For showy, colorful flowers, it's hard to beat peony (Paeonia spp.) and ranunculus blossoms (Ranunculus spp.). The several types of ranunculus plants include lesser celandine (Ranunculus ficaria) and the creeping buttercup cultivar 'Buttered Popcorn' (Ranunculus repens 'Buttered Popcorn'), which grow as perennials in U.S. Department of Agriculture plant hardiness zones 4 through 8 and 4 through 9, respectively. Persian buttercup (Ranunculus asiaticus), however, is the most commonly cultivated type of ranunculus.

Persian buttercup and peonies have flowers in dozens of colors, making a vivid splash in a garden bed, and both grow as perennials in certain parts of the United States. These plants, though, have some differences. If you take those different features into account when planting, then both peonies and Persian buttercups can fill your garden with color.

Growth Habits and Flowers

Persian buttercups and most peonies are called herbaceous perennials because they die to the ground each year when winter arrives. Despite that similarity, they don't share growth habits and have distinctly different blooms.

Ranunculus

Each Persian buttercup grows from a bulblike structure called a tuber that resembles a many-fingered claw. Large tubers produce plants with the greatest number of flowers. The plants can withstand some frost, growing year-round in mild-winter areas in USDA zones 8 through 11. Tubers planted in fall usually flower in early spring, while planting in spring produces flowers in summer. Persian buttercups also do well in containers or grown as annuals in colder areas.

Persian buttercup grows as a mound of foliage 6 to 12 inches wide, with flowers appearing on its erect, 12- to 18-inch-tall stems. Most varieties have 3- to 6-inch-wide, double flowers with many layers of petals closely arranged in a circle. The flowers come in many colors, including yellow, orange, pink and red.

Peonies

Peonies grow from thick roots, also called tubers, but the peony plants use them to store nutrients; so they're usually much larger than ranunculus tubers. Peony plants come in a number of types, but all are quite cold-hardy, growing as perennials in USDA zones 3 through 8, with some zone variation among varieties. Although many die to the ground in fall, one type, called a tree peony (Paeonia suffruticosa), becomes a woody, deciduous shrub up to 5 feet tall; it is hardy in USDA zones 4 through 8. Plant a peony in either spring or fall, but fall-planting is best because it gives the plant time to put out new roots that help it get a good start in spring when warmth returns.

Peony flowers come in dozens of colors and in many types, including single, semi-double and fully double blossoms. A cultivar called 'Beautiful Senorita' is an example that has a double row of deep-pink petals surrounding a fluffy, yellow-cream center; it is hardy in USDA zones 2 through 8. Peonies are also useful as foliage plants after their flowering ends.

Cultural Needs

Both peonies and Persian buttercups prefer a spot that gets full sun, and both grow in any type of garden soil, provided it's well-drained. For both plants, a site that's constantly soggy can promote root rot and might kill the plants.

Ranunculus

Plant Persian buttercup tubers about 1 or 2 inches deep, and allow 8 to 12 inches of space between large tubers -- called jumbos -- and 4 inches between smaller tubers. They don't require fertilizing and need no special care, but water the plants whenever the top 1 to 2 inches of their soil feels dry to the touch to keep them growing.

For container-growing, set tubers in moistened commercial potting soil, using a container with at least one bottom drainage hole. Choose a 10-inch-diameter pot for two jumbo tubers or three smaller ones. Keep the pot in a sunny spot and, once flowering ends, leave the foliage on the plants until it dies back; doing so allows the plants to store nutrients for the next growing season.

Peonies

Peonies benefit from addition of 1 cup of bonemeal -- a source of calcium -- into the soil at the bottom of their hole at planting time. Like Persian buttercups, peonies don't require regular fertilization, but you can support good growth by sprinkling a handful of bonemeal around the base of each peony plant in midsummer, after blooming ends.

Peony blossoms can be large and might droop to the ground after rain, especially on a herbaceous type. Prevent that situation by using a three-legged ring support around each plant; set it in place early, before new growth appears in spring.

It's important to keep peony root buds -- called eyes -- no deeper than about 2 inches below the soil line. Because of this depth requirement, don't use a thick mulch under the plants; as mulch breaks down, the eyes can become progressively deeper, which might interfere with blooming.