It’s Time to Prune Trees and Shrubs

Posted on Sunday, June 27, 2021 · Leave a Comment 

By now your rhododendrons, lilacs and other spring bloomers have bloomed, and are ready to prune. By pruning now, you will not damage buds that will form later this summer and bloom next spring. This is also a good time to prune evergreens like pines and hemlocks if you are trying to control their size.

 

Let’s start with rhododendrons and azaleas, as many gardeners seem to put off pruning them until they are blocking the view out the windows. If you just want to keep your rhododendrons the same size this year as they were last year, pruning it easy: you just look at the color of the stems, and cut off the new growth which is bright green. Older growth is tan or brown.

 

Use good sharp hedge shears to prune boxwood

Make your cuts just into the green growth. By doing so you are leaving a growing point for new growth next spring. Most rhododendrons blossom on old wood, which is to say growth that occurred the year before.

 

But what if you want to seriously reduce the size of your azalea or rhododendron? You can make your cuts farther down the stems. Make cuts just above a fork or place where branches grow in two or more directions. You will be cutting away the growth of two, or even three years growth. There are dormant buds on those bare stems, and they will start new growth. The farther down the stem you cut, the longer it will take for growth to begin.

 

Most rhododendrons keep their leaves all year, but many azaleas drop their leaves and grow all new leaves each year. The old leaves of evergreen species will be a darker color than new leaves, making it easy to see new growth. By the time you read this – depending on your climate – some evergreen rhododendrons will have sent out new shoots after the flowers bloomed. In the middle of a cluster of light green leaves you may see a small very pointed bud. That is next year’s flower.

 

If you want to shape or reduce the size of your shrub and see new leaves and flower buds, you must make a decision: which is more important? Next year’s show of flowers, or getting your shrub under control? I say (as the Red Queen said in Alice and Wonderland), “Off with its head!” Since pruning is so easily put off for another year, just do it now – even if it means sacrificing some blossoms. There should always be more blossom buds that will appear later this summer.

 

Lilacs should ideally be pruned two to three weeks after pruning, but can be done now, too. Buds are developed over the summer at the tips of branches to bloom next spring.

 

If your lilacs are not blooming as well now as they have in the past, it may be because the soil pH has gotten acidic from acid rain, or from pine needles. You can collect a soil sample and send it off to your state Extension Service for testing, but if only want to know the pH, you can buy a simple test kit at your local garden center or hardware store.

 

Lilacs perform best with a soil that is near neutral (pH 7.0), or slightly higher and more alkaline. The soil test or pH kit will tell you how many pounds of lime to add per hundred square feet, but that is difficult to translate into action. So often I just wing it: I add lime around the base of a lilac and out three or four feet all around. I measure it out in a one-quart yogurt container. One quart for small lilacs, two for big ones. Not precise, but it helps. Do that now – lime takes time to change the pH.

 

If you have a pine, hemlock or spruce in your yard or up against you house, you would probably prefer it to stay the same size, or at least not to tower over the house. It’s easy to do: YOU MUST PRUNE OFF THE NEW GROWTH EVERY YEAR. Just look at the tips of the branches now. You will see that this year’s growth is a slightly different color than the rest of the branch. Just snip that off. Do it right away, this is the time to do it.

 

This young boxwood needs a light haircut to shape it

British gardeners – and hence, many American gardeners – love boxwoods. They love hedges and portly round balls. Some even create rabbits and other silly sculpture called topiary. If you have boxwoods, they need a light haircut every year in June or July. Never prune them after August, because pruning stimulates new growth and it will be tender, and turn brown and ugly in winter.

 

Prune your boxwoods with a good pair of hedge shears. Mine are about 24 inches long, with 9-inches long blades. Don’t use old rusty ones, buy a good pair such as those made by Fiskars or Barnell. Most Fiskars tools are good quality, and sold at a reasonable price. I don’t recommend electric hedge shears because they can ruin a shrub in the time it takes you to sneeze. I like light-weight shears for big jobs.

 

The same boxwood after pruning

When pruning boxwoods, just take a little off with each snip. You can work quickly, but just take a little at a time so you can get the exact shape you want and don’t create holes with a big cut.

 

Pruning can be fun. You can create a lovely piece of art if you take your time and step back to look at it as you go along. And if you goof, and create an “oops”, well it will all grow back. So go for it!

 

Henry is a professional pruner and gardening consultant living in Cornish Flat, NH. Reach him at PO Box 364, Cornish Flat, NH 03746. Please include a SASE if you want a response by mail. E-mail is better and faster: henry.homeyer@comcast.net.

