Ask the Gardener: Combination planting, slugs, perennials and more

Posted on: August 16, 2019 | Written By: Doug Oster | Comments

Everybody Gardens editor Doug Oster gets asked a lot of questions. A lot. And he doesn’t mind offering gardening advice. But rather than just limiting those answers to the person who asked, we thought it might be a good idea to share that wealth of knowledge with everybody.

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(The questions may be lightly edited for grammar/clarity/etc.)

combination planting

Question 1: Combination planting

Bridgette: I was wondering if I could plant my black elephant ears and my canna lilies together?

Doug: They both like something different. The cannas are sun lovers, and the elephant ears are shade lovers. You might be able to play around and find a spot in the garden though for both. Morning sun and afternoon shade might work. That’s a really beautiful elephant ear.

Question 2: Stopping slugs

Sheila: Slugs have attacked my zucchini plants (again). I have used slug bait and eggshells, to no avail. ? Is there anything I can do to the soil to get ready for next year? I also have spotted tomato leaves but don’t have many options for moving them to another space next year, so can I treat the soil for next growing season?

Doug: Sluggo is my go-to slug bait. It’s organic and will control an infestation. The other product I use is called diatomaceous earth. It is sharp on the microscopic level but needs to be re-applied after a rain. There’s nothing to put in the soil to deal with them. When it’s this wet, we’re going to have slugs. Sluggo has worked wonders in my garden, and you can get it here.

The solution for early blight and septoria leaf spot, the problem you’re dealing with can’t be done by treating the soil. The fungal spores will always be there. The solution right now is to remove the infected foliage and treat with the organic fungicide Serenade (available here). These diseases rarely kill the plant; they just slow it down. There are a bunch of cultural things I do with my plants to avoid those diseases. They are detailed in this story.

Question 3: Perennials over winter

John: This year, I put some perennials in my containers. How shall I treat them over the winter? I have a garage that is always at 50 or above. How often should I water them?

Doug: As long as they are Zone 5, they can stay outside. I would want to move them to a protected spot, close to the house. Maybe surround the pots with a bale or two of straw, too. If you want to bring them into the garage, you’ll probably need to add a little bit of water about once a month.


Question 4: Chemical on tomatoes

Sherri: My neighbor’s tomato plants are on the right, mine are the left. He sprinkled some white powder all over them. I doubt it is organic. Will the fact that his plants are so close to mine harm mine? The worse thing I can think of is that pests will come over to my plants.

Doug: There’s no knowing what he used unless you ask him. The biggest concern is that it’s a chemical pesticide that you wouldn’t want to ingest. I’d do my best to try and keep it on his side of the property line. I would ask him what it is, then check back with me. If it’s what I suspect, it’s nasty. There’s no worry of the bugs coming to your garden, he’s probably killed them on contact.

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