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Jessica Walliser

Off-season preparation key to successful garden

Jessica Walliser
| Saturday, Dec. 31, 2016, 9:00 p.m.
Take steps now to deter diseases in next year’s garden.
Jessica Walliser
Take steps now to deter diseases in next year’s garden.

If your vegetable and flower gardens didn't fare as well as you'd hoped in 2016 due to various plant diseases, plan now to prevent the same from happening again next year.

From blight on tomatoes and powdery mildew on bee balm, to brown rot on peaches and botrytis on geraniums, there are numerous plant diseases that can strike your garden. The good news is that, if you utilize a few preventative measures, you can greatly reduce your risk of encountering these pathogens next year.

First and foremost, good sanitation is key. Because many of these issues are fungal in nature, the spores can easily overwinter on plant debris and fallen leaves. If you know a plant was affected by a disease last year, make sure you clean up all the debris from that plant right now, and throw it into the garbage or burn it. Don't toss fungal infected leaves onto the compost pile. Most home compost piles don't reach a high enough temperature to kill fungal spores, unless you're religious about turning the pile weekly.

Diseases can also overwinter on infected fruits, so if you're a fruit grower, make sure you remove any fallen fruit or fruit left clinging to the branches and dispose of it as mentioned above.

A second aspect of good sanitation is to clean your gardening equipment. Because many pathogens can live on digging and cutting tools and spread from plant to plant via pruning, sanitize all pruners, saws and other equipment with a spray disinfectant or a 10 percent bleach solution before the start of next gardening season. Throughout the gardening season, every time you use equipment to prune a plant that's affected by a disease, whether it's black spot on your roses or septoria leaf spot on tomatoes, that piece of equipment should be disinfected before using it on another plant.

Another great way to reduce the chance of disease striking your garden is to limit environmental stress. Many diseases are more likely to develop when a plant is stressed and not thriving. Weak plants are more susceptible to diseases, so test your garden soil to make sure your plants have all the nutrients they need (but don't overfertilize!), and ensure they have ample water throughout the growing season.

Because many fungal diseases are more prevalent when moisture levels are high, gardeners should also take a few measures to promote good air circulation in the garden. Don't crowd plants and make sure each one has more than enough room to grow.

Prune out crossing branches to improve air flow through fruit trees, tomatoes and other disease-prone plants. Also, avoid working in the garden when the foliage is wet. Fungal spores can spread from plant to plant on water droplets clinging to your clothes or skin.

Carefully inspect all new plants for signs of disease before introducing them to your garden next year. Purchase your plants from a good, local nursery and pay sharp attention to making sure you plant only varieties with noted resistance to diseases.

Crop rotation is another key to disease prevention, especially in the vegetable garden. Even if your garden is small, moving the plants over a few feet from where they were can make a difference.

Don't follow a plant from a certain family with another plant from the same family for two subsequent growing seasons.

And finally, mulch your garden immediately after you plant it. Since many fungal diseases are soil-borne, putting a protective layer of mulch between the plant and the soil keeps the spores from splashing up onto the foliage when it rains. For the best results, put mulch down over the soil immediately after planting, even before you water the plants in. This is of particular importance in the tomato patch where early blight and septoria leaf spot can easily spread to plants via spores in the soil. Right after planting, cover the soil with shredded leaves, straw, untreated grass clippings, high-quality compost or another type of mulch (I don't suggest shredded bark as it's not the best mulch for vegetable gardens).

If you're a container gardener who was faced with diseases last season, completely empty the potting mix in all your containers and sanitize the pots with a 10 percent bleach solution. Dispose of the old potting soil and replace it with new potting mix prior to planting next spring.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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