Yard and Garden: Caring for Hostas in Spring


March 23, 2017, 9:22 am | Richard Jauron, Greg Wallace

AMES, Iowa – Spring is here, and hostas are a popular part of outdoor landscaping plans. They are easy to grow, but certain steps in planting and dividing them must be followed in order to ensure optimal performance, including watering and pest control.

ISU Extension and Outreach horticulturists can help answer your questions about how to best handle hostas.

When is the best time to divide hostas?

Spring is the best time to divide hostas. Dig up the entire clump as soon as the leaves begin to emerge. (The emerging leaves are bullet-shaped and are often referred to as points or noses.)  Carefully divide the clump into sections with a sharp knife. Each section should have at least two or three points (leaves) and a good portion of the crown and root system. Replant immediately. 

While spring is the best time to divide hostas, plants can be divided anytime from spring to late summer. Hostas divided in late summer should be mulched with several inches of straw, pine needles or other materials in late fall. Mulching helps prevent repeated freezing and thawing of the soil during the winter months that could heave late summer divisions up out of the soil and damage or destroy them.

Hostas

What are the site requirements for hostas?

Hostas are easy to grow when planted in favorable locations. The most important site requirements are light levels and soil conditions.

Most hosta cultivars perform best in partial to full shade. A site that receives between two to four hours of direct sun per day is partial shade, while a site that receives less than two hours of direct sun per day is full shade. Most of the yellow and gold leafed hosta cultivars develop their best leaf color in areas that receive four to five hours of direct sun.  

Hostas prefer well-drained, fertile soils that contain high levels of organic matter. Soils that contain high levels of clay or sand can be improved by incorporating organic matter (compost, sphagnum peat moss, shredded oak leaves, etc.). In poorly drained sites, the best solution may be to construct a raised bed.

Do hostas need to be watered during the growing season? 

For best performance, hostas need a consistent supply of moisture throughout the growing season. Dry conditions inhibit plant growth and may lead to scorching (browning) of leaf margins. To help conserve soil moisture, apply a 2- to 3-inch-layer of wood chips, shredded bark or other mulch around hostas. Also, water plants weekly during prolonged dry periods.

Should I fertilize my hostas?

Hostas do not require heavy fertilization. A single application of an all-purpose garden fertilizer, such as 10-10-10, in spring as growth begins to emerge is usually sufficient.

How do I control slugs on my hostas?

Several strategies can be used to control slugs. Small numbers can be controlled by handpicking. Handpicking is best done at night with a flashlight as slugs are most active at night. Traps can also be used to control slugs. A trap can be a piece of wood or asphalt shingle. Place the object on the ground where slugs have been feeding.

Lift up the trap after one to two days and destroy any slugs hiding beneath it. Shallow pans of beer also attract slugs. Sink the pans into the ground so the rim is even with the soil surface.  Empty the pans at least twice a week. Pesticides (molluscicides) will likely be necessary to control large slug populations. Slug baits typically contain metaldehyde or ferric (iron) phosphate.  

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