June: To Do in the Garden

by Gary Crispell EMGV

The calendar claims it is June. The weather, well, the weather is about as seasonally correct as the stock market is an accurate indicator of the economy—worthless mostly. Presumably we are through covering tender vegetation until October—presumably.

The “Accidental Cottage Garden” in my front yard is still delighting and surprising every day. Now that the red clover (Trifolium praetense) has finished, the poppies (Papaver orientale) are front and center in an amazing variety of colors. The cornflowers (Centaurea montana) are fantastic. I had no idea they came in so many colors, deep red, purple, magenta, hot pink and, of course, cornflower blue. There are still several plants I have not identified. Can’t get out there with the book between rain showers. Cosmos (Cosmos bipinnatus) will be the next major player.  What’s exciting in your garden?

Cornflowers (Centaurea montana) come in many colors! Photo by G. Crispell.

Lawn Care

If you have heretofore procrastinated on this item it is TIME to fertilize warm season grasses (i.e. Bermuda, Zoysia, St. Augustine). It is also the best (and really only) time to fertilize Centipede. The general recommendation is for one-half pound 15-0-14 or equivalent per 1000 square feet. Should you desire to be truly accurate-GET a FREE SOIL TEST. Kits are available for contact-free pickup at the Cooperative Extension office, 721 Foster Street, Durham.

It would be difficult to core aerate our clayey soils too much, so a day or two after a rain (like any day this spring) or a good irrigation would be an ideal time do just that.

When mowing warm season grasses a good rule-of-thumb is to remove one-third of the new growth per mowing.

If you have been drooling over your neighbor’s Zoysia lawn, June is a good time to start your own with sod or plugs.


After getting your FREE SOIL TEST in order to avoid overfertilizing, now is the time to feed your dogwoods following the recommendations.

Vegetable gardens would like a side dressing of fertilizer about now to maximize production.


Again, for the procrastinators out there, if you want a crop this year better get these plants (too late for seeds) in the ground ASAP: tomatoes*, peppers, black-eyed peas, lima beans, green and wax beans, pumpkins, sweet potatoes.

Start (from seed) Brussel sprouts & collards to set out in mid-July.


Coniferous evergreens like pines, cedars, junipers, arborvitaes, etc. may be pruned now. (Coniferous evergreens produce seeds in cones.)

Hedges can be pruned now but be advised do not remove more than a third of the total plant top. (The green part.)

Keep pinching your garden mums until mid-July.

Hydrangea macrophylla (the ones with the BIG leaves) can be pruned when the flowers fade.

Azaleas may be pruned until July 4. (An “old wives tale” that works.)

Dieback in ericaceous plants (acid-loving) such as azalea, rhododendron, Pieris, etc. can be pruned out now.  Remember to cut below the damage and to sterilize the pruner with 10% bleach between cuts.

Pest Control & Herbicides

Patrol your shrubs for the following likely suspects: lace bugs, leaf miners, spider mites, aphids and bag worms. Use appropriate measures to curtail their destructive tendencies. If the bag worms have already bagged themselves you will have to hand pick them and destroy them in any manner you see fittin’.

June is also the beginning of the Asian invasion better known as Japanese beetles.  There is a myriad of treatment options out there.

Tomato* early blight could be rampant this year what with all the warm dampness. Watch for dark spots on the leaves and treat with an appropriate fungicide. There are some good organics out there.

June is a good month to eradicate poison ivy, kudzu and honeysuckle. Get ‘em with an appropriate herbicide while they are rapidly growing.

As with shrubs it is time to be on guard in the garden. Several (many?) insects are looking for gourmet gardens to satisfy their gastronomic inclinations. Look for a variety of worms on cruciferous veggies (cabbage, broccoli, cauliflower), cucumber beetles on cucumbers (ironically), squash borers on other cucurbits–squash and melons, flea beetles on green beans, tomatoes and eggplant, and aphids on anything green.

Continue with regular pest management programs on bunch grapes, fruit trees and roses.

Use pesticides wisely, sparingly and only when necessary. Always read the label and follow directions.

Other Fun Garden Stuff to Keep You Outside

Water lawns as necessary but try to do it early in the day to avoid evaporative loss.  Watering lawns in the evening promotes disease. Lawns and gardens need about one inch of water per week either from natural sources or irrigation. 

Strawberry beds can be renovated now.

