To The Daily Sun,
With spring's somewhat uncertain arrival we still look forward to getting outdoors more and improving the appearance of our yards. Buds on plants have sprouted and early flowering is is progress. Pruning of shrubs is not far away and in some cases should already have been done. Do you know what to do, how to do it and when it should be done?
Unfortunately, I have seen no evidence that it is common knowledge although it is not particularly difficult. So, let's look at the basics and get you on the road to better looking healthier and better flowering plants.
First .... do no harm. Stop shearing every thing in sight. Unless you want a formal look and have the right design and plants for it, do not shear anything. Do not shear your needle evergreen trees or shrubs.
The trees don't need it or want it and the shrubs (yews and junipers) are much healthier and better looking when pruned properly and less often. Deciduous shrubs (forsythia, weigela, lilac, viburnum) fare poorly under shearing although they fight to survive as plants do. But their health and the beauty that they could provide under proper care are degraded and the money you spent on them wasted.
This prompts the question: Why do people shear all their plants? Lots of reasons. They don't know how, and simply copy what others do. Another reason is improper plant selection and location which leads to overcrowding and thus shearing.
Flowering shrubs are plants meant for shrub borders and not for building foundations with a few exceptions. Good landscape design is necessary for an attractive planting with well spaced shrubs and trees for specific purposes and particular results. Another reason given for shearing is because it is faster and more efficient. That may be debatable depending upon the circumstances, but is it worth the loss of quality? Shearing produces an unnatural and formalized shape that is usually out of place with its surroundings. Shearing is usually done at the wrong time of year often resulting in the loss of flower bud formation for next spring's display. Over time shearing constricts a plants natural growth pattern, shutting out light from within and reducing the viability of latent buds and therefore the possibility of successful rejuvenation. Shearing may also be required more than once a year; pruning does not.
There are three basic kinds of growth: terminal, which are single-stemmed trees; basal growers, which are shrubs that produce many stems from a basal crown at the ground line; and intermediate growers which simply are the larger shrubs like lilac, viburnam, etc. Each of these three groups are pruned a little differently because of their size and growth habits.
Obviously, trees can only be pruned in the top part of the plant by judicial thinning of unwanted branches. Basal growers such as forsythia are pruned at the ground line only as that is where new growth should come from and not from the top of the plant. This will contain the natural size of the plant and aid flowering. Do not in any way "tip" the top branches or otherwise shape the top of basal growing shrubs as new growth will originate just below the pruning cut and not from the basal crown as desired.
Best flowering is produced on canes that are five years old at the ground line. As that is a little hard to determine, simply remove two or three of the oldest canes at the ground line each year limiting it to a maximum of one-fifth of the total number of canes.
When to prune is important but simple. Shrubs that bloom in the spring formed their flower buds on growth made the previous year. So, prune right after flowering to allow the remainder of the current year to produce new growth and buds for next spring. Shrubs that flower in late season (P.G. Hydrangea) bloom on the current year's growth and should be pruned in early spring before growth starts.
The red stem dogwood, basically a border plant, known for its bright red branches and commonly used in this vicinity but often poorly placed, should be thinned at the basal crown as above in early spring before growth starts to produce new and colorful stems each year. That's why you buy it so don't shear it. Left untended the stems grow old and thick and will attract borers and the plant will become unsightly and may eventually die.
Evergreen shrubs (yews, junipers) look more natural when pruned. Arborvitae should be sheared moderately, that is, not too tightly, in order to maintain enough density to prevent snow and ice damage.
Early spring and mid-summer are best times. Simply prune with hand shears about two thirds of the new growth To reduce size, or to rejuvenate, prune back into two-, three- or four-year-old wood, or further, on a healthy plant in early spring. Fertilize for new growth.
So, observe your plantings intelligently and learn their individual growth habits and structures. Stop butchering and start pruning for a better looking and healthier yard or business establishment.
This information may be confirmed on the website for the New Hampshire Agricultural Cooperative Service.