Drats, Gnats! Advice for Container Gardeners

by Andrea Laine, EMGV

In May I received a quick reminder of the downsides of overwatering. Temperatures soaring to 15 degrees above the seasonal average in my western North Carolina neighborhood caused me to give my container garden a second watering in less than a week since the last watering. Now, that might be called for in the middle of a hot summer given that plants growing in containers do not have access to a reservoir of groundwater. But it was still, technically, spring and, more importantly, my plants showed no signs of suffering. I watered in the morning as recommended and by afternoon I had mushrooms popping up in the plastic containers. I plucked them out; Two days later, there were even more! 

Photo by A. Laine, May 26, 2021.

On closer inspection I noticed something else – a number of teensy flies flitting all around the soil surface and sides of the containers. By overwatering, I created a perfect setting for fungus gnats.

Fungus gnats thrive in very moist, warm conditions and feed on fungi. Mushrooms are fungi. So weeding out the mushrooms was a good move; But not good enough. These gnats like to stay put. They live and rapidly breed in the top inch of soil and feed on organic matter and sometimes roots, too. A generation of fungus gnats (from female to female) can be produced in about 17 days depending upon temperature.1 In the right conditions, three to four generations can be produced in a year. As many as 272 eggs have been counted in a single female fly 2.

Fungus gnat on rim of plastic pot. Photo by A. Laine, May 26, 2021.

Another way I may have unwittingly invited the gnats to my garden is by neglecting two pots that contained perennials that did not successfully overwinter. The rotting roots of those plants could have been gnat food. I should have emptied those pots out weeks earlier. (I was hopeful that the plants might miraculously recover.)  

Fungus gnats are most often associated with houseplants where air circulation may not be ideal. My container garden was on a covered deck, so it mimics some of those conditions.

In the long run, the fix for the problem I had created was relatively easy: 1) I continued plucking mushrooms from the containers as they appeared. 2) I applied a neem oil drench to the soil every seven days for one month. Neem oil is a naturally occurring pesticide found in seeds from the neem tree3.  3) When temperatures returned to normal, I moved all the plants off the covered deck and into the yard where they would receive bright sunshine for most of the day and better air circulation. 4) I restrained myself from overwatering! 

Less is more: Water amply yet less frequently. Be sure your containers have holes in the bottom where excess water can drain. Be especially careful about watering plants potted in plastic containers. Plastic is not porous and will retain moisture. It will take longer for plants in plastic pots to dry out.   

Several plants were effected by my error, most were herbs and all have recovered. Only the borage (Borago officinalis) got noticeably worse before it got better. Its form is a little wacky now, but as of this writing (July 7) it is blooming beautifully and is visited by many bees.

Footnotes and Additional Resources

  1. http://ipm.ucanr.edu/PMG/PESTNOTES/pn7448.html
  2. http://pss.uvm.edu/ppp/pubs/el50.htm
  3. http://npic.orst.edu/factsheets/neemgen.html


Gnats on houseplants:

July: To Do in the Garden

By Gary Crispell, EMGV

It is July!  It is not hot.  You only think it is hot.  Hot is 114-in-Portland, Oregon-with-no-AC.   That, my friends, is HOT.

 June turned out quite well, I thought.  It would have been nice if Raleigh had shared a little more of their over abundant rain, but then, when has Raleigh ever shared anything good with Durham?  The gardens in our yard look pretty good right now except for the tomatoes that the voles got to… again.

They were not intimidated by the overlapping double layer of chicken wire in the bottom of the raised bed.  Next step is hardware cloth.  I’ll let you know about that next year.

The Accidental Cottage Garden is showing off presently.  There are black-eyed Susans (Rudbeckia fulgida), prairie cone flowers (R. hirta), coreopsis (Coreopsis lanceolata), liatris (Liatris spicata), Stokes aster (Stokesia leavis), balloon flower (Platycodon grandifloris), purple cone flower (Echinacea purpurea), Asiatic lily (Lilium x ‘Corsica’), gallardia (Gallardia pulchella) and a Hydrangea x ‘Limelight’.  The most amazing thing right now is the saucer magnolia (Magnolia soulangeana) that is reblooming.  Can’t say that I have ever seen that before.  Enough about our gardens.  Let’s put on some sunscreen and insect repellent and go out into yours.


Fertilize warm season grasses (Bermuda, St. Augustine or zoysia) now if you haven’t already done so.

Mow these grasses by removing no more than 1/3 of the growth.  Mow cool season grasses (fescue, bluegrass and perennial rye) at a height between 3” and 4”, no lower.


Last chance to fertilize landscape plants until 2022.

It is an excellent time to take soil samples and send them in to NCDA for FREE SOIL TESTS.  Boxes and instructions are available at the Extension office, 721 Foster St.  They are only free until November.


It is not too late to plant pumpkins, broccoli, beans, collards, Brussels sprouts, carrots and even tomatoes.

Get a jump on the Fall garden by planting seeds of cruciferous plants (cabbage, cauliflower, brussels sprouts) to be transplanted in mid-August.

