Ivy is an easy plant to keep. It tolerates a wide range of soil types, climates and lighting conditions. Most of the problems that can cause ivy leaves to turn yellow are caused by pests that like to live on the plant. Improper care, however, can also cause ivy to turn yellow and drop leaves.
Spider mites and English Ivy seem to go hand in hand, but the pests can attack any type of ivy as well as other houseplants. An infestation is difficult to see, but small webs may be present and the spider mites may appear as red or dark dots on the underside of leaves. They can cause leaves to turn yellow, curl and die. Move an infested plant away from other plants. To treat for spider mites, trim off any dead or diseased parts and coat the entire plant with an insecticide soap spray. Make homemade soap spray by mixing 1 tsp of liquid dish soap with one quart of water. Commercial sprays are also available. Mist the entire plant thoroughly, as the soap must come in contact with the spider mites to be effective. Prevent spider mites by inspecting plants closely prior to purchase, and misting the ivy plant regularly with water to discourage the pests. Spider mites prefer dry, warm environments. Outdoors, you can use ladybirds to control spider mites.
Lack of sunlight and proper nutrients can cause ivy to lose its colour and turn yellow. Make sure your ivy is receiving enough sun by keeping it near a south or west-facing window. Outdoors, check to see if large trees or other objects are blocking too much of the light. Fertilise potted ivy regularly, about once a month, with an all-purpose indoor plant fertiliser, as the soil is not naturally replenished with nutrients. Feed outdoor ivy plants once in the spring with an all-purpose outdoor fertiliser. Fertilise them again in the fall if the plants are stressed, but most outdoor ivy plants only require one annual feeding.
Like spider mites, aphids can quickly damage ivy and cause the leaves to turn yellow. While most aphid infestations occur on outdoor ivy, but they can also occur indoors when an infected plant is brought inside. Check the underside of the leaf for clusters of tiny green, yellow-green or brown aphids the size of a pin head.
Spray an indoor ivy with an insecticidal soap, using the same method as treating for spider mites. Like spider mites, aphids must come in contact with the soap for the treatment to be effective. For light infestations, remove the infected area or rinse the entire plant with water in a sink or bathtub. Outdoors, spray ivy with water, soap spray or an insecticide to remove small infestations. Ladybirds also control aphids.
Scale actually refers to a pest, not a virus or other infection. Similar to aphids and spider mites, scale attaches to ivy plants and damages leaves. Yellow leaves are the first sign of an infection, but eventually, entire portions of the plant die. Scales appear as small bumps, usually yellow or brown, but sometimes white or black, on any part of the plant. Remove any dead or heavily damaged areas of the plant. Spray indoor ivy plants infected with scale, using an insecticide soap or a horticultural oil. Make a homemade oil spray by combining 1 tbsp canola or vegetable oil and 1 tsp liquid dish soap in 1 quart of water. Apply in the same way as directed for spider mites. Treat outdoor ivy plants with soap or oil spray, or with a commercial insecticide.