It is also a marvelous time to sit on the deck or patio with a glass of your favorite cold beverage and enjoy your garden. And if your deck is spacious enough for six-foot distancing you can invite friends, but no more than 25. Use triangular spacing.  It’s more efficient. Wear your masks and wash your hands, again.  Stay safe, y’all.

*Speaking of tomatoes, visit our Tomato Grafting Project page for an update about this special project! Learn more

Asian Giant Hornet Not Detected Yet in NC

With the emergence of the Asian Giant Hornet in Washington State, the NC Department of Agriculture and Consumer Services is urging North Carolina residents to be vigilant and report potential sightings of the pest.

Asian Giant Hornets are the world’s largest species of hornet, measuring about an inch-and-a-half to two inches long. They have an orange-yellow head and prominent eyes, with black and yellow stripes on their abdomens. The hornet is not known to occur in North Carolina, and our state’s apiary staff have been actively monitoring for the pest with no detections to date.

“The Asian Giant Hornet is a threat to honeybees and can rapidly destroy beehives, but it generally does not attack people or pets,” said Agriculture Commissioner Steve Troxler. “There are many wasp and hornet look-alikes that are beneficial insects, so residents are asked to exercise caution before deciding to kill any large hornets.”

Cicada killers and European hornets do occur in North Carolina and can be confused with the Asian Giant Hornet. Residents can visit https://agr.wa.gov/departments/insects-pests-and-weeds/insects/hornets/size-comparisons to see a photo of the Asian Giant Hornet along with common look-alikes.

If you think you have seen an Asian Giant Hornet, take a photo and submit it to the North Carolina State University’s Plant Disease and Insect Clinic. Instructions on digital submission can be found at https://projects.ncsu.edu/cals/plantpath/extension/clinic/submit-sample.html  under Option 3.

For more information about the Asian Giant Hornet, visit the NCSU Cooperative Extension or read our pest alert at https:///www.ncagr.gov/plantindustry/plant/entomology/documents/AsianGiantHornetPestWatch.pdf.

Busting Myths

by Andrea Laine EMGV

One of the things we master gardener bloggers take pride in doing is busting gardening myths. Our approach to accomplishing that is by presenting readers with a common problem or challenge, describing our firsthand experiences, and then sharing recommended solutions from the agricultural research-scientists associated with NC State Extension Services and nearby states that share our climate, soil and other growing conditions.

The approach we generally avoid is saying, “Hey, so-and-so said do this and here’s why you should not follow their advice!” I’m about to break with that tradition because of a gardening “how-to” piece I just read in an international newspaper with a large circulation.

The piece illustrated how to carve a garden out of your lawn using wet layers of newspaper, several sheets thick, and mulch on top. So far, so good. Where it goes astray is instructing you to plant immediately afterward by cutting holes through the paper and through the sod. Why bother with the paper if you’re going to need to cut the sod anyway? And, guess what, sod is a living being, too. While it is still trying to live under that newspaper it is competing with your annuals or vegetables for water and nutrients. For best results, leave that newspaper and mulch in place, untouched (except for watering) for six months, so whatever was underneath (sod or weeds) ceases to grow and is well on its way to breaking down into compost. By the way, cardboard works as well as newspapers*.

The newspaper and writer had good intentions. We are living in unusual times — people across the US and around the world — are staying home to minimize the spread of Covid-19. It is springtime and people are gardening; even people who rarely if ever gardened before. That’s great!!! Gardening has many benefits to our physical and mental well-being, and to the environment.

Anything worth doing is worth doing right. So, whether your motivation to garden is putting food on your table, enjoying pretty flowers in your landscape, or sprucing up the yard or lawn to help pass time while you are staying home, master gardeners can teach you how to do it right. Let the over-simplified instructions and pretty pictures in mainstream newspapers, magazines and social media inspire you. When you are ready to take action, seek out sources devoted to the area of gardening that you are most enthusiastic about. NC State Extension’s archive of horticulture publications and fact sheets is a great place to begin. (After following this blog, of course!) And you can always send us a question at durhammastergardener@gmail.com.

Further Reading

*Consider planting a container garden while waiting for your newspaper to breakdown.

