Gardening: Protecting heirloom tomatoes from disease

Nancy Szerlag
Special to The Detroit News

Correction: This story has been updated to correct information about the upcoming Grosse Pointe Garden Tour on June 23-24.

Heirloom tomatoes are all the rage with today’s gardeners because of their superior flavor, but sadly many lack the disease resistance needed to get through the summer. Southern Californian tomato maven Steve Goto (, ( who grows more than 900 varieties of heirloom tomatoes, recommends the use of aspirin to help keep his tomatoes disease free.

Researchers at the University of Florida and the USDA have confirmed that salicylic acid, the active ingredient in common aspirin, activates and boosts the natural SAR (Systemic Acquired Resistance) in plants against bacterial, fungal and viral diseases.

The original formula calls for dissolving 1 1/2 (325 mg) uncoated aspirins in 2 gallons of water mixed with 2 tablespoons of a mild dish soap that acts a surfactant. The surfactant lowers the surface tension of aspirin and water solution so it spreads evenly on the leaves of the plants rather than beading up and sticks to them. An anti-transpirant, such as Wilt-Pruf, is another option. Spraying the plants every three weeks will improve their resistance to disease and insects and also increases their yields. Be sure to hit the undersides of the leaves.

For larger plants, such as tomatoes, Goto suggests inserting 2 aspirins 2 inches deep in the soil, one each on opposite sides of the plant. This treatment will last the entire season.

More is not better as far as the number of liquid applications or aspirins stuck in the soil. Too much salicylic acid may damage the plants. So if you stick the 2 aspirin in the soil, do not use the liquid spray on the tomatoes. And if you use the liquid spray, be accurate with your measurements and timing. Mark the spray dates on your calendar.

Along with my tomatoes, I plan to use the aspirin spray on cucumbers and squash plants. Beans, kale and Swiss chard are also on my list to spray. To prevent sun damage, use the spray at sundown or early in the morning.

This protocol also works on roses and other flowering plants. I’m going to see if this aspirin solution will extend the life of my cut flowers.

Upcoming events: The Grosse Pointe Garden Tour is June 23 and 24.

Nancy Szerlag is a master gardener and a Metro Detroit freelance writer. Her column appears Fridays in Homestyle. To ask her a question go to and click on Ask Nancy. You can also read her previous columns at