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


Hi john, I have some new england asters that I bought at the BBG sale last spring. They get really tall, and I’d like to encourage them to be more bushy. I’ve read that you can ‘pinch’ back the tops, but is it too late to do that considering how tall they are now? 2. May 2020

They are considered a late summer to early fall bloomer, so I would feel comfortable cutting them back to mid-summer. This will still give them time to produce flower clusters for fall flowering.


Among the treatments listed to get rid of sawflies which one do you recommend? 26. April 2020

A blast of soapy water that knock the off the leaves is a temporary fix. Most insecticides say they control them but for long term results dust with Diatomaceous Earth.


Hi John, I am confused about fertilizers for acid loving plants; products such as ‘Holly-Tone’ and ‘Ferti-lome Azalea, Camellia, Rhododendron 9-15-13?’ The Holly-Tone has numbers of 4-3-3, yet the Ferti-lome has a higher middle number? Why are they different and which one would you suggest for azaleas, gardenias, camellias, etc? Thanks!’ 6. April 2020

I think either is ok but the high middle number is phosphorus and our soil are typically high in phosphorus. I would recommend that you use 15-0-15. It will save you a lot of money and will probably get as good or better results.


I am located in Lee County and looking to direct sow seeds into my vegetable garden. One problem – we are expecting 5-6.5 inches of rain over the next two weeks. While there are dry days in there that I could potentially sow, I am concerned about too much moisture rotting my seeds. How much rain is too much rain for newly sown seeds? If I wait until after this rainy spell, I am concerned that it might be getting too late in the season for certain vegetables. I could start the seeds indoors and transplant later but I would rather avoid transplanting if I can. 6. April 2020

With that much rain I would not seed the veggie garden until the heavy rains are over. I often time start in pots and then transplant to the garden. I am afraid with that much rain the seed will wash everywhere.


Would you happen to know a good place in Alabama to get a young Meyer lemon tree? 1. April 2020

Meyers Garden Center, Hanna’s Garden Shop, and Warren Family Garden Center should be good sources. But, I would call first to make sure they have some that have not over wintered in their greenhouses


Looking for Elsie Lee azalea. Would you know good online supplier? 5. March 2020

Wilson Brothers has good credentials. Have not ordered from them.


I have a cedar shrub planted in an Urn .. it has been there for about 5 years, Ive replaced the soil several times and it is growing and healthy… My question is , can I prune it to make it more shapely, or would that not work with this type shrub? Its about 2-3 feet tall and is losing its pyramid shape. 5. March 2020

It is perfectly fine to shape them and I would do it asap.


Hi John, I have used Hi-Yield Weed and Grass Stopper with Dimension Herbicide with great success in my lawn and am going to try it this year in my shrubbery beds (which are mulched with pine straw.) None of the shrubs I have are listed as sensitive to it. My question is, “Can I also use this in my perennial flower bed? Will it prevent any self-seeding plants from germinating or just the seeds/grasses listed on the product? Thanks 28. February 2020

After reviewing the product label, I would think you would risk herbicide damage on perennials. Daylilies however was on the approved applications list. If you decide to risk it try a small area and see if it damages your plants.


I would like to plant dahlias. Dahlia sites say plant them two weeks after last frost. How do I know when that is? 27. February 2020

The average last frost date in our area is April 15


I have tried everything to rid azaleas of white flies. It works for a short time but they come right back. How do I rid my plants of these? 1. February 2020

The best product on the market now is Bayer Duel Action Azalea and Camellia product. Caution- wait to apply after flowering as the systemic in the product can be harmful to bees.


Please recommend fragrant trees and/or shrubs to plant. 29. January 2020

First, there are books written on this subject. The library at the Birmingham Botanical Gardens has excellent resources on the subject. My favorite fragrant shrubs include gardenia, wintersweet, anise, banana shrub, and spicebush As for trees Southern Magnolia is tops followed by sweetbay magnolia, and lilac chastetree.


I have a semi-shady and very steep slope in my backyard that’s about 8 feet high. I would like a ground cover that could make the space green and help with erosion but not sure what to choose. 24. January 2020

On a very steep slop in shade many ground covers will work but getting them established without causing the bank to erode can be a big problem. Probably the most vigorous on for this type of situation is English ivy and you can by it as sprigs from many nurseries. Others that work would be monkey grass and liriope. They can also be purchased in 4-inch pots. A little used ground cover for this type slope is the small leafed periwinkle (Vinca minor) as it roots when the stems touch the ground like ivy but is hard to find. Probably if you use Vinca you will have to have a friend to give you some. Be sure you plant each pots well and if the soil on your slope is poor amend the soil, mulch with pine straw when planted to prevent erosion. Watering the first year of establishment is a must.


Which weed killer is the safest to use on centipede and St. Augustine Grass… 2-4D or Atrazine… 21. January 2020

Checking with herbicide specialist. Will get back to you- john

Update- the expert says atrazine


Hi John, I have some hardy mums (don’t know the cultivar) that someone gave my grandmother in 1988; she had them in her yard and all the cousins have them, and BOY, are they hardy. I have been told that you can pinch the tops back to keep them bushier but you need to stop before end of June. My question: How late can I pinch them back without messing up the fall blooms? 17. January 2020

From bud set to bloom is 6-8 weeks. So the later you pinch them back the later they bloom. Most years we do not have frost before early November, so it just depends when you want them to bloom as to when you do your last pinch. Plan on 10-12 weeks after pinching before blooms show color.


Is 2-4D Weed killer safe to use on Centipede, St. Augustine yard this time of year… Hoping to kill clover before spring! 6. January 2020

While 2,4,D will not kill Centipede and St Augustine it may injure it. So it is up to you,but if dormant it will have less chance of injury.


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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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