Horticulture publications and fact sheets from NC State Extension

Better ways to carve a garden out of your lawn or over a bed of weeds

Extension’s Durham County Center news and information

Iris Gardens

By EMGVs Jackie MacLeod and Cy Gurney

Cy Gurney and I became friends and Extension master gardener  volunteers at the same time, so perhaps it’s no surprised that we share a love for growing irises. Our two Durham gardens present different growing conditions. My garden is a sunny downtown location. Cy’s garden, in the northern part of the county, is shaded by mature canopy trees. Yet we both are able to enjoy growing iris, an ornamental plant that commands attention at spring time with their regal stature, big blasts of color and, as with some varieties, that gentle scent of a freshly opened bottle of cream soda.

The name iris comes from the Greek word for rainbow–a reference to the vast amount of colors that irises display. They are easy to grow in zones 3 to 8 in the East. They prefer a sunny site and a light, loamy soil with pH of 6 to 7. They don’t like their rhizomes wet, so amend your clay soil with organic matter to improve drainage. Also, bury the rhizome firmly in the soil but near the surface; if planted too deeply, an iris will not bloom. Plant them in July, August or September and they will reward you the following year. 

Iris in Jackie’s Sunny Garden

An iris flower has three upright petals called “standards” and three hanging petals called “falls.”

Some irises have fuzzy  growth at the beginning (central side) of each fall. That is called a beard and those irises are Bearded Iris or Iris Germanica. The beard can be in contrasting colors to the petal (fall) below and is assumed to help attract pollinators.

A bearded iris. Photo by Jackie MacLeod.

Below is a picture of a Bearded Iris very similar to ‘Madame Henry Cayeaux.’ The light pink colored petals are the standards, the deep purple falls have a lighter color variegation towards the center and, laying on top of it, you can see the fuzzy yellow beard.

Photo by Jackie MacLeod

Here is another Bearded Iris. You can see the yellow beard laying on the striated yellow-gold and purple fall. If you compare the petals to the bearded iris in the picture above, you will see that these petals are ruffled. I believe this iris is called ’Nibelungen.’

Iris ‘Nibelungen.’ Photo by Jackie MacLeod.

Here is a variegated purple and white Bearded Iris. The flower shape and beard are much harder to discern in this variety ‘Batik,’ (see photos below) which is German for tie-dye. It’s quite the show-stopper!

-Jackie MacLeod

Iris in Cy’s Shadier Garden

Irises have long been a favorite for many gardeners, yet not all gardens have the full sun needed for the large and beautiful bearded irises. If your tree canopy is tall and not dense, in the spring you can try these types of  irises in your part-shade garden. These were in full bloom in April in my shady garden in northern Durham.

Iris japonica ‘Eco Easter’ is also known as Fringed Iris and Butterfly Flower. This is an easy to grow plant. It spreads 12 to 15 inches and grows in dense clumps of broad fans of green strap shaped leaves. It is an evergreen herbaceous perennial. It has two-inch  lavender-blue flowers that have a yellow base and with darker purple markings on the lower petals (the falls) with the inner lavender-blue petals (the standards) that are narrow with fringed tips. The buds flower on multiple stems, which bloom reliably and in secession during early to mid-spring. It thrives in  part-shade to full-shade and is deer resistant. It spreads by long slender, creeping rhizomes, making this an easy plant to share.

Iris Japonica ‘Eco Easter’. Photo by Cy Gurney.

Iris hollandica ‘Dutch Iris’ (pictured below) grows from a teardrop shaped bulb. The flower colors are pale blue, lemon-yellow and deep purple, bronze, rose and gold. These are popular because they are long-lasting and look great in a flower vase. They have tall 18- to 24-inch sturdy stems which look nice in the back of a spring garden. The bulbs were planted in the fall among daffodils and tulips. They can rebloom a second year, but most gardeners treat them as annuals and replant new bulbs each year. They perform best in sun but they will also grow in part-shade.

Iris hollandica ‘Dutch Iris’. Photo by Cy Gurney.

Iris tectorum ‘Roof Iris’ is a herbaceous perennial. This is a 15-inch tall species of the crested iris group with large, six -inch across, beardless, bright lilac-purple flowers which are crested white. The leaves are in fans of narrow, lance-shaped leaves that are supple and arc in a lovely display. The rhizomes should be spaced 16 inches apart as this plant can spread vigorously, so plant with a plan in mind. It is deer resistant and does not require a great deal of water. It does well in sun and part-shade gardens. The common name is derived from the historical use on thatched roofs in its native China and Japan.

Iris tectorum ‘Roof Iris’. Photo by Cy Gurney.

-Cy Gurney

Sources & Further Reading

Planting and growing irises

NC Extension Plant Toolbox

Missouri Botanical Garden Plant Finder