Pruning Rhododendrons — Seattle’s Favorite Garden Store Since 1924 – Swansons Nursery

On a dense-foliage rhody (or any dense plant), if you shorten all the tallest leaders you will likely open up bare spots — open areas with bare branches and little foliage that were previously shaded out by what you have just removed. In time, these will resprout and fill in but it can take a year or several, depending on the type and vigor of the plant.

With any major reducing, restoring or rejuvenating, we recommend to avoid (if possible) doing this all at once. If you can spread the job over two or three years you might minimize the bare or chopped look and the overreactive regrowth.

For example, you could do releadering on maybe 1/3 or 1/2 the number of tallest leaders, so the top layer is thinned out but not totally removed. Then after a year or two with the lower layers growing in, you can cut back the rest of the top layer. But remember: it may still react to a major reduction over time. Unnatural pruning creates a high-maintenance plant.

Older rhodies can develop quite a leggy habit, especially after years of being crowded by neighboring plants, struggling under dense trees, or just having aged a long time without any pruning attention. Others may suffer low vigor from poor drainage, depleted soil, or other stresses.

Restorative pruning can make quite a difference, along with improving the watering, mulching, and fertilizing of a struggling plant. If the shrub is heavily shaded (unless it’s possible to thin out overhead trees), blooming might always be sparse. And although these methods can help revive most shrubs, some might have deeper health issues and not sprout as well.

A leggy habit is long, tangled, bare branches with few leaves or flowers out on the tips. Restoring a more balanced branching pattern and redirecting growth energy back into foliage and blooming often takes a combination of thinning, untangling/reweaving, and heading back some bare branches.