Chill is at or less than forty-five degrees. Frost is at or less than thirty-two degrees. Chill helps some flora to maintain its seasonal schedule. Frost causes some flora to freeze. Both are limiting factors of home gardening. Both are weather patterns that are limited by climate.

Many species from climates with more pronounced seasons rely on chill. They know that it occurs only during winter, and that they should bloom afterwards. Duration of such chill is more important than temperature. Any temperature at or less than forty-five degrees is equally sufficient. Within that, different species require different durations, or ‘chill hours’.

This limits the selection of many species, like various fruit trees. Citrus orchards formerly grew within the San Fernando Valley. They require no chill. Stone fruit orchards formerly grew within the Santa Clara Valley. They require a bit of chill. Pomme fruit orchards grow in the Willamette Valley. Many cultivars of pomme fruit perform best with significant chill.

Frost also limits the selection of many species. Pomme fruits do not mind it. However, if it happens late, it can ruin stone fruit bloom or developing fruit. It might damage citrus trees whenever it happens. Some climates here experience frost annually. Some experience it only rarely or mildly. Several coastal climates experience merely minor chill without frost.

Many garden enthusiasts grow a few species that are vulnerable to frost. Of course, such species are safe within frostless climates. Elsewhere, they may need shelter during cold weather. Potted vegetation may benefit from seasonal relocation. Temporary tenting can shelter imobile vegetation in the ground. Some vegetation is too large to shelter, though.

Vegetation that sustains frost damage is unsightly. However, it is best to delay pruning or grooming until subsequent frost is unlikely. Damaged outer growth insulates undamaged inner growth. Besides, pruning stimulates new and more vulnerable growth. Some types of vegetation should want only superficial grooming. Others might require major pruning.

Posted on by tonytomeo · 6 Comments

Freeze Damage Necessitates Selective Pruning

Warmth stimulates recovery from freeze damage.

Pruning at the proper time has been a concern all winter. Dormant pruning was timely as soon as defoliation began. It remains timely almost until bloom. Pollarding and coppicing are generally although unnecessarily a bit later within that range. Spring pruning begins soon after bloom. Pruning of freeze damage starts after the last reasonable threat of frost.

Frost is as variable as the many climates here. Generally, it causes more damage farther inland and at higher elevations. Conversely and generally, it causes less damage closer to the coast and at lower elevations. Many southern coastal climates experience no frost. However, frigid air drains downhill. Within any plateau, the frostiest areas are the lowest.

Last frost dates should help with scheduling of pruning or grooming of freeze damage to vulnerable vegetation. The last frost date for a climate is the average date of its last frost. Frost becomes increasingly unlikely afterward. That is the best time to add warm season vegetables and annuals to the garden. It is also when to begin grooming freeze damage.

If not too unsightly, freeze damage lingers until the last frost date for two primary reasons. It shelters vulnerable tissue below, including any new growth that develops prematurely. Also, removal of such damage stimulates new growth that would be even more exposed and innately more vulnerable to frost. However, priorities change soon after the last frost.

Then, it becomes important to groom or prune away freeze damage prior to generation of fresh new growth. For milder climates, it is already timely to do so. It might be a while for less mild climates. Even for frostless climates, this might be a good time to groom growth that is only incidentally shabby. Such grooming gets more complicated with new growth.

Many zonal geraniums are already extending new growth up through shabby old growth. Removal of such old growth or freeze damage without damaging mingling new growth is no simple task. If new growth stretches for sunlight below old growth, it might flop without support from the old growth. It may be more practical to cut all growth back to regenerate. Canna also develop similar complications.

Posted on by tonytomeo · 2 Comments

Frosted Foliage Is Ugly Foliage

Frosted foliage can be removed now.

Weather is variable everywhere. Climates and seasons are imprecisely regulating. They merely define predictable ranges of the elements of weather, such as temperature, wind, humidity, precipitation and cloudiness. As unusual as weather sometimes seems to be, it generally conforms. Winter weather is mild here, but sometimes leave vegetation frosted. 

Frost was sneaky this winter, by occurring during nights between pleasantly warm days. All elements of the weather were within ranges that are normal for local climate, but their chronology was deceptive. Frost seemed unlikely after such springlike daytime weather. Some foliage was frosted only because protection from frost seemed to be unnecessary.

Frost is now unlikely for most local climates so late in the season. Only climates that are at significant elevation or significantly inland might still experience frost. Coastal and low elevation climates are generally past their last frost dates. Some climates experience no frost at all. Except for within the coolest situations, no more vegetation should be frosted.

Therefore, it is generally safe to prune and groom away unsightly frosted vegetation. It is no longer helpful to insulate undamaged vegetation below. Any new growth that pruning of this nature may stimulate or expose should be safe from frost. Within climates that lack frost, vegetation that gets shabby from chill might also appreciate pruning and grooming.

Pruning and grooming of frosted vegetation can be challenging. Many frosted plants are already actively growing in response to warmer weather. Their new growth mingles with their damaged growth that must be removed. Efficient separation of the two requires a bit of effort and persistence. Fresh and tender new growth is innately vulnerable to damage. 

For example, small new shoots of angel’s trumpet break away very easily if bulky frosted stems fall onto or through them in the process of removal. New shoots of several types of canna emerge from the soil among old shoots while it is too early to cut the old shoots to the ground. Grooming is easier where it can happen earlier, or for cannas that grow later. 

