13 Perennials You Should Never Divide

An eye-catching border packed with season-long color makes any landscape sing, but some perennials need to be divided every few years to rejuvenate them. As a bonus, you'll wind up with more plants to add to your garden or share with friends. In general, clumping plants like daylilies or irises can be divided. Other perennials dislike being separated and should be left alone. Use our guide to keep your garden healthy, strong and beautiful. First up: Perennials you should not divide.

In areas with cool summers, lupines are prized perennials that attract butterflies and hummingbirds. The secret to beautiful lupines is rich, slightly acidic soil that drains well. This deep, tap-rooted perennial doesn’t respond well to division or disturbance, so let plants set seeds instead. Seedlings don’t always come true to parent plants, so you might be surprised by the flower colors you see. Hardy in USDA Gardening Zones 4 to 6. Pictured: Lupinus Popsicle Series Mixed.

Lavender is actually a woody shrub, which means it won’t respond well to division — your divisions will likely die. Instead, look around the plant for stems that might have layered. Layering occurs when branches that the touch soil develop roots. Cut the branch between the main plant and the layered seedling, dig up the seedling and treat it like a division. Pictured: Lavandula angustifolia 'Munstead'. 'Munstead' is one of the hardiest lavenders, surviving winters in Zones 5 to 9.

Peonies are perennials that grow in the garden from generation to generation without missing a blooming beat. Dividing this perennial, which is hardy in Zones 3 to 9, isn’t recommended. If you must divide, do it in the fall and be sure to get at least three growing points, also called eyes, with each division. More eyes per division are better.