Interest in organic gardening is higher than ever but so is confusion over exactly how to accomplish it. How do you provide the nutrients plants need to survive? What can you do about insects and plant diseases? Are some plants too difficult to grow organically in our climate? The answers to some of these questions may surprise you.
The organic challenge
A basic definition of organic gardening is gardening without synthetic fertilizers and pesticides. But organic gardening is much more than simply replacing manmade chemicals with those derived from natural sources. It is a philosophy of gardening that supports the health of the whole system. In an organically managed yard or vegetable garden the emphasis is on cultivating an ecosystem that sustains and nourishes plants, soil microbes and beneficial insects rather than simply making plants grow.
Creating this ecosystem begins with improving the soil. Adding organic matter by mixing compost into the soil increases its capacity to retain water and nutrients and supports beneficial microbes, which are essential to healthy plant growth. Compost can be made at home from grass clippings, leaves, yard debris, and kitchen scraps, or purchased from garden centers and mulch suppliers. Because of the many turkey farms in our area, turkey compost is the most readily available commercially made compost in our region. Another way to add organic matter to the soil is to grow cover crops and turn them into the soil just as they begin to flower. Cover crops that can be seeded at this time of year include buckwheat, cowpeas, millet, and soybeans.
While compost and organic matter will increase your soil’s ability to hold nutrients, they do not supply large amounts of nutrients themselves. In addition to compost, organic gardeners also have to provide fertilizers derived from natural sources such as animal manures and byproducts, natural deposits such as rock phosphate, and plant products like seaweed and wood ash. Most retailers that carry garden supplies also stock organic fertilizers, which can usually be distinguished by their earthy smell.
Another natural product often added to soil is agricultural lime. Made from naturally occurring limestone, lime is used to raise soil pH if your soil is too acidic. Soil pH levels vary tremendously in our area and many soils do not require additional liming. To find if your soil needs additional lime to support healthy plant growth submit samples to the NC Department of Agriculture’s soil testing lab. Boxes and forms are available from your local Extension center.
Natural pest control
Organic gardeners have realistic expectations when it comes to insects and diseases. They don’t try to eliminate all pests from their yard or garden. Instead they seek to keep pests below damaging levels. One of the main methods for keeping pest populations below damaging levels is to encourage thriving populations of beneficial insects and pest predators, including spiders, bats, birds, lizards, and toads. The two most important things you can do in your yard to support these helpful species is to plant a wide variety of plants and flowers and avoid using synthetic pesticides, which more toxic to pollinators and beneficial insects than to pests.
Practicing good sanitation is another method of organic pest control. Removing disease infected leaves or plants, rotating crops so you are not growing the same type in the same spot year after year, and handpicking insect pests and eggs help to suppress pest populations.
In addition to cultural control methods, organic gardeners also use sprays to manage plant pests. Several natural pesticides that control insects and diseases are available from local garden centers. Natural products for pest control include neem oil, insecticidal soaps and oils, and minerals like copper and sulfur. Which product to use will depend on your problem so be sure to have any plant problem properly diagnosed before treating.
There are some diseases and insects that just cannot be controlled organically, making some plants much more challenging to grow organically. While most herbs and landscape plants can easily be cared for organically, some fruits and vegetables cannot. Tomatoes, squash and peaches are the most difficult crops to grow without synthetic pesticides in our region, while figs, blueberries, watermelons, peppers, and eggplant are among the easiest.
To learn more about soil testing, pest identification and natural fertilizers and pesticides, visit ces.ncsu.edu where you can submit questions via the ‘Ask an Expert’ link, or contact your local Cooperative Extension center: In Pender County, call 910-259-1238; in New Hanover County, call 910-798-7660; in Brunswick County call 910-253-2610.
Charlotte D. Glen is the horticulture agent with the Pender County Cooperative Extension of NC State University, College of Agriculture & Life Sciences. She can be reached via e-mail at Charlotte_Glen@ncsu.edu.