Pruning is one of those tasks in the garden that scares a lot of people. Proper pruning will make for a more attractive shrub, will encourage better flowering on a clematis, or will give you better fruit production. So how do you know when and what to prune.
When it comes to Spring flowering shrubs, the best time to prune is after they’ve flowered. If you prune them before flowering, or even in the Fall, you’ll reduce the number of flowers you get. I’m always a week or two behind most of you. I seem to have a climate all to myself, but then, every gardener says the same thing. Lilacs, forsythia, serviceberries, magnolias and crab apples can all be pruned now. It’s also a good time to remove older growth on forsythia, dogwoods and mock orange (once they’ve finished flowering) to encourage more flowers for next year and, in the case of dogwoods, more colourful stems, assuming you have a red or yellow stemmed dogwood. Don’t be afraid to cut these stems right to the ground. Bridalwreath spireas (the romantic ones with the cascading branches weighed down with white flowers), weigelas, beautybush, abelias, azaleas, deutzias, mock orange and rhododendrons are all flowering now. After they’ve finished, you can go about removing their faded flowers and shaping them if you’re not into the wild look. I, personally, like my plants on the Steve Martin side. That’s wild and crazy for those of you on the younger side of 40. The rest of us just held our arms out and flailed around a bit. Don’t worry, your parents aren’t having a stroke, they’re just being nostalgic.
It stands to reason that you’ll be pruning all of your Spring and Summer flowering shrubs after they’ve finished flowering. The late bloomers, you’ll prune in the early Spring. There. You’ve learned how to prune a large group of plants and without a brain hemorrhage.
One group that confuses many people, even experienced gardeners, are the hydrangea. There are primarily three different kinds of hydrangea that grow (and flower) up here. Annabelles (H. arborescens) are the big white balls that bloom during the summer and are prone to falling over. There’s more to the species than Annabelle but she’s the most common. I like to cut down Annabelle to about a foot in the early Spring. The second group is the mopheads. These have the big blue and pink flowers, although they do come in white. If you have an older variety, they only bloom on old wood. These I don’t prune until well into June, and I only remove the tips that aren’t producing leaves. Stems from last year can look completely dead (and be brittle too) but should come to life if you let them be. If you cut them down to low, you’ll have a nice green shrub with no flowers. The newer varieties like the Endless Summer series and Forever and Ever series will bloom on old and new growth and are a little more forgiving, but you’ll get more blooms if you only remove dead tips in mid-June. The third group I’ll call the PeeGees. These have later white blooms that age to pink and are often cone shaped. They should be pruned in early Spring and can be cut back fairly hard or just dead-headed.
Clematis are another plant that confuses people. Again you have three pruning techiniques and it definitely helps to know what variety (or species) you have. Most of us don’t remember which one we have or it came with the house. You can often figure out which group you have by letting them do their thing for a year without any pruning. If they bloom in the Spring only, it’s a group 1. These should be pruned immediately after flowering and not later than July. If your clematis blooms heavily in early Summer and again, but more lightly, in the early Fall, it’s a group 2. These can be pruned after the first flush of flowers has finished. Cut them down fairly hard (to about two feet) to encourage new growth for Fall flowering. Group 3 includes the ever-popular Jackmanii. These bloom in the Summer and can be cut down hard in the Spring (to about a foot). Many species, like the Sweet Autumn Clematis also fall into this group, although they flower later. If your clematis blooms in the Fall only and usually with smaller flowers, it’s probably also a Group 3. The exception is the Group 2’s. If you pruned your Group 2 too late the previous year, it might only bloom in the Fall. The best way to tell for sure is leave it alone for one full season, starting in the Summer and continuing through to the following Summer.
The most important part of pruning is having the right tools. Keep your pruners clean and sharp to ensure clean cuts. It’s always a good idea, but not always practical, to have a jar of 10% bleach, 90% water on hand to sterilize them between plants. Use bypass pruners for most of your pruning needs. Anvil pruners (a blade on one side and a flat surface on the other) should only be used on dead wood. A good set of pruners will pay for themselves in time. I’ve had my Felcos for eight years and know people that have had them for 40 years. They have replaceable blades for when they get too worn, but I haven’t had to do that yet. Don’t use your pruners on wire or other metals or you’ll just end up replacing them (or the blades).