Pot up or transplant overgrown house plants.


Trees that bleed a lot when cut (E.g. birch, maple, dogwood, elm) can be pruned this month.

Knock down those overgrown landscape plants and hedges.  August is too late.

Coniferous plants (seeds are produced in cones) can be lightly pruned now.

Keep garden mums pinched until the middle of the month for Fall blooms.

Blackberry and raspberry fruiting canes can be cut back to the ground after the last blackberry cobbler of the season.

To get a rebloom on perennials prune them lightly after the first bloom and before they set seeds.


Be on the lookout for these nefarious characters, bag worms (pick off the bags), leaf miners (take away their little headlamps), spider mites, aphid, lace bugs, and Japanese beetles. Spray sparingly and follow the instructions on the label. For many things, nothing more than insecticidal soap is needed.

Be aware of tomato blight and treat as necessary.

Continue the perpetual program for roses, fruit trees, and bunch grapes.

Pests of vegetables that are active this month include cucumber beetles (on cucumbers, ironically), flea beetles on tomatoes, beans and eggplants and aphids on anything they can get their sucky little mouth parts into.


If you are just bored you can build cold frames or greenhouses in preparation for the winter to come (‘cause it will come).  Personally, I am going to go out and sit under the gardenia (Gardenia jasminoides) in the backyard with a cold beverage and luxuriate in the heavenly odoriferousness of the blooms while listening to the indigenous wildlife communicate with each other.

So, let’s all get vaccinated so we can gather in the garden with friends.  Enjoy July, y’all.

*Resources and Further Reading

All About Soil Sampling and How to Get Supplies from Durham County Cooperative Extension

Organic Lawn Care Guide

Central North Carolina Planting Calendar for Annual Fruits, Vegetables, and Herbs

General Pruning Tips

Learn more about insects and how to control them from the North Carolina Extension Gardener Handbook

NC Extension Gardener Plant Toolbox (find your perfect plant or figure out what that unknown weed is!)

2021 Tomato Project

Last year’s tomato project, in which we compared the yields of grafted heirloom Pink Berkley Tie-Dyes to ungrafted Pink Berkeley Tie-Dyes, got us wondering if we could find hybrids that pleased our palates just as much as our favorite heirlooms.  Our curiosity was further piqued by the research going on at Klee Lab at the University of Florida, and the opportunity to participate in his trials as “citizen scientists.”

Since 1995, Dr. Klee has been trying to create the “perfect” tomato, one that: won’t bruise during shipping, resists many of the major diseases, is highly productive, and actually tastes good. According to Dr. Klee, “when we bite into a tomato, what our brains register as a “tomato” is actually a complex interaction between sugars, acids, and multiple volatile compounds.” He has reduced the essence of tomato to only 15 – 20 compounds that impact our perception of the fruit.

His first tomato, Garden Gem, was a cross between Maglia Rosa, rated by consumers as the best tasting tomato, and a “tasteless” workhorse, Fla. 8059. In variety trials among “a large consumer test panel run by the University of Florida Food Science and Human Nutrition department,” only two points separated Garden Gem from Maglia Rosa. In eighth place, Better Boy, the tomato most planted by home gardeners, ranked more than 12 points below Maglia Rosa.

The immediately identifiable shape of a Garden Gem.

As part of Dr. Klee’s citizen science project, we will compare performance, yields and taste among three of his hybrids: “R” Hybrid, “B” Hybrid, and an improved “Garden Gem”and against the hybrid classic, Better Boy. Expanding the project for ourselves we will also compare these four tomatoes with a variety of heirlooms which ranked high in our own taste tests, along with some new varieties we have learned about including three new offerings from Craig LeHoullier. We’re excited to see how the hybrids and heirlooms compare in terms of both performance and flavor.

Here’s what we’re growing:

Better Boy, Determinate Hybrid

Black Cherry, Indeterminate Heirloom

Black Krim, Intermediate Heirloom

Blazey F2, Craig Le Houlllier  (Honor Bright x Blazing Beauty)

Chef’s Choice Black, Indeterminate Beefsteak Hybrid

Cherokee Purple, Indeterminate Heirloom

Lemon Boy, Indeterminate Hybrid

Pamela’s Sundrop,  Craig Le Houllier (small yellow)

Pink Berkeley Tie Dye, Indeterminate Heirloom

R Hybrid, Klee Lab U of Florida,  Hybrid

Shin Chang Gong, Rootstock

Sun Sugar, Indeterminate Hybrid

Suzy F2, Craig Le Houllier (Sweet Sue x Peach Blow Sutton)

Once again, we’ll spend Tuesday, Thursday, and Sunday mornings at Briggs, grooming, picking, counting, and weighing our way to tomato Nirvana.  Except for those tomatoes in our end-of-season taste test, the produce will be donated.

Stay tuned for updates.

