Ask John

BearTools_Fotor If you have a question about gardening in the Birmingham area, ask John. John Floyd has been gardening–and learning about gardening–for more than 30 years. In addition to his day-to-day experience in the garden, John has degrees in horticulture, plant taxonomy, and plant physiology from Auburn and Clemson Universities and was Editor-in-Chief of Southern Living.

If you need to include a photo, you can email your question to BirminghamGardeningToday@gmail.com


As my hydrangeas are beginning to turn green, I’ve noticed many branches with no new growth. Do I need to trim these at the base? How do get them looking healthy again? 3. April 2015

hydrangea leafing out

What one of my bigleaf hydrangeas looks like in my garden. Not ready to be pruned, yet.

Take a look at “Tending the Garden – March 26,” and you will see my thoughts on your hydrangeas. I usually do not prune any stems off mine until late April when I am sure they are dead, because the flowers bloom off the shoot that develop from the old stems.



I am enjoying the blue pansies and blue Siberian Iris. What is the best time of the year to plant for April enjoyment? 3. April 2015

I always plant pansies in late fall, generally right after the first frost. As for siberian iris, they are tough and can be planted now, as they are just beginning to put up their new foliage. But I think most folks think with iris, the earlier in spring the better. IF you did not put your pansies in last fall, it is too late now, as we are thinking about summer annuals. If you are enjoying blue iris now, it is probably Dutch iris. These are bulbs that need to be planted anytime in this area from November through early January.


With things like my snowball hydrangeas already trying to bloom, is there anything I need to be sure and cover this weekend given the chance of frost? 28. March 2015

I want to answer this in two ways. If the temperature does not fall below freezing a prolonged length of time, the shrubs and trees will probably be all right or only suffer a slight bit of damage. On the other hand, tender annuals and vegetable plants will be severely injured or killed if we hit freezing. About the only protection is covering these plants up and hope. But remember, covering plants protects them from frost, not temperature. I do advise watering plants late in the afternoon before a freeze is predicted for this time of the year. Water is a great insulator. Remember, the last frost date in the metro Birmingham area is April 15. Even if garden centers and big box stores have vegetable plants, like tomatoes and annuals like marigolds, please wait until around April 15 to plant them.


When can I plant seeds in ground? 28. March 2015

It depends on what you are planting. For vegetables, spinach, lettuce (mine is up), onions, and any of the greens like kale and turnips, plant now. I would recommend that you purchase plants of cabbage, broccoli, cauliflower, and Brussels sprouts, as they need to produce vegetables in the next couple of months. Plant these now. Everything in the vegetable category is fine to plant after the last average frost date in this area–April 15. For trees and shrubs, plant as soon as possible. For hardy perennials and annuals, plant now. For tender annuals and others, plant after April 15.


Where do you recommend buying herbs and vegtables you aren’t seeding yourself? Who has the best plants and variety, in your opinion? 28. March 2015

There are basically three growers I know of in this area, and the most widely distributed in this locale are Bonnie plants. Smaller growers who distribute in this area are Alabama Grown and Young’s. There may be others I do not know about. I buy from them all, but if you want some very unique things I suggest you go to the Birmingham Botanical Gardens plant sale which is April 10-12. Check their website for times and location.


Where can I find a white milk weed? 28. March 2015

I really do not have a good answer for you, but here are a couple of suggestions. Try the ‘Native Seed Network.’ I am sure they will have a number of milkweed types, and also check with the North Carolina Botanical Gardens. They have an excellent seed exchange program, and most years they have various types of milkweed seeds available, even if they are not listed (might have to call). Let us all know if you find them from another source.


I am considering planting milkweed to attract butterflies. Will it be hard to keep in check? 27. March 2015

That is a tough question, because there are many types of milkweeds. They scatter their seeds by the wind, so the common type–which is tall–can broadcast seeds far and wide. If you have a big native plant space, I think it would be okay. Most folks who have small spaces grow butterfly weed, and they do not have a problem scattering seeds. I so appreciate your efforts to plant things that attract monarchs.


I get excited every spring when the snowball viburnum forms it’s beautiful pom Pom flowers, starting with little green buds turning to white fluffy snowballs. from Darryl Moland 26. March 2015

You are so right. Mine is not as far along as yours, so I expect it to be showing itself around Easter. All of the Viburnums, which is the genus for Snowball, are under used in gardens around Birmingham. And thanks for tagging your viburnum picture with #BHMBlooms so everyone can see it on Instagram!


Hi John! If I have a bag of Miracle Grow Garden Soil from last year, are its nutrients still viable this year? 25. March 2015

Yes, use it as if it were a new bag. Most bagged soils can be open, kept, and used for many years.


I have some overgrown scraggly looking knockout roses in my backyard. When is the best time to trim and how far down should we trim to get pretty blooms? 25. March 2015

Normally, I would say prune roses before they leaf out (which is correct), but go ahead and prune your knock-out roses as soon as possible. They are the toughest rose I know, and they are hard to kill. I would lightly fertilize them after pruning with a low-nitrogen fertilizer like 5-10-10 (or a similar formulation). Roses bloom on new growth, so after you have pruned them to the height you want, then I would thin at least half of the tiny little branches.


