Peony Care Guide: Growing Magnificent Blooms
Peonies are treasured for their lush foliage and spectacular, often fragrant flowers in shades of pink, red, white, coral, and yellow. These long-lived perennials can grace gardens for generations, becoming cherished focal points in late spring and early summer. While known for being relatively low-maintenance once established, success with peonies hinges on proper planting – especially planting depth – and providing good air circulation to prevent disease.
Types of Peonies
Understanding the main types helps with selection and care:
Herbaceous Peonies (Paeonia lactiflora & hybrids)
- Most common type. Dies back to the ground each winter.
- Grow from thick, fleshy roots with 'eyes' (buds).
- Need winter chill to set buds properly.
- Flowers can be single, semi-double, double, Japanese, or anemone form.
- Often require staking due to heavy blooms.
- Examples: 'Sarah Bernhardt', 'Karl Rosenfield', 'Festiva Maxima'.
Tree Peonies (Paeonia suffruticosa & hybrids)
- Woody shrubs that do not die back to the ground.
- Produce very large flowers, often earlier than herbaceous types.
- Slower growing and generally more expensive.
- Prefer dappled shade or morning sun, especially in hot climates.
- Grafted onto herbaceous rootstock; plant graft union below soil level.
- Less commonly grown but spectacular.
Itoh Peonies (Intersectional Hybrids)
- Cross between herbaceous and tree peonies.
- Combine the best traits: large flowers (like tree), sturdy stems (less staking needed), herbaceous die-back habit, and extended bloom season.
- Often feature yellow and apricot colors not common in herbaceous types.
- Vigorous growers, disease resistant.
- Examples: 'Bartzella', 'Cora Louise', 'Sequestered Sunshine'.
Planting Peonies
Planting depth is the single most critical factor for herbaceous peonies. Fall is the preferred planting time.
When to Plant
- Fall (September/October): Ideal time for planting bare-root herbaceous and Itoh peonies. Allows roots to establish before winter.
- Spring: Possible to plant container-grown peonies or bare roots, but fall is better. Spring-planted bare roots may establish more slowly.
Ideal Growing Conditions
- Light: Full sun (6-8 hours) is best for herbaceous and Itoh peonies to ensure abundant flowering. Tree peonies appreciate some afternoon shade in hot climates.
- Soil: Fertile, humus-rich, well-draining soil. Peonies detest wet feet. Neutral to slightly alkaline pH is preferred.
- Spacing: Give them room! Space herbaceous and Itoh peonies 3-4 feet apart. Tree peonies can eventually reach 5 feet wide or more. Good air circulation is vital to prevent fungal diseases.
Planting Technique (Herbaceous & Itoh - Bare Root)
Choose a sunny, well-drained location away from competing tree/shrub roots. Amend the soil generously with compost.
Dig a hole about 18 inches deep and wide. Mix compost and a handful of bone meal or low-nitrogen fertilizer into the bottom soil (optional).
CRUCIAL STEP: Place the bare root division in the hole so the 'eyes' (pinkish buds on the crown) are facing upwards and are NO DEEPER than 1.5 to 2 inches below the final soil surface. Planting too deep is the #1 reason peonies fail to bloom. In warmer zones (7-8), plant even shallower, with eyes just 1 inch deep.
Fill the hole with the amended soil, working it around the roots. Gently firm the soil. Ensure the eyes remain at the correct shallow depth.
Water thoroughly. Apply a light layer (1-2 inches) of mulch after the ground freezes in cold climates, keeping it away from the crown. Remove excess mulch in spring.
Planting herbaceous peony eyes deeper than 2 inches will result in a healthy green plant that produces few or no flowers. If your established peony isn't blooming, check the planting depth first!
Tree Peonies: Plant the graft union (the bulge where the tree peony scion joins the herbaceous rootstock) about 4-6 inches below the soil surface. This encourages the tree peony part to form its own roots.
Watering Peonies
- Water regularly during the first growing season to help establishment.
- Mature peonies are relatively drought-tolerant but perform best with consistent moisture, especially in spring when buds are forming and during flowering.
- Water deeply when the top few inches of soil are dry. Avoid frequent shallow watering.
Fertilizing Peonies
- Peonies are not heavy feeders. Over-fertilizing, especially with nitrogen, can lead to weak stems and fewer flowers.
- Apply a light application of low-nitrogen fertilizer (e.g., 5-10-10) or bone meal around the drip line of the plant in early spring as growth emerges, or alternatively in the fall. Compost is also beneficial.
- Avoid fertilizing right at the crown.
Supporting Peonies
- The large, heavy flowers of many double herbaceous peonies often cause stems to flop, especially after rain.
- Install supports EARLY in spring, before plants get too large. Options include:
- Grow-through grid supports (place over plant early)
- Ring-style supports (peony hoops)
- Individual stakes and twine (more work)
- Itoh peonies generally have stronger stems and rarely need staking. Tree peonies have woody stems and don't need support.
Maintenance
Deadheading
- Remove spent flowers by cutting the stem back to a strong leaf node. This prevents seed formation and keeps the plant looking tidy. Do not remove foliage when deadheading.
Fall Cleanup (Herbaceous & Itoh)
- After the first hard frost has killed the foliage, cut herbaceous and Itoh peony stems down to about 1-2 inches above the ground.
- Crucial: Remove and destroy (do not compost) the cut foliage. This helps prevent overwintering fungal diseases like botrytis blight.
Tree Peony Pruning
- Tree peonies require minimal pruning. Only remove dead or damaged wood in early spring. Avoid heavy pruning.
Troubleshooting Common Problems
Failure to Bloom
Possible Causes and Solutions
- Planted too deep (Herbaceous/Itoh): #1 cause! Eyes must be 1-2 inches below surface. Carefully lift and replant shallower in the fall.
- Too much shade: Need at least 6 hours of full sun.
- Immature plant: Newly planted peonies (especially bare root) may take 2-3 years to bloom well. Be patient!
- Over/Under Fertilizing: Too much nitrogen = weak stems, few flowers. Not enough phosphorus can also impact blooms. Use low-N fertilizer lightly.
- Competition: Roots from nearby trees/shrubs stealing nutrients/water.
- Botrytis Blight: Fungal disease can blast buds before they open (see below).
- Late Frost: Can damage emerging buds.
- Divided too recently: May take a year or two to recover.
Fungal Diseases (Botrytis Blight, Powdery Mildew, Leaf Blotch)
Symptoms and Management
- Botrytis Blight: Most common. Gray mold causing buds to rot, stems to wilt near base, spots on leaves. Thrives in cool, wet spring weather.
- Powdery Mildew: White coating on leaves, usually later in season, mostly cosmetic.
- Leaf Blotch/Spot: Purple or brown spots/blotches on leaves.
- Prevention/Control: Good air circulation (proper spacing)! Cut stems at ground level in fall and DESTROY foliage (do not compost). Water at base, avoid wetting leaves. Remove and destroy any infected parts immediately. Fungicides can be used preventatively in early spring if botrytis is a recurring problem.
Conclusion
Peonies are long-lived treasures that bring unparalleled beauty and fragrance to the late spring garden. While they demand patience initially and require careful attention to planting depth (for herbaceous types), they are remarkably resilient and low-maintenance once established. Provide them with sun, good drainage, adequate air circulation, and proper fall cleanup, and these magnificent plants will reward you with breathtaking blooms for decades to come.
