Some shrubs need a drastic pruning to grow again
"Fielding Questions" columnist Don Kinzler also answers questions about how to make soil work in containers and the best time to move raspberry plants.
Q: I read your article on spring yard cleanup on InForum and I have a question about the shrub in the photo. I’m wondering what it is and if I can trim it. If so, how far down I should prune it? Last year it grew funny, and the branches were bare from the ground up to about 12 inches. There was new growth on the ends of branches, but everything was bare below. I suppose it’s because it wasn’t getting trimmed? The photo is from a few years ago when it was growing normally. — Patty F.
A: The shrub is a golden leaved spirea, possibly the cultivar Gold Mound spirea, or similar. Over time, the older branches of such spireas tend to become very woody and bare on the inside, with growth only at the outer perimeter.
Luckily, a severe pruning can rejuvenate these spireas nicely, bringing back the healthy growth and appearance they once enjoyed. To rejuvenate a spirea, prune all branches back to 4 to 6 inches above ground level, and they’ll bounce back rapidly with fresh, vigorous growth this spring. This works in nearly all cases, unless a spirea has become too old and woody, but there’s no other way to bring them back to good health.
Rejuvenation pruning is best done in April before new leaves begin to emerge. Spirea cultivars like this, including Little Princess and other popular types, produce pink or lavender flowers on new wood, meaning they will bloom this summer on the new growth that bursts forth.
Spireas are best rejuvenated by pruning heavily every two to three years, to keep them vigorous. As an alternative, you can selectively prune out old, brittle branches, cutting them back to ground level to make room for fresh branches.
Q: We’d like to do our gardening in containers again this year, but when we use soil, it gets as hard as cement. What can we mix with soil so my tomatoes will flourish? — Renee G.
A: The most beautiful, fertile garden or flower bed soil works poorly in pots or containers. When these outdoor soils are placed in pots, they quickly become hard and compacted, and plants suffer.
The preferred method of gardening in containers, either vegetables or flowers, is to use a packaged potting mix. There are many brands, including Miracle-Gro Potting Mix, Schulz's Potting Mix and others that are specially formulated for use in containers. Garden centers often have brands they’ll recommend.
If someone still wants to use soil from a garden or flower bed, the best mix is this: one-third soil, one-third perlite or vermiculite, and one-third peat moss. Sometimes, though, by the time you buy the peat moss and perlite or vermiculite, it's just as economical to buy the potting mix ready-made.
I used to mix my own potting soil but discontinued it long ago. Even in the greenhouse business that we operated, we quit using actual soil in our growing mixes by the late 1980’. We found that plants grow better in the packaged, soilless mixes.
Q: We want to move our raspberry plants to a different location in our yard and we're wondering what is the best time of year to move them? — Bill S.
A: Spring is the best time to move raspberry plants, and April works well. It’s quite easy to dig and relocate them with very little transplant shock, if they’re dug before new leaves are fully expanded
When moving plants from the old raspberry patch to your new planting, select healthy plants that are young and fresh, rather than older woody canes.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at email@example.com. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.