Hostas a hardy perennial for Colorado gardens

Colorado State University
Extension Master Gardener

Hostas are extremely popular hardy herbaceous perennials grown primarily for their beautiful foliage. They are easy-to-grow, shade-tolerant plants. Leaves come in a wide range of shapes, colors, sizes and textures and may be a solid color or variegated. Plants are low-maintenance and are widely available in nurseries and garden centers.

Many catalogs also offer a large selection of hosta plants, with more than 2,500 different cultivars on the market.

Hostas originally came from Japan, China and Korea. First introduced to Europe in the late 1700s, hostas came to the United States in the mid-1800s.

A hosta plant generally reaches full maturity in four to eight years. The size of the plant depends on the cultivar. Cultivars are cultivated varieties that have been developed for a desirable or improved feature such as plant form, size, bloom, leaf color, variegation or pest resistance.

The size of hosta varies from only a few inches in diameter to over eight feet wide, sometimes even larger. Most hosta plants develop a rounded shape. Some cultivars have a vase shape, which is maintained as the plant grows larger.

Hosta leaves may be a solid color such as blue, green, gold or yellow. Variegated leaves may include a combination of lighter and darker shades of color in the leaf. Some plants show seasonal foliar change. Leaf color may also be affected by the amount of sun the leaves receive.

All hostas bloom in summer with spikes of lavender to white, lily-like flowers, which can be quite showy and fragrant. New cultivars of hosta plants are also being bred to produce larger and even more attractive flowers. Some plants bear 50 to 75 blooms on each flower scape.

Hostas are considered shade-tolerant plants, but most do not thrive if grown in deep shade—especially if conditions are dry. Hostas grow best in an exposure with morning sun and afternoon shade. Some cultivars will tolerate some afternoon sun.

In general, the blue-leafed hostas require shade, while the gold-, yellow- and white-leafed hostas can tolerate more sun. Fragrant hostas grow best with five to six hours of daily sun.

Plants grow best in rich organic soil. Unless you have ideal soil, you will need to add organic amendments. The recommended soil is well-drained, enriched both with nutrients and organic matter. The ideal pH for hostas is 6.5 to 7.5, which is slightly acidic to slightly alkaline.

The planting hole should be dug at least a foot deep. The width of the hole should be one and a half times the expected mature size of the clump.

Check the plant’s label for ultimate size. Most hosta roots will grow and spread horizontally, so a large, wide hole is best.

Remove the plant from its container and loosen and untangle the roots. Shake excess soil from the roots. Place the plant in the hole at the same level as it grew in the container. The area where the leaves and roots meet should be at ground level.

Hostas ordered from mail-order catalogs may arrive as bare-root plants. Soak the roots in tepid water for about 30 minutes prior to planting. Form a small cone of soil at the bottom of the hole, spread the roots over it and add the amended soil. Water plants well following planting.

Some gardens do not need additional fertilizer if a soil test shows the soil has sufficient amounts of the necessary nutrients. In this case, an addition of compost over the bed once a year, applied in the fall, is usually sufficient.

Water is important for optimal growth. A minimum of an inch of water each week is recommended. Watering hostas on a regular basis early in the day is highly recommended. Deep watering will ensure good root development. Occasionally, a plant will show symptoms of inadequate water. Leaf tips may burn, and drooping leaves may be caused by inadequate moisture.

Propagation of hostas is easily achieved by dividing existing plants. Hostas do not come true-to-type when planted from seeds. Most home gardeners propagate hostas by division. Although spring division is easiest, summer division is preferred and can be done in August, at least 90 days before the first fall frost date. To divide, dig the entire plant from the ground and using a sharp shovel or knife, separate it into smaller sections. Replant one division in the existing hole and plant the others in your landscape or share with friends.

Slugs and snails are nocturnal foragers and are the most common pests of hostas. They eat small round holes in the leaves. Thin-leafed hostas and those with leaves close to the ground are most susceptible to slug injury. There are baits you can put out to capture slugs; other gardeners have found success using shallow containers filled with beer. Place saucers or lids of beer in shallow depressions in the ground about 10 feet apart. Make sure the lid’s edge is at ground level and be sure to empty the traps each morning.

Hostas are a versatile and colorful plant for Colorado landscapes. Their large leaves and colorful foliage brighten up shady parts of gardens—leaves can even be used for cut flower arrangements. Once you plant a few, you may be hooked on finding new and different plants to add to your shade gardens.