Bartzella Itoh Peony

Overview

Bartzella is an Itoh (intersectional) peony, a hybrid that crosses a herbaceous peony with a tree peony to combine the best of both (Paeonia 'Bartzella'). It is prized for enormous lemon-yellow, lightly ruffled blooms with a soft red flare at the centre, carried on sturdy stems above deeply cut, tree-peony-like foliage. Unlike old-fashioned garden peonies, its strong stalks rarely flop, so the flowers stay upright even after rain.

Origin & Background

The genus Paeonia is native across the Northern Hemisphere, with species in the mountains and woodland edges of Europe, western North America, and especially China, where tree and herbaceous peonies have been cultivated for centuries. 'Bartzella' itself is a modern intersectional hybrid raised by American breeder Roger Anderson and introduced in the late 1980s, following the pioneering intersectional work of Toichi Itoh in Japan. It went on to win the American Peony Society Gold Medal, cementing its reputation as one of the finest yellow peonies available.

Appearance

The flowers are large, often 6 to 8 inches across, semi-double to double, in a clear soft yellow with a small raspberry-red blotch at the base of the inner petals. Blooms open in late spring to early summer and carry a light, fresh, lemon-like scent. A single established clump produces many buds that open in succession, extending the show. The plant forms a rounded, shrubby mound roughly 2.5 to 3 feet tall and about 3 to 4 feet wide, with glossy, dark green, finely divided leaves that stay attractive through summer and take on bronze tints before dying back in autumn.

Why People Grow It - Qualities & Benefits

• True yellow flowers, a colour that is rare and hard to find among peonies
• Strong, self-supporting stems that seldom need staking
• Long bloom period thanks to many buds opening in sequence
• Handsome cut foliage that looks good long after the flowers fade

Care

Light: Full sun is best (at least 6 hours daily); light afternoon shade is tolerated in hot regions and can help flower colour last. Water: Moderate and even moisture while establishing; once settled it is fairly drought tolerant and dislikes waterlogged soil. Soil: Fertile, deep, well-drained loam with a neutral to slightly alkaline pH (about 6.5 to 7.5); enrich with compost at planting. Hardiness: USDA zones 4 to 9. Bloom or Season: Late spring into early summer, with the display typically lasting 2 to 3 weeks as successive buds open. Extra: Itoh peonies die back to the ground each winter like herbaceous types, so cut old stems down in late autumn. Note for pet owners: peonies are toxic to cats and dogs, containing paeonol concentrated in the bark and roots, and ingestion can cause vomiting and diarrhoea.

Planting & Propagation

Plant dormant roots in early autumn so the eyes (growth buds) sit only about 1 to 2 inches below the soil surface; planting too deep is the most common reason peonies fail to bloom. To propagate, lift the tuberous root mass in early autumn and divide it with a clean, sharp knife into sections that each carry 3 to 5 healthy eyes and a good piece of root. Replant divisions promptly at the correct depth and water in. Growing from seed is possible but very slow and will not come true to the parent, so division is the reliable method; expect a year or two before divisions bloom well.

Common Problems & Pests

• Botrytis (grey mould) in cool, wet springs, causing blackened buds and stem rot; improve airflow and remove affected growth
• Failure to flower, almost always from planting the eyes too deep or too much shade
• Occasional nibbling by deer, plus minor ants on buds (the ants are harmless and need no control)

Toxicity & Safety

Peonies are toxic to cats and dogs. They contain paeonol, a compound most concentrated in the bark and roots, and chewing or swallowing plant material can cause vomiting and diarrhoea. Symptoms are usually mild to moderate, but it is sensible to discourage pets from grazing on the plant and to be especially tidy with root pieces during autumn division. If you suspect your pet has eaten a significant amount, contact your veterinarian.

Pros & Cons

Pros

• Rare, dependable yellow colour on a robust, low-maintenance plant
• Sturdy stems and long-lived clumps that improve with age

Cons

• Toxic to cats and dogs, so not ideal where pets graze freely
• Slow to bulk up and relatively expensive to buy compared with common peonies

Best Suited For

• Gardeners wanting a standout yellow flowering shrub-like perennial for a sunny border
• Cold-climate and low-fuss gardens where a reliable, self-supporting peony is valued

FAQ

Does Bartzella need staking like other peonies?

Usually not. One of its main advantages is thick, strong stems inherited from its tree-peony parent, so the heavy blooms typically stay upright without rings or supports.

How long until a new plant flowers well?

Give it patience. A young division may show a few blooms in its first year or two, but Itoh peonies really hit their stride around the third season, after which the clump grows fuller and flowers more freely each year.