Written by davethetreecenters • May 11 May in the Garden

Wow, spring is really here! In warmer zones it’s almost summer, but everywhere there are flowers to enjoy, and it’s a great time to be outside, before the full heat of summer arrives. Time to fire up the barbeque, but also time to keep on top of the garden, which is developing fast, and can get out of hand if you don’t keep an eye on it. Among all the fun, have some fun preparing for the rest of the year, and for the years to come in your garden.

Prune Spring-flowering Shrubs

Shrubs that looked so lovely a few weeks ago now need some attention, if they are to look so good next year too. In colder zones you might need to wait a few weeks yet for this to happen. Some, like azaleas and rhododendrons, just need the old flower clusters removed, otherwise energy will go into seed production, instead of into next year’s flowers. Snap the cluster off, rather than cut it, if you can master the trick of doing that with a quick bend. The new shoots form just below the flower, so remove those dead flowers just below the lowest one. You normally don’t need to do more, unless it is for shaping, or to encourage bushier growth.

With most deciduous shrubs there will probably be a mass of new growth, mixed with older stems that have the remains of flowers on them. The goal is to remove most or all of those older stems that have flowered, leaving the new growth to develop for next year. Don’t be afraid to leave your bush looking a bit open and thin by the end of the job – that means you did it properly. Look first, before starting to cut. You will probably see vigorous new shoots growing from lower down. Don’t touch those, and don’t cut them at all. Instead cut the older stem back to just above the first strong one and remove it completely.

If the shrub also has berries, then of course you don’t want to remove those old stems, just prune for shape as needed.

If you are looking at old, neglected shrubs, you may need to be more drastic. Remove up to half of the oldest stems completely, low down, even if there are no new shoots showing yet to replace them. They will come. Then next year remove the other half. More cautious gardeners do it in thirds, over three years.

Brighten Up with Flowers

Shrubs, trees and groundcover are always going to be the backbone of the best gardens, and the ones that don’t take too much work. But there is always room for flowers, and May is the best month, in most places, for putting out the classic annual flowers. Make sure you choose plants for the location – sun lovers in sun, shade lovers in shade. It sounds obvious, but it can be a hard lesson for beginners. You will only be disappointed if you plant petunias underneath the spruce tree. If you have a lot of bigger bushes, consider putting those flowers in pots and planters rather than trying to get them to grow among tree roots. You can move them as needed for the best light conditions, and in their own soil, with regular fertilizer, you will be amazed at how well they will do. If you are putting down planters for the long term, place them on bricks to raise them off the soil. Amazingly, tree roots will soon find the drainage holes and grow into them if they can, stealing the water and fertilizer meant for your flowers. A gap will solve the problem.

Support your Peony Bushes

Peonies are great plants in between flowers and shrubs. The die down in fall, but their big leaves look shrub-like all summer, after they have bloomed. Some varieties are vigorous enough to stand up alone, especially if they are growing in full sun. Most of them, though, benefit from some support. Forget those peony rings – most are too low and small to do any good. Pick up some tall tomato cages and cut through the rings down one side. Stretch them out a bit and put a pair around each peony bush – this works way better than rings. Remove them once flowering is over and you have cut back the flower stalks to just above the first leaf. If you have other perennial plants like phlox, you can use these cages to support them as well.

Thin Out your Fruit Crop

If you are growing tree fruits, like apples, pears or peaches, keep an eye on the developing fruit. Once they are the size of a quarter, remove all but one from each cluster. If you don’t do this – and it does sound brutal – you will have a big crop of small fruit that is mostly core. As well, if you don’t thin, some varieties will only fruit every second year – a common tendency in neglected trees. Leave just one or two developing fruit every 6 inches along the stems.


If you are growing modern varieties, of roses, like Knockout, or Oso Easy Landscape varieties, all that spraying for diseases is a thing of the past.  If you haven’t made the switch, you should, it is liberating. But you can still get some annoying pests, like aphids – which come in green or black. These can cluster on the buds in huge numbers, sucking sap and distorting the growth. Luckily, these are easy to deal with by spraying with a strong jet of water that you have added a few drops of liquid soap to. You might need to repeat this, and don’t forget to check under the leaves as well, but it’s a pretty easy job, and needs no dangerous chemical sprays.

Watch for Weeds

One year’s seed, seven year’s weed’ is an old gardener’s saying, but it is still as true as ever. This is the month to get on top of weeds, before they grow large, and before they start seeding. Combine mulch and groundcover with weeding and learn to use a hoe. The best is called a ‘Dutch’ or ‘scuffle’ hoe in most places. It has a broad blade that lies flat on the ground. You move it back and forth just below the surface, cutting through weed roots and killing them, without disturbing the roots of your garden plants and shrubs. You can cover a big area very quickly, especially if you do it when the weeds are still small. If it is sunny, they will have withered and disappeared in a couple of hours. Don’t let those weeds get big and difficult before tackling them. If you do have larger weeds, the extra work of removing the roots will pay off, or just keep hoeing every week or two, until they give up and die – which they will if you keep it up.

Mulch is perfect for shrub beds. Use compost and other organic materials that feed your soil and plants, rather than bark and gravels. Those inert materials can even rob the soil of nutrients once they get mixed into it, which they inevitably do. Landscape fabric can often be a problem too, if weeds and grasses become established. They root through it, making it impossible to remove them. Once your beds are more established, fill in the gaps and along the front with groundcover plants. These add a whole extra dimension to your garden visually, and the best ones chock out weeds very effectively.