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By Walter Reeves, For the AJC

Troy Warren #homegarden-all

Q: Are used coffee grounds a good additive for our acidic soil? Julie Wright, email

A: Coffee grounds are a good soil additive, like any kind of organic material. Once completely broken down, they open up the soil and hold nutrients and water. It is a myth that they are acidic or problematic in any way.

Q: I planted two weeping cherries in the 15-gallon size. I am wondering if I should use fertilizer spikes on them. Name withheld, Woodstock

A: My advice is to avoid fertilizer for the first year after planting a new tree. The roots need that time to explore the soil. Fertilizer will encourage new leaf growth, which will stress the roots this summer when it’s hot. If you want the two trees to grow larger, you could fertilize once or twice each year after this first one. I would rather you use an evenly applied general purpose landscape fertilizer rather than spikes. Alternatively, you could spread fresh arborist wood chips in a 6-inch layer around each tree now. The chips will prevent weeds and provide nutrients as the trees grow. Replenish the chips as needed.

Q: I have a lovely bed of old and established iris. Unfortunately, I have allowed it to get infiltrated by liriope and mondo grass. How can I get rid of them? Mickey Baskett, email

A: It is almost impossible to get rid of these two intruders selectively in a flower bed. You’re going to have to dig up the whole bed, save the iris roots, and use the resulting dirt in a less problematic spot. Then you can fill the bed with clean, high-quality soil and replant the iris. While you’re at it, remove and discard any rotten or dried-out roots. There is no need to clip the foliage into a fan. As long as it’s green, the iris needs it for photosynthesis.

Q: Several years ago, my husband and I were given two extremely large concrete pots, which we put in full sun in our backyard. I have read that lime from concrete can be problematic for some plants. What would grow well in this type pot? Alice Newman, Jefferson

A: I don’t believe there will be any problem with soil pH being affected by the lime in the concrete. After just a year or two, any lime that’s present has been dissolved and washed out. Recently, I saw a container like yours that had an upright topiary rosemary in the middle. It was surrounded by pansies at the base. You could do something similar for the summer and use spreading petunias for color.

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