Gardening Tip: Pruning Rabbitbrushes

Rabbitbrush shrubs need spring pruning.

Spring is almost here. The weather in Mother Nature’s Montrose Garden fluctuates between the chilly 40’s and pleasantly warm, although most nights hover around freezing. Some of the hardier shrubs are just beginning to leaf out.  One group of native bush Sunflowers – the Rabbitbrushes – are among the first.  And that means it’s time to prune them!

Several species of Rabbitbrush are native to the Four Corners states. We’ll feature a few as Plants of the Month in the coming year.  But in terms of pruning, the rules are pretty much the same.  Rabbitbrushes are pruned in early spring, when they begin to bud out – much like their cousins the Artemisias. And they are pruned quite substantially; also like some of the Artemisias.

Budbreak in Rabbitbush

In the wilds, bush Sunflowers like the Rabbitbrushes provide important winter browse for large animals like deer and elk, as well as smaller mammals (rabbits, ground squirrels, pocket gophers, etc.).  By late winter, plants are often severely eaten down by the wildlife. And, since The Rabbitbrushes and their native ‘pruners’ evolved together, Rabbitbrushes have developed the ability to grow back vigorously each spring.

Begin pruning Rabbitbrush the year after planting.

In fact, many native bush Sunflowers need a good pruning each spring. If they don’t get it, plants become woody, leggy – in short, less attractive than they should be. And pruning needs to begin in the first year after planting to keep a Rabbitbrush shrub full and lush (as they are in the wilds).

Rabbitbrush in early spring. Note green stems and sprouting buds.

Unlike some shrubs, Rabbitbrushes retain the ability to sprout from older wood. As shown above, even branches with a diameter of an inch or so are green; and buds can be seen below the cut.    This means you can prune a Rabbitbrush branch quite hard, as long as you leave at least four buds below the cut. 

Rabbitbrush before spring pruning.

Above is a Rabbitbrush before pruning.  The shrub was left unpruned over the winter (you can still see remnants of flowers and old leaves).  In colder climates (we’re USDA Zone 6), old growth is left on the plants to protect them from winter chill.

Partially pruned Rabbitbrush.

To give you an idea of our recommended pruning strategy, the picture above shows a plant that is half pruned.  You can see that quite a bit of mass – up to two-thirds of the branch length – can be removed, as long as there are heathy buds beneath.  The photo below shows a fully pruned bush.

Fully pruning Rabbitbrush.

At this point we leave the prunings around the plant to protect it and conserve soil moisture.  When the trimmings are dry, we’ll cut them into smaller pieces and use them as mulch.  And that’s pretty much all there is to say about pruning Rabbitbrushes.

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We welcome your comments (below).  You can also send your questions to: monaturesmontrosegarden@gmail.com