Ask the Gardener: Dahlias, rose of Sharon, soil improvements and more

Posted on: August 23, 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.

There are three ways to send in your questions:

  • Email
  • Submit your question on our “Your Garden” section of our site
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(The questions may be lightly edited for grammar/clarity/etc.)

Question 1: Dahlias

Lorraine: Some of the dahlias I planted this year have grown tall and bushy but with blooms on stubby little stems 2 to 4 inches long, too short to cut for a flower arrangement. Other dahlias aren’t bushy at all but have just one or two very thick, very tall sturdy stems with only one or two buds at the top. Do you know what would cause these problems?

Doug: These problems are nothing to worry about as there’s nothing you can do about them. Each variety of dahlias will bloom differently and present the flowers in their own way. The weather will also affect how the plants bloom. Enjoy the flowers as they are. Don’t forget, dahlia tubers can be saved over the winter indoors if you’re interested.

Question 2: Rose of Sharon struggles

Ray: About four weeks ago, I planted 30 rose of Sharon plants in the backyard to make a privacy hedge. On five of the plants, a quarter of the leaves are turning yellow and falling off, making those five look thinner. All other plants are really healthy. Any thoughts?

Doug: All you can do is make sure they have the water they need. The good news is that rose of Sharon is almost indestructible. I would assume they will come back when things cool off.

Question 3: Improving soil

Dianna: Several years ago I got cow manure from a local farmer. He told me the manure was over one year old and not hot. I was very excited thinking my garden is going to love this. Well, my garden did horrible that year and has gone downhill ever since. I have the soil tested every year. The PH level is off the chart so I was told to put Urea fertilizer on it, and I followed the instructions they had given me. I did OK last year but had it tested again with the same results. So, again I used the Urea. This year is probably the worst year I have had. My tomatoes are barely growing; my lima beans are all plant and flowers but NO BEANS. And zucchini plants are huge but not one zucchini. I need all the help I can get.

Doug: Fertility and pH are critical to healthy plants. The Urea will help the fertility, but you need to address the pH issue. Take a look at the soil test and see what they recommend for the pH.

One thing to do while you are working on correcting the pH would be to grow in straight compost. It’s usually very close to 6.5 pH and has all the nutrients the plants need. When I have an area that’s not doing what it’s supposed to do, I dump a few bags of compost and I’m ready to go.

bug identification

Question 4: Bug ID

Delaney: I have these swarming a few of my tomato plants and my only artichoke plant (which is precious to me). Does anyone know what they are and the best way to get rid of them, or if they’ll harm my plants at all? Any help would be appreciated. I have neem oil right now, but I don’t know if it works on bugs like these.

Doug: I think it’s a young stink bug. The only thing I know to do is flick them into some soapy water.

Question 5: Deadheading

Frauke: When should I stop deadheading echinacea, liatris and sunflowers to keep seeds for birds or pollinators?

Doug: Right now … let them grow for the rest of the season to help the birds.

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