Posted on by tonytomeo · 8 Comments

Cold Winters Have Certain Advantages

Winter frost can improve spring bloom.

Even in May, damage from the frosts of last winter is still evident among some of the more sensitive plants. Lemon trees and bougainvilleas that have not yet been pruned may still display bare stems protruding above fresher new growth. Some bougainvilleas did not survive. Those that are recovering will bloom later because replacement of foliage is their priority for now.

However, peonies, although rare, are blooming better than they have since 1991, right after one of the worst frosts in recorded history. Earlier, some lilacs, forsythias and wisterias likewise bloomed unusually well. While so many plants were succumbing to cold weather, many others were enjoying it.

The reason that peonies typically do not seem as happy locally as they are in severe climates is that they really prefer more cold weather while they are dormant through winter. Without it, they may not go completely dormant, or may not stay dormant long enough to get the rest that they need; and then wake up tired in spring. Cold winter weather promotes more adequate dormancy, which stimulates healthier growth and bloom this time of year. It all makes sense considering that peonies are naturally endemic to colder climates.

A preference for cooler winter weather is also why so many varieties of apples and pears that are grown in other regions do not perform well here. The good news is that as the fruit of local apple and pear trees matures through spring and summer, it may be of better quality that it has been for many years. Trees that typically produce sparsely may produce more abundantly this year. The weather that damaged tropical and subtropical plants was an advantage to others.

Nothing can restore cherries, apricots, peaches and any other early blooming fruit that was dislodged by late rain, but any fruit that survived may be just as unusually good as apples and pears. Not only is the best place for gardening, but minor weather problems can have certain advantages.

Posted on by tonytomeo · 8 Comments

Frost Is Just Too Cool

31218thumb
Frost makes tender foliage ugly fast.

Is it too late to warn about frost? After all the rain, the recent and sudden cold weather was quite a surprise. Fortunately, these recent frosts were relatively mild. This sort of weather is probably just enough to start to satisfy plants that require chilling through winter without causing too much damage to too many sensitive plants. So far, only the most sensitive plants, like angels’ trumpet, canna and left-out houseplants show symptoms of frost damage. (Cannas should get cut to the ground at the end of winter anyway.)

Doing without all frost sensitive plants would be too limiting. Lemon, avocado, bougainvillea, fuchsia and Australian tree fern would be off limits. Such plants are worth growing, as long as we understand the potential for occasional frost damage. Those that are too big to protect may sometimes need to get pruned for removal of stems that get killed by frost. In milder climates, such damage will be very rare. In cooler spots, damage is more common, and may involve a few tougher plants, like jacaranda.

Smaller plants that are sensitive to frost, such as jade plant, angel wing begonia and the various pelargoniums, can be grown in containers so that they can be moved to sheltered spots before the weather gets too cold for them. The most sensitive sorts need to be moved under a porch roof or eave, or maybe into a garage. More resilient plants may be safe under overhanging trees or against a wall. South or west facing stucco walls radiate a slight bit of warmth at night.

Frost sensitive plants that get too big for containers should be planted in sheltered spots, like below eaves or larger trees. If a severe frost is predicted, young plants can be protected by burlap, paper, trash bags or any convenient sheeting suspended above by stakes. Foliage that touches the sheeting may get frozen, but foliage within should be fine.

Foliage and stems that get damaged by frost should not necessarily get pruned away immediately. Although unsightly, the dead foliage insulates damaged stems below from subsequent frost. Besides, premature pruning can stimulate new growth, which is more sensitive to subsequent frost.

Posted on by tonytomeo · 13 Comments

Being Cool Might Be Overrated

31218thumbThis really is the best climate for gardening. Even though summers are mild, there are not many plants that want for more warmth. Even though winters are mild, it gets just cool enough for many plants that require winter chilling. Yet, there are a few plants, particularly plants from tropical climates, that can be damaged by frost. The best way to protect such plants from frost is to not grow them.

Of course, this oversimplified technique would prevent the cultivation of familiar plants like banana, angel wing begonia and angel’s trumpet. In cooler regions, it might involve bougainvillea, philodendron and some types of citrus. Most of us would prefer to take some degree of risk to grow marginal plants. Some may get damaged by frost and then recover. Others may be killed by frost.

Potted plants can be moved to sheltered spots when threatened by frost. Some can be brought into the home or garage temporarily. For some, the simple shelter of a porch or a dense evergreen tree might be sufficient. Bougainvillea and other plants that do not like to be potted might prefer to be planted under the eaves against a warm south-facing wall. A bit of warmth radiates from walls at night.

During the coldest nights, some of the most sensitive plants that can not be moved to shelter may need shelter brought to them. Burlap, plastic, paper or any sort of sheeting that can be temporarily suspended on stakes above the foliage should be sufficient. Leaves that touch the sheeting can potentially get frozen. The sheeting should be removed during the day so that it does not get too warm in the sunlight.

Foliage that does get damaged by frost should not be pruned away immediately. It may be unsightly, but if left for later, it helps to insulate inner foliage and stems from subsequent damage from later frost. Besides, immediate pruning stimulates new growth that will be even more sensitive to frost than was the foliage and stems that had already been damaged.

Posted on by tonytomeo · 5 Comments

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.