Premature bloom is not detrimental to the health of the flowering pears, but may hasten the need for pruning of the fruiting trees, roses and other plants that must be pruned while dormant. For example, my peach tree is normally pruned near the end of dormancy but immediately prior to bloom, which allows me plenty of time to procrastinate. If it begins to bloom prematurely and prior to pruning, such severe pruning as would be performed during dormancy would be very detrimental to the health of the now vascularly active peach. If a tree is not pruned while dormant, it would actually be better to delay pruning until later in summer, but by this time, the tree might have succumbed to the weight of its own fruit and subsequent limb failure.

Plants that are dormant during winter are most vascularly active immediately after dormancy, when floral buds are blooming and foliar buds are foliating. During this time, any pruning may cause bleeding from the cambium, which can actually deprive some of the newly emerging growth of resources. Such wounds may also be attractive to pathogens that are not active during winter when pruning should be performed. Wounds from winter pruning should not bleed because compartmentalization (healing) of the wounds begins as soon as vascular activity resumes.

Some of the most common plants that require winter pruning are the various stone-fruit (of the genus Prunus spp.), as well as apples, pears, figs, wisteria, cane berries, grapes, many roses and any pollarded trees. Of course, some emerge from dormancy sooner than others, so the earliest ones should be prioritized, but those that bloom later may be pruned later. Likewise, pruning is more important for some than for others. For example, healthy peach trees are very likely to be torn apart by the weight of their own fruit if not properly pruned. However, cherry trees, which are incidentally of the same genus, do not require substantial pruning if any is necessary at all, because the fruit is not heavy enough to compromise the structural integrity of the limbs.

Pruning of hybrid tea, grandiflora and floribunda roses, and their climbing counterparts, is also important but easy to neglect because some roses do not defoliate completely and may not seem to be dormant. Most have at least begun to abscise their foliage so that it can be shaken off during pruning. Even if foliage is not abscised, it should be removed because fungal pathogens overwinter in it and may begin to infest new foliage shortly after it emerges.

Flower of the Week: Witch hazel

My favorite feature of witch hazel, Hammamelis intermedia, is actually the intense orange and red foliar color during autumn, but the winter bloom is what it is most appreciated for. Witch hazel is most popular in colder climates where not much else blooms during winter. In the Santa Clara Valley, bloom may be somewhat inhibited if winter weather is not cool enough for a sufficient duration. Flowers of the most popular cultivars may be pale yellow, yellow, orange, brownish orange, red or scarlet. Some cultivars exhibit a more vertical structure and others are somewhat sprawling, but the height of most is limited to approximately 10 feet.

Witch hazel has somewhat discriminating cultural preferences, but can be accommodated as easily as rhododendrons or azaleas. Full sun exposure is preferred, but some shade is easily tolerated. Soil should be amended with organic matter prior to installation of new specimens.

Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com.