Dormancy And Defoliation Are Advantageous

Hostas go dormant and defoliate for winter, and regenerate for spring.

Many plants are deciduous in autumn and winter, which means that they defoliate or die back, and then refoliate or regenerate in spring. Many others are evergreen, which simply means that they are always foliated through all seasons. What many people do not realize is that evergreen plants replace their foliage just like deciduous plants do. They just do not do it in such distinct phases of defoliation, dormancy and refoliation.

Tropical plants like cannas and some of the various begonias really have no need for formal defoliation, since they are from climates that lack winter. In the wild, they continually and systematically shed old stems as they produce new stems. Locally, they tend to shed more than they grow during late autumn and winter. The large types of begonias tend to keep their canes for so many years that it is not so obvious. Where winters are colder, cannas freeze to the ground, only to regenerate from their thick rhizomes as winter ends.

Zonal geraniums may seem rather tired this time of year for the opposite reason. They expect late autumn weather to include frost that would kill them back to the ground where they would stay relatively dormant until warmer weather after winter. Just because their foliage is instead evergreen through winter does not mean that it should be. It lingers and often becomes infested with mildew and rust (fungal diseases) that proliferate in humid autumn weather.

However, zonal geraniums need not be pruned back just yet. Even if they eventually get damaged by frost, pruning should be delayed so that the already damaged older foliage and stems can shelter the even more sensitive new growth as it emerges below. They can get cut back after frost would be likely.

Evergreen pear can get very spotty once the warm weather runs out because the same damp and cool weather that inhibits its growth also promotes proliferation of the blight that damages and discolors the foliage. The damaged foliage eventually gets replaced as new foliage emerges in spring, but will remain spotty and discolored until then. Photinia does not get as spotty, but holds blighted foliage longer into the following summer. Ivy can be temporarily damaged by a visually similar blight.

Prune Fruit Trees While Dormant

Dormant fruit trees should be pruned aggressively.

After centuries of breeding for abundant production of unnaturally large fruit, deciduous fruit trees have become dependent on specialized pruning while they are dormant through winter. Without pruning, most eventually become overgrown and overwhelmed by their own fruit. The weight of excessive fruit disfigures and breaks limbs. Pathogens proliferate within distressed foliage, crowded fruit and surplus fruit that falls to the ground.

Pruning not only improves the structural integrity of the limbs, but also limits the production and weight of the fruit that will be produced. Limiting production concentrates resources, so that there are fewer, but considerably better fruits, instead of too many inferior fruits. Concentrating the growth of the fewer new stems that develop in spring promotes vigorous growth that is more resistant to pathogens. Ideally, pruning also limits the height of fruit trees, so that much of the fruit develops closer to the ground.

Peaches, nectarines, apricots, plums, prunes, and cherries are all relates ‘stone’ fruits (of the genus Prunus), so require various degrees of similar pruning. Peach trees produce the heaviest fruit, so need the most aggressive pruning. Cherries trees produce significantly lighter and smaller fruit, so get pruned relatively minimally. Almonds (which are actually the ‘pits’ of a similar type of stone fruit) get shaken from their trees, so there is no advantage to keeping production close to the ground.

The ‘four Ds,’ which are ‘Dead, Dying, Diseased and Damaged’ stems should be pruned out first. Then the vigorous stems that grew last year should be thinned and cut back, but not removed completely. They are the stems that will bloom and develop fruit the following year. Pomme fruits, such as apples, pears and quinces, develop on similar newer stems that should likewise be pruned down, but many also develop on lower ‘spur’ stems that elongate so slowly that many spurs may never need to be pruned.

Most young deciduous fruit trees will need more pruning each year as they grow. Fortunately, pruning becomes more familiar with experience. Because pruning fruit trees is so specialized and important, it is worth studying more thoroughly.

Dormancy And Defoliation Are Advantageous

Kahili ginger is finished blooming, and should get cut back once the foliage succumbs to frost.

Many plants are deciduous in autumn and winter, which means that they defoliate or die back, and then refoliate or regenerate in spring. Many others are evergreen, which simply means that they are always foliated through all seasons. What many people do not realize is that evergreen plants replace their foliage just like deciduous plants do. They just do not do it in such distinct phases of defoliation, dormancy and refoliation.

Tropical plants like cannas and some of the various begonias really have no need for formal defoliation, since they are from climates that lack winter. In the wild, they continually and systematically shed old stems as they produce new stems. Locally, they tend to shed more than they grow during late autumn and winter. The large types of begonias tend to keep their canes for so many years that it is not so obvious. Where winters are colder, cannas freeze to the ground, only to regenerate from their thick rhizomes as winter ends.

Zonal geraniums may seem rather tired this time of year for the opposite reason. They expect late autumn weather to include frost that would kill them back to the ground where they would stay relatively dormant until warmer weather after winter. Just because their foliage is instead evergreen through winter does not mean that it should be. It lingers and often becomes infested with mildew and rust (fungal diseases) that proliferate in humid autumn weather.

However, zonal geraniums need not be pruned back just yet. Even if they eventually get damaged by frost, pruning should be delayed so that the already damaged older foliage and stems can shelter the even more sensitive new growth as it emerges below. They can get cut back after frost would be likely.

Evergreen pear can get very spotty once the warm weather runs out because the same damp and cool weather that inhibits its growth also promotes proliferation of the blight that damages and discolors the foliage. The damaged foliage eventually gets replaced as new foliage emerges in spring, but will remain spotty and discolored until then. Photinia does not get as spotty, but holds blighted foliage longer into the following summer. Ivy can be temporarily damaged by a visually similar blight.