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Why are my violet blossoms white?

Changes in soil pH can affect the color of violets. Some violets become more purple when the soil is more acidic.

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Changes in soil pH can affect the color of violets. Some violets become more purple when the soil is more acidic.

WHAT TO DO THIS WEEK Plant peppers, melons, squash, pumpkins, cucumbers, eggplants, tomatoes, corn, broccoli, and cauliflower. Try to finish planting annuals and container gardens. Cut roses for bouquets just above a branch of outward facing leaflets, so you are pruning the bush while you harvest. Trim asters, mums, and phlox back halfway to encourage bushiness. Stake tall perennials. Harvest berries in the morning after the dew has evaporated. Do not wash the berries until you are ready to use them. When gardening, wear a hat and sunscreen. In deer country, tuck pants into socks and spray ankles with DEET.

Q. Glad to see you are back in the Globe. My question is about violets. I have a large bed of them that are thriving, but for the past few years the blooms have been white. How do I bring back their purple color?

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A. The cause could be a change in soil pH. Perhaps they are growing near a lawn that has been spread with lime to raise the pH. Like hydrangeas, some violets become more purple when the soil is more acidic. Two materials commonly used for acidifying and lowering the soil pH are aluminum sulfate and sulfur, both of which can be found at garden supply centers. Aluminum sulfate will change the soil pH instantly, while sulfur may take a few months to do the trick. Follow label instructions to lower the soil by 0.5, which is only a small change. Too big a change could kill the violets! Wash off plant leaves after application. If this does not work, there could be other reasons for the color change, such as the crowding out of the original purple violets by their own progeny that did not breed “true.” So another tactic is to plant more purple violets, preferably in a new location and away from the lawn.

Q. I have tried to grow cucumbers on my chain-link fence as well as in pots on my deck. Everything starts out great, but then this mold or fungus develops that turns the leaves brown and kills them. I have heard that spraying soapy water on the leaves will help. Is this true or do you have other suggestions?

A. This is a good time of year to plant cucumbers, but they can fall victim to many pests and diseases. If yours died from mold or fungus or anything else last year, grow them in a different location and plant something else on that lethal spot by the chain-link fence for the next three years before trying cucumbers there again. This is called crop rotation, which helps deter pests and prevents disease buildup.

If you plant in pots on your deck, scrape out and spread the old soil over your lawn where it will help feed the grass, soak the pots in a solution of 9 parts water to 1 part bleach to kill diseases, and then refill them with purchased soilless potting mix, which won’t contain pathogens. If you want a long harvest, plant a few new cucumbers every two weeks through mid-July.

Please send your garden questions to Carol Stocker at stockergarden@gmail.com and include your name or initials and your town.
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