The hostas under my bird feeder have been decimated. Is there another plant that I can use under the feeder?
— Rebecca Gunderson, Elk Grove
We have bird feeders at home located over a mixed planting of shrubs and perennials and have had good luck growing plants near the feeder. Your question does not include the type of seeds you are using in the feeder. Sunflowers are a favorite food of songbirds and are present in many commercial seed mixes. Sunflower seed hulls contain a toxin that inhibits growth in some plants so the sunflower hulls that fall to the ground under the feeder can impact plants growing there. This process is called allelopathy, which refers to the release of chemicals by one plant that affect another plant. These chemicals can be given off by different parts of the plant or released by natural decomposition. Allelopathy is a survival mechanism that allows certain plants to compete with and sometimes destroy nearby plants by inhibiting seed sprouting, root development or nutrient uptake. Black walnut is another example of a plant that will inhibit the growth of many plants growing near it. Your problem may also be caused by chipmunks and squirrels eating the seed that falls to the ground and trampling plants in the process.
Consider using a high-quality bird seed in your feeder since you may be using a seed mix that has filler such as oats, barley or red millet that birds choose not to eat and end up on the ground attracting animals. Try a “no mess” blend in which seeds do not have shells and are cut more in pieces to reduce waste. There are seed mixtures that do not contain whole sunflower seeds or use hull-less sunflower seeds to eliminate the toxin problem. Whichever seed mix you use there will likely be some seeds that drop to the ground and germinate requiring an occasional hoeing to control. Also, it is a good idea to periodically clean up the old seeds and hulls that collect on the ground. The advantage of some open ground under the feeder is to attract ground-feeding birds such as doves. Some birds will use the bare ground to take a dust bath to maintain their feathers.
Not every plant is affected by the allelopathic properties of sunflower hulls so experiment with different varieties until you find a combination that works for you. If the plants you try show stunted growth, leaf wilting, yellowing leaves or just fail then likely the bird seed mix is affecting your choice. Some plants to start with would be annual sunflowers — use low growing types, Rozanne geranium (Geranium ‘Rozanne’), creeping lilyturf (Lirope spicata), cranberry cotoneaster (Cotoneaster apiculatus), mint and black-eyed Susan (Rudbeckia hirta). Install plants that spread like yellow archangel (Lamiastrum galeobdolon ‘Variegatum’) around the edges of the bare zone so that the plants can creep into the area under the feeder. Mints are very aggressive spreaders and will move into adjacent areas.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
