The pruning low-down

February to early spring is a time when Azaleas and Rhododendrons may be pruned if major containment and reshaping is desired, but this year's flowers will be sacrificed. Otherwise, they should be pruned during or just after flowering.

Some varieties of Hydrangeas are commonly pruned to the ground in February. Bigleaf (many of the shrubs with big, poofy, often blue or pink flowers) and oakleaf hydrangeas may be thinned or carefully deadheaded at this time. Major pruning will eliminate blooms for this year, as flower buds formed shortly after the flowers faded last summer. Other varieties, including panicle hydrangea, bloom on new wood, so they may be pruned heavily now.

Lilac, Japanese maples, and a number of other ornamental shrubs and trees are subject to bacterial blight, which loves wet weather. To avoid encouraging this disease, recommended pruning time for some of these plants is late summer, when weather is dry (we hope) and the plant may be in partial dormancy due to drought.

This is a good time to prune shrubs and trees that bloom in late summer to fall.
Some shrubs we can prune in February include:
Abelia
Viburnum
Laurel
Aucuba (including "Gold Dust")
Golden Rain Tree
Mimosa
Hardy Hibiscus
Barberry
Honeysuckle
Smoke Bush
Ninebark
Burning Bush
Dogwood

This is a good time to prune roses, if they weren't pruned in late summer or fall.

Some slightly more tender shrubs should wait until March for pruning. Hardy fuchsia can be pruned then, if you didn't do so in early fall; Choisya (Mexican Orange), Hebe, Caryopteris (Blue Mist Spirea), and Escallonia are other shrubs that will benefit from pruning in March.

Himalayan Honeysuckle (Leycesteria) and Butterfly Bush can be cut very low in spring; this will promote robust new growth and maximum flowering.
For many ornamental flowering trees and shrubs, particularly the spring bloomers, the safest policy is to wait until after they bloom to prune-- to avoid losing flower buds.
Shrubs that benefit from fairly radical pruning after they flower include Quince, Forsythia, and Beauty Bush.
Other candidates for pruning in later spring just after they bloom include Spirea, Camellia, Pieris, Magnolia and Daphne.

Conifers are not good candidates for heavy pruning, but in some conifers growth can be slowed by removing part of the "candle" (new growth at the very top of the tree) in late winter. Winter-killed branches should also be removed, and conifers can be selectively thinned by cutting a few branches all the way back to close to the trunk. Spruces, firs and Douglas-firs are best pruned in late winter. Arbor vitae and hemlocks can be pruned in late summer, though the most recommended strategy is very light pruning for shape and removal of growth defects.

Remember that pruning actually stimulates growth, so the best choice for any space in your yard is usually a plant whose natural inclination is to be not much larger than the space allows. Pruning can serve to correct problematic branch arrangements, remove dead or diseased material, remove spent flowers, stimulate bushiness and flowering, maintain desirable shape, contain size within reason, rejuvenate older plants by removing old branches and encouraging new growth, and maintain health by opening up the interior of densely branched plants to let in sunlight.
A few very rapidly growing and densely leafy shrubs, often grown as privacy hedges, can be size-contained to a large degree with frequent pruning. However, if you have a shrub that has already "gotten away from you", the best strategy for aesthetics and plant health is to take two or three years to bring the size down gradually.

Any deciduous (lose their leaves in winter) perennial flowers or ornamental grasses are likely looking dead and ugly and can be cut to the ground now, if this wasn't done in fall. This is beneficial for aesthetics and hygiene, needs no special expertise, and whether you do it or not, makes no difference in how the plant grows. Removing the dead material, apart from the obvious aesthetic benefit, will cut down on disease pathogens and bug habitat.