As a decorative garden plant, hostas have become a very popular choice. They are winter hardy, easy to propagate and both their flowers and foliage have terrific visual appeal. However; like all plants, hostas can develop problems. If the leaves on yours are developing brown spots, there may be several forces at work. They might be environmental in nature, or the result of plant pathogens. Here are some potential causes and remedies.
Hostas are shade loving plants that are not heat tolerant. They fare best when they receive the cool morning sun and the deep shade of the afternoon. The brown leaves appearing on your plants may be caused by too much hot direct sunlight. If possible, you might dig up the plants and move them to a more suitable location. If it is too late in the growing season to attempt this, perhaps you could find something to shade them with and move them in the spring before the new growing season begins in earnest.
For proper growth and development, hostas require regular watering. The experts at Ohio State University recommend that hostas receive a minimum of one inch of water per week. The leaves on your plant may have dried and died due to a lack of water. If you are watering your plants regularly, you may need to water them more often. Water them in the morning, so the warm afternoon air does not cause excessive evaporation before the moisture reaches deep into the soil. If your soil is sandy and drains too quickly, you may need to apply extra water or improve the soil by adding organic material.
Hostas must be very tasty, because they are attacked by a variety of garden pests. Slugs and snails chew on the leaves and damage them to the point when they turn brown and die. Black vine weevils and nematodes also feed on hosta leaves and will cause leaves to wilt and dry. Slugs and snails are the most common enemies of hostas and can be eradicated with the use of chemical pellets which are scattered on the ground surrounding the plants.
If the foliage of your hostas was exposed to a late spring frost, the brown leaves are probably an indication of frost damage. Unless the entire plant has frozen and turned brown, it will probably recover on its own. Until all danger of frost has passed, you may need to cover the plants on especially chilly evenings.
Several viruses and fungi have recently begun attacking hosta plants. Some chemical treatments have been developed, but none have proven to be completely effective. Contact your local agricultural extension service for advice and suggestions. However; if your plants have been severely infected, your only choice may be to dig them up and discard them. Good luck dealing with your hosta problems.