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


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.


I’m building an 18″ raised vegetable garden. My existing topsoil is good but a little heavy in clay. Lots of organics. I’ve got access to coarse golf course green sand for free. My thought was to mix 40% sand with the topsoil. With this limited info John, what do you recommend? 22. March 2015

If you think your soil is really heavy, 40% probably would be fine. But remember, if it is too sandy, watering in the summer is going to be almost daily during dry periods. When I read your note, my first thought was 20% thoroughly mixed, especially if you can add lots of organic matter. One thing is important: Many times with new raised beds, while their first year of production may be okay or good, the second year and forward should improve. This is because the decomposition of the added organic matter and the turning of the soil will help the soils texture and porosity.


Would you please throw in a couple of tips for gardening at the beach? I would imagine some of your readers have second homes along the Gulf. 20. March 2015

First, it really depends where you are located, but for the sake of this discussion I am going to assume the Gulf Coast. The only gardening area in that part of the world that I am familiar with is around the Destin/Seaside area. First and foremost, for the last two years this area has had tough freezes. When I was in the area last month, most evergreens had suffered some cold damage, but I expect most of these plants will recover. Be patient, and realize all the damaged leaves will drop off, and new ones will appear. As the new foliage breaks start growing, fertilize lightly with a product like 6-12-12. Or use something that is low in nitrogen (the first number), compared to the other numbers. Remember, with sandy soils, you will need to keep things that are not native watered during dry periods.  Also, adding organic is always a good idea when planting anything.


I have gardenia bushes 6 feet tall. How aggressively can I cut them? 17. March 2015

In fact, we pruned one about this time last year at the Botanical Gardens, reduced its size about 50%, and it did fine. Remember, when you prune, go deep into the plant and remove the limbs with good pruning tools (see post on pruning tools), and make clean cuts. Once the new growth starts, I would do two things: Mix one heaping tablespoon of epsom salt in a gallon of water (make sure it dissolves), and pour it around the base of the plant, and fertilize it lightly with a low-nitrogen fertilizer (first number on the bag needs to be low).


is it too late to trim crepe myrtles? 17. March 2015

Not really, but the way you see them pruned around town is not correct. Remember, they are trees and should be treated like you would a dogwood or flowering cherry. Only remove crossed branches and those branches that destroy their shape. Hacking them off at some height is a very bad way to prune them, and does not produce a beautiful plant (or should I say tree). There are excellent selections on the market that will grow to almost any size you desire, from about 3 feet tall and up.


I have a Granny Smith Apple tree that I planted a few years back. Every year I battle black spot with it, as my neighbor’s roses are covered in it. I’m tired of fighting this losing battle. Should I just transplant the tree to another location where roses aren’t around? If so, when can I move it? Could it survive it a giant pot? 17. March 2015

First, moving is advisable if your neighbors are not going to take care of their roses. And yes, apples will grow and produce fruit in pots, assuming they are large enough (would say a minimum of 35 gallons). The best time to transplant it is in winter, so if you move it now, the risk of it not making it goes up dramatically. Do not even try to transplant it if the buds are already swollen.


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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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