The spring floral show has been spectacular this year.
The early forsythia blooms just when it seems spring will never come, followed by the timelessly elegant Japanese magnolias, and at the height of a southern spring, dogwoods and azaleas bloom in abundance. I love the spring bloomers, and I hate to see our botanical spring come to an end, but then again, that means the green beans and zinnias are on their way, so I guess it will be OK. Before saying “until next year” to all of our pastel spring beauties, don’t forget to give them a trim.
The best time for pruning most shrubs is late winter, but for our spring bloomers, the flower buds form on old growth, or the growth from last season. If you’ve ever pruned azaleas in winter, you were disappointed come springtime after removing all those lovely future flowers. But, now, after blooming, is the best time to prune them.
Let’s start with azaleas. The most common pruning need I see for them is height reduction. If azaleas are planted in front of a house, you may not want them to tower. It makes sense to keep them to scale with their surroundings. That being said, if they are in a side yard or back of a property, greater height is going to lead to a greater abundance of flowers; you can allow them to grow to the size you want before instigating a yearly maintenance pruning, maybe with some light pruning to allow airflow in the meantime.
The best way to prune is rarely shearing, but it is what is used most commonly. Shearing involves cutting back new growth, all to the same point. This destroys the natural form of the plant, but it also leads to vigorous growth where the cuts were made and eventually can lead to a lush exterior and empty shrub interior. A better method is thinning, or taking a branch all the way back to a lateral branch that is sprouted from the main trunk. Start with the tallest shoots, and the next tallest, until the shrub is the desired size. This will shorten limbs and allow greater light penetration into the interior of the plant, which means more leaves in the interior. At the end, you will have a healthier looking shrub with a more natural form.
For forsythia we want to use that same thinning method. Because multiple forsythia shoots come from the ground, many folks choose to take it all the back to within a few inches of the ground every year, which is more of a rejuvenation prune. If you want a slightly larger shrub, take out 1/5 of the largest and tallest canes every year, all the way to the ground.
For trees, like a Japanese magnolia, dogwood, or quince, yearly maintenance is not needed, but they do benefit from structural pruning on occasion. Removing branches that face downward or inward, have narrow crotch angles (because they are structurally unsound), that are dead or damaged, and ones that are growing closely together and are crossing or touching, is a good place to start.
Check out the UGA Extension publication “Pruning Ornamental Plants in the Landscape” for more information on pruning, and some handy diagrams of the pruning techniques I’ve described.