What is the best granule insectiside to kill grub worms? 25. March 2015

The homeowner standard is an insecticide product containing triazicide, but there is a new product by Bayer Merit, which is getting rave reviews. I have not tried it, but I know Bayer is an excellent company. Just make sure, when you buy the granular product, that it contains one of these in the ingredient list.


John, I am so excited to find your blog! I have a couple questions for you. Is it too late to prune azaleas? And what’s the best method for VERY big overgrown ones? 24. March 2015

Actually it is too early to prune azaleas. I like to wait until they have finished blooming, and then shape with them hand pruning shears. As for the ones overgrown, you generally can severely prune them at the same time. I do recommend that you fertilize after pruning with a good fertilizer, like 12-6-6, or similar formulation.


John, What are the best blueberry plants for Trussville ?? 24. March 2015

There are a lot of ones that will do. I would pick from the list in the ‘Petals from the Past’ online catalogue. While you do not have to buy from them, Arlie Powell, who is one of the owners, is the best fruit grower I know in these parts. Blueberries are one of his specialties.


After I already placed my order and had my pine straw delivered last week, a friend of mine told me I should have waited until after the peak of the heavy visible pollen accumulation. He said that some of it will wash away with rain, but he prefers to wait so that he avoids pollen on fresh straw. I know this is probably only an aesthetic concern, but would you say it’s worthy of being a consideration in when straw is put down for the season? When do you predict we will have the most significant pollen accumulation this spring? 24. March 2015

First, pollen is with us most of the spring, but the heaviest time will be in the next few weeks. I would not worry about the pine straw being put down (because there will be more pollen all spring) unless your yard is full of trees, especially pine. If your straw has a yellow pollen build up, just spray it with a high-pressure garden hose, and that should handle cleaning the pine straw.


I see numerous posts/questions about the correct way to trim crepe myrtles, and I’ve done a bit of internet research to know how NOT to “commit crepe murder,” but have yet to come across a great website that has really good pictures of what TO DO vs what NOT to do. Like you mentioned, I see a lot of the trees around town that are hacked clean at a fixed height across 4-6″ diameter trunks… if you need a picture of what that grows into, I have a tree in my back yard that someone cut that way in the past. Very ugly knuckle with thin spindles coming out of it. I think the general public is hung up on the notion that the plant “flowers on new growth” so they feel the need to cut them annually. 24. March 2015

You make a good point. More is written about what NOT to do than the right way to handle Crepe myrtles. First, remember, they are trees, and if yours has been badly pruned in the past, I would recommend one of the following:
First remove all crossed or branches that rub against each other.
After that, stand back and look at the tree, and see how many original trunks or shoots the plant had. If is was a multi-stem plant, the goal is to keep that quality of the plant. If at the point where each branch has been pruned, you have multiple branches, I would remove at the break point all but one, three or so branches, and remove all others. This will encourage them to grow and create a nice multi-stem form over a period of years. If you can reach to old seed pod, snip it off, but it is not necessary. Now relax, and enjoy them recovering. They will make nice trees again in a few years. If your trees are in very bad shape and have been cut back to just big trunks, I would cut them to within a foot of the ground and start creating a new multi-stem tree. Once the plant breaks, and starts putting up new shoots, select three to five per trunk, and cut off all others. Allow these shoots to grow, and hopefully in a few years, they will produce a handsome specimen.


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13 thoughts on “Ask John

  1. Greetings John, My beautiful Peace lillies have an infestation of a scaly type of insect…aphids…I attempted to eradicate them by cleansing the stems and leaves with a damp paper towel and then followed up with a banana peel. As a deterrent, I would break off pieces of the peel and place around the top of the dirt. This seemed to work for a little while, but then I notice some of the leaves begin to grow limp and then turn yellow and I just cut them off. I would appreciate any suggestion and I really prefer the “Natural” remedy, but am open to whatever help you can offer. Thank you.

  2. thank you for replying re: fertilizing my various hydrangea types. I’m going to purchase the 15-0-15 you suggested and I plan to put some, dry, around the base of each plant. Some are very mature–the latest additions were planted in October, 2014. OK to treat all one time either now or very early summer? Thanks again.

  3. I transplanted some daffodils several years ago from my family home in Grove Hill, AL. The blooms do not seem as bright and yellow as they did in their previous environment. Is there a food they need to be more colorful and not so pale yellow? The foliage looks great; only the flowers are not as bright.

    • It might be several things, but usually the depth of color is pretty constant. Once they finish blooming, I would give them a bit of fertilizer. There are products especially for bulbs, but an all-purpose fertilizer like 15-0-15 (which is what most of us need to use in this area) can be sprinkled throughout the foliage. Also, if the bulbs you dug were in a sunny spot, and yours are in shade, that might affect the color somewhat. Other than that, I really do not have any ideas. Let’s hope next year the color will be brighter and clearer.

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