Remedies for sick, insect-ridden and sad hostas

Something been nagging your hostas? With a wide range of culprits, from insects to fungus and woodland creatures, you have your work cut out for you. But with these tips, you and your hostas have a fighting chance.

Hostas are relatively trouble-free when properly positioned and growing in good soil, but they do have occasional problems and should be regularly checked for the first signs of trouble.

• Cause: Deer or rabbits
• Control: Other than surrounding the garden with a tall fence, deer control is very difficult. For rabbits, surround plants with a fine wire mesh buried into the soil and 90 cm (35 inches) high.

• Cause: Slugs and snails
• Control: Difficult to control completely, check solutions in the list below.

• Cause: Vine weevils
• Control: Repot into fresh soil, look for white grubs in old soil and kill them. Adults eat foliage, spray with insecticidal soap.

• Cause: Crown rot (fungus)
• Control: Dig up plant, scrape away all diseased tissue, dust with sulphur and replant in fresh location. More common where summers are hot and humid or in poorly drained sites.

• Cause: Leaf spot (fungus) or frost or sun damage
• Control: Spray with fungicidal soap. Protect new growth in spring from late frosts. Do not water overhead in bright sunlight.

• Cause: Virus
• Control: Slow to appear, it can take several years for a plant to show symptoms. Spreads easily when dividing, removing blooms, passes from hands or knife blade. Dig up infected plants and destroy. Do not plant hostas on same site for 2 years.

The chief enemy of hostas are slugs and snails, especially the small ones that are hard to find. They come out at night and eat holes in the foliage, leaving it lacelike after a few weeks.

Some varieties are more resistant to damage than others and those with thick, crinkled leaves are less likely to be damaged than those with thin soft foliage.

• Control is difficult. Hand pick at night with a flashlight, dropping them into a can of insecticidal soap or light oil. Shallow containers buried to their rims in the soil and filled with beer attract and kill both pests.

Small plants can be protected by putting a ring of diatomaceous earth around them, but it needs to be replenished after rain or watering.

• If only a few plants are involved, an evening patrol with a spray bottle containing a 10 per cent ammonia solution works well. You should spray the soil under the plants, and onto the bases of the leaf stalks. Ammonia is a source of nitrogen and at this concentration does not burn plants, but kills slugs and snails.

• 'Big Daddy'
• 'Blue Angel'
• 'Blue Cadet'
• 'Blue Umbrellas'
• 'Bold Ruffles'
• 'Christmas Tree'
• 'Frances Williams'
• 'Fringe Benefit'
• 'Gold Edger'
• 'Gold Regal'
• 'Green Fountain'
• 'Green Piecrust'
• 'Green Sheen'
• 'Green Wedge'
• 'Krossa Regal'
• 'Midas Touch'
• 'Pizzazz'
• 'Sea Drift'
• 'Spritzer'
• 'Sum and Substance'
• Tokudama (and forms)
• 'Zounds'