Learn With Us, July 2021

Durham Garden Forum: July 20, 7-8:30 PM via Zoom

Garden Transformations: From Blah to AhhMichelle Wallace Regional Agriculture and Natural Resource Extension Educator – Northwest Ohio, Central State University – Extension
A garden is always personal. Soil, weather, sun, pests, available plants, restrictions, all impact the choices and compromises you make, particularly when you are new to a region. But, the results will amaze you. This is about Michelle’s journey and the evolution of her landscape.
Via Zoom. For Registration Information, contact durhamgardenforum@gmail.com

The Bull City Gardener Learning Series has virtual and in-person classes. More information can be found HERE

Look for Gardening and Grub talks online on Wednesdays from 1-1:30 PM. Click HERE for the July 7 edition.

Guilford County Gardening Virtual Classes

Chatham County is also offering Virtual Classes

JC Raulston Arboretum offers additional online events.

Virtual and in-person classes are being held at the NC Botanical Garden

Triangle Gardener Magazine compiles a list of courses from many of the above sources and others.

Safely Gardening With Children

By Jean Findlay, EMGV

It is so rewarding to see children get excited about gardening. They get outdoors with fresh air and exercise, away from screens, learn about plants and soil, and maybe improve their diet when they can eat and prepare what they have grown. And gardening can be done anywhere, and from a young age. This little one started to help garden at age two on a rooftop in Kuala Lumpur, Malaysia!

While you are planning quiet summer afternoons in the back yard, your children may be plotting some mischief! A little preparation will help prevent a trip to the emergency room on an otherwise peaceful afternoon. So here are a few suggestions to keep everyone safe and happy.

Do a tour of your back yard to check for hidden dangers. Check for poisonous plants and remove them if possible. A plant ID app can identify the name, and the printable publications below (references 5 and 6) list plants poisonous to humans and animals respectively.

Have a first aid kit handy, as well as the phone number for poison control:


Make sure chemicals and petroleum products are safely stored. Pesticides and other chemicals can be absorbed through the skin, so they should never be handled by children. Ingestion of petroleum products can cause severe pneumonia. Make sure you watch chemicals while you are using them, until safely stored again.

Keep young children off a newly treated lawn for 48 hours.

If there are water features, rain barrels, paddling pools or drainage ditches, be sure there will be adequate supervision of toddlers. Toddlers have been known to do headstands in the toilet bowl, and if exploring a water feature combines with a fall, the result can be disastrous. Keep hoses coiled to prevent tripping.

Time for the pre-gardening lecture!

Before heading out to the garden to plant those prized heirlooms you’ve grown from seed, go over the rules. Garden tools are not toys or weapons, boys and girls! They should always be put on the ground with sharp points down. If tools are not scaled to size, make sure each little gardener is aware that there is a long handle behind them that can hit another child if too close.

They should wear sturdy shoes, and when appropriate, hat, sunscreen, eye protection, and insect repellant. Have plenty of water available to drink in hot weather.

Instruct them to only eat fruit or vegetables under adult supervision. Not all blue berries are blueberries; Poke berries for instance, are very toxic to young children. And Swiss chard looks quite like rhubarb whose leaves contain too high levels of oxalic acid for children to tolerate. For the vegetables and fruits you do harvest together, it is a great time to maybe let them taste some new and healthy food, and learn how to cook them with you.

Plants, pests, and power tools:

Some general recommendations from AAP and CDC:

  • Sunscreen: SPF 15 or more, apply 30 minutes before exposure and every 2 hours of exposure, and after swimming.
  • Insect repellent: 2 months and older : 10% DEET for up to 2 Hours exposure, 30% for up to 5 hours. Wash it off when return indoors.
  • Light colored clothing, avoid perfumed products, and cover up as much as practical.
  • Check for ticks each day. If found, remove carefully and record the date.
  • Combination sunscreen-DEET products risk extra exposure to DEET since it should be applied more frequently.
  • Power tools: only over 14 years of age, and if able to handle the equipment.
  • Mowers: This is my pet peeve! No matter how cute they look, NEVER let a child ride on a tractor or ride-on mower. They can fall off, sustain a head injury, be run over, or lose part of an arm or leg. It happens more often than people realize.
  • Age 14 + to operate a walk-behind mower, and 16+ for ride on mower.
  • Be sure to turn off the mower before removing grass from the blades (yes, I know someone who didn’t and got more than his nails trimmed)

Additional Information and References:

  1. Gardening Safety for Kids, Part 1: Getting Ready for the Garden (MSU Extension)
  2. Gardening Safety for Kids, Part 2: Using Tools and Preventing Injury (MSU Extension)
  3. Water Safety and Young Children (American Academy of Pediatrics)
  4. Choosing an Insect Repellant for Your Child (American Academy of Pediatrics)
  5. Poisonous Plant Resources (NC State Extension)
  6. Plants Poisonous to Livestock and Pets in North Carolina (NC State Extension)
  7. Guide to Accidental Plant Poisoning (Carolinas Poison Center)
  8. Sun Safety (CDC)