The Best Mulch for Peonies

About Peonies

• Two types of peonies are common in American gardens. Herbaceous peonies (P. lactiflora and hybrids) die back to ground level each winter. In the spring, they send up dark green, glossy foliage that changes to wine red in the fall. The fragrant, late-spring flowers are cup shaped and come in many colors and forms. Herbaceous peonies are hardy in U.S. Department of Agriculture plant zones 4 through 8. Tree peonies (P. suffruticosa and hybrids) are woody plants. These deciduous shrubs have large flowers with silky petals. Tree peonies are hardy in zones 5 through 8 or 9, depending on the cultivar. Both types of peonies have roots near the soil surface, which makes cultivation around the plants difficult. Use mulch to control weeds instead.

Benefits of Organic Mulch

• Always use an organic mulch around peonies to conserve moisture and discourage weeds. Straw, peat moss, composted wood chips and shredded bark are all good choices. Organic mulches decompose over time and need to be topped off every year or two, but that's a good thing. The decomposing mulch adds nutrients back into the soil, replenishing micro-nutrients that aren't available in commercial fertilizers. Stone mulch does nothing to replenish the soil and makes the root zone warmer. Landscape cloth does discourage weeds but needs a layer of organic mulch over it to be attractive. It can also be difficult to remove without damaging the peonies if you need to divide or relocate them.

A Caution

• Herbaceous peonies won't flower if they're planted too deeply. The plant's crown, which contains the latent eyes, or buds, can't be more than 1 to 2 inches below the soil surface or the plant will produce foliage but not flowers. From a peony's point of view, mulch over the crown is as bad as soil, so always keep the mulch several inches away from the crown. Depth isn't an issue with tree peonies, but it's a good idea to keep the mulch an inch or so away from the woody stems to avoid trapping moisture near the bark.

The Best Mulches

• Shredded bark, pine needles and other organic materials make the best mulch for your peony plants, since they prevent weed growth, conserve moisture and add nutrients back into the soil as they decompose. Keep mulch several inches away from the crown of deciduous peonies and at least 1 to 2 inches away from the stems of tree peonies.