Pruning to Generate Big Blooms

Most of us are “when I feel like it” plant pruners (which is usually allowed), but pruning in springtime is essential for some plants. So, get out the pruners, and take care of business on these pretty plants to keep the blooms coming.

No More Naked Rhodies

Every self-respecting South Sound gardener has at least one. It’s practically a requirement — the hybrid rhododendron. They’re easy to find, easy to grow, and rhodies love what we have to offer — rain, acidic soil, and (normally) mild winters. 

In return, the rhody gives back loads of luscious clusters of bell-shaped flowers in everything from sherbet shades to dark and dramatic reds. The flower clusters (or “trusses” in rhody-speak) are the No. 1 reason we grow them, so knowing when to prune them and keep the flowers coming is imperative. Rhodies don’t have to be pruned every year, but if you want to reduce the size or reshape one, grab your Felco 2 pruners and start trimming right after it blooms. Rhodies start making next year’s flowers immediately after blooming. Prune them any later, and you’ve lost next year’s flowers. And nobody wants to see a naked rhody.  

Azaleas need the same kind of attention. If you want to cut them back or reshape them, do the shearing when this year’s flowers start to shrivel and turn brown, i.e. when they start looking a little on the ugly side.

The Magic Date is June 15

The general rule for pruning other spring-flowering shrubs is to prune by June 15. Any later, and you lose the following year’s flower.

Forsythias, lilacs, weigela (not grown nearly enough), and viburnums all will give you more flowers next year if you prune right after they bloom. 

Evergreen clematis requires pruning from time to time to keep it under control, but a hard pruning after it has bloomed is best done in late spring. 

Spiraea varieties that are pruned and shaped after its springtime bloom will likely bloom again. Spiraea can be twiggy and unwieldy to prune, so make it easy — tightly tie up the shrub with a rope about one-fourth of the way up. Shear the part above the rope into a ball, or just to recover some symmetry. Untie, it and you have a perfectly shaped spiraea. 

Berberis (barberry) varieties are grown for their bright, fresh foliage, not their inconspicuous flowers. Those red, orange, chartreuse, and Kelly green leaves happen only on new growth, so don’t be shy about cutting them back now. 

Pruning is often the bane of gardeners. Clematis is a mystery, and that’s why we need the help of a book!

‘Pruning Simplified’

A lot of how-to pruning books are filled with good directions. That’s great if the directions are clear and if that is how you learn. Glossy pictures show before and afters, which is helpful, but there is nothing better for learning how to prune than a good line drawing with hash marks where you’re supposed to make the cuts. That’s why we like Pruning Simplified by Steven Bradley/Timber Press.

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