 

Filed under Article · Tagged with boxwood pruning before and after, pruning azaleas, pruning shrubs

What Your Roses, Peegee Hydrangeas and Lilacs Need Now

My roses are waking up, and starting to show leaf buds along their stems. This is a good time to cut back dead stems, which will stimulate new growth and start them off well for the summer season. It’s time to shape your roses so that they are as good-looking now as they were when you bought them.

When I was a boy, roses were fussy. My parents bought a house in the country in June, when all the roses were in bloom. Those roses, I imagine, helped clinch the deal. But within a few years they were gone. Diseases, bugs and beetles had ravaged them. We didn’t spray with toxic chemicals, and many of those roses depended on toxic sprays, I suppose.

Now breeders have created roses that rarely get black spot, and are not very attractive to rose chafers and Japanese beetles because they don’t have a strong floral scent. Sure, Japanese beetles sometimes find my bodacious pink or red blossoms, but I just pull them off the beetles and drop them in soapy water – or crush them.

Knockout rose in summer

My favorite series of roses are the ‘Knockout’ roses. These beauties start blooming in June, and continue to produce blossoms until hard frost. It’s not unusual for my plants to be blooming at Halloween. There are others that are probably just as good, so ask at your local family-owned garden center. ‘At Last’, a Proven Winner rose, is another favorite of mine, in part because it is lightly fragrant, too.

On a recent sunny afternoon I took my pruning shears and went outdoors to give my roses a haircut. It was a harsh winter, and many stems were dead near their tips, and a few canes were dead all the way back to the ground.

I took time to really look at the stems of the roses. What I wanted to do was remove the dead material back to the highest bud that was alive and active – and outward facing. I looked for signs of life, which were buds starting to produce leaves. Dead stems are generally brown, and live stems are green or reddish.

Cut back until you see green beneath the outer bark

How should you make your cut? On an angle, just a little above a bud. Look at the piece you cut off. If it is brown all the way through, you are looking at dead wood. You should cut lower down the stem until you see a layer of green just beneath the bark.

If you had a stem or two last year that grew more vigorously than the others, you may wish to cut them back past the first green bud. What I want is a well-balanced plant, not a lopsided plant, or one with a very tall leader. Some rosarians (rose-obsessed gardeners) like to cut back most stems to within 6 inches of the ground, and let the entire bush grow up each year from the ground.

Some roses bloom on old wood, not new growth. Rugosa or beach roses are like that, as well as some once-a-season old fashioned roses. Those are best pruned for shape of the bush after blooming, but dead wood can be taken out now.

This summer you will want to snip off spent blossoms. After blooming, cut back the stem to a mature leaf cluster which has 5 or 7 leaves. Cutting back to clusters of only 3 leaves won’t stimulate the rose to re-bloom.

A word on fertilizing. I am not keen on fertilizing roses, as it tends to make them grow too fast. Often fast growth is weak, with stems that flop. But if you feel you need to fertilize, do so after the first flush of blossoms, not now. Re-blooming roses like the Knockouts tend to re-bloom every 5 to 6 weeks.

I admit to being negligent when it comes to pruning back my PeeGee hydrangea, so this year I have given it a good hard prune. It’s best to do while the plant is still dormant, or just waking up. I cut last year’s stems that blossomed back to big, fat older stems. These hydrangeas bloom on new wood, and pruning now will stimulate new growth – and lots of blossoms. The PeeGee is a shrub, but can get too tall and wide unless you prune it.

When pruning, you will find some stems that are dead near their tips. Cut those back until you see a layer of green beneath the bark. That indicates that it is alive there. As with roses, always cut back to just above a bud, or to a bigger branch.

Remove any spindly, weak branches, or any that aim back into the middle of the plant. If you have branches that have the potential to poke someone in the eye, cut them back!

Do not hesitate to prune your hydrangeas hard. Decide what size plant works best in the space you have, and prune until you have reached the right size. You won’t kill your plant by pruning. Opening up the middle of a shrub allows more sunlight to reach the leaves, which helps prevent fungal diseases.

Lilacs will be blooming soon, so you may want to wait until after they bloom to prune them. Pruning now just means that you will have fewer blossoms this spring. But if you want to help your lilacs to have better blossoms next year, spread some limestone or wood ashes in a circle around them. Lilacs like neutral or slightly alkaline soil, and limestone helps to achieve that.

Pruning, to me, is like sculpting. Done well, it creates plants that are gorgeous – even when they are not in bloom.

Henry can be reached at henry.homeyer@comcast.net. Read his blog posts at https://dailyuv.com/gardeningguy.

Copyright © 2014 Henry Homeyer

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