Learn With Us, week of August 4

Cool Season Vegetables
Saturday, August 10⋅10:00 – 11:00a
m
Durham Garden Center
4536 Hillsborough Rd, Durham, NC 27705
Growing COOL SEASON VEGETABLES in the Triangle region presents unique challenges and rewards. Topics will include species and varieties that can be successfully raised when the tomatoes and peppers have finally finished. Planning early for late-season planting as well as the different challenges of Fall temperature, moisture and soil depletion will all be discussed. Also of interest will be techniques and materials that will abet over-wintering of certain crops as well as preparing beds in the Fall for Spring planting next season.

Free, registration required. Sign up at the store, online or by phone
Include the seminar title and full name(s) of persons attending

August: To Do in the Garden

by Gary Crispell, EMGV

Alrighty then! We survived July, just barely. Thank you, Mother Nature, for the break at the end of the month. So, how does your garden look?  And the water bill? (Ouch!) Well, July is behind us now and August is upon us with her bounty of veggies and plethora of blooming plants. Let us hope the rain gods will be less capricious and the heat stays somewhere else. Whether or not those things come about there are things to do in the garden and don’t forget to be hurricane prepared. (You know, the ones that come in off the ocean – not the ones that reside at PNC Arena.)

Lawn Care

Check the lawn for grubs. If you find some, treat with an appropriate insecticide. If you do find any, be grateful and put the sprayer away.

Late in the month prepare any areas that need to be seeded with cool season grass (tall fescue, bluegrass).

Fertilizing

Give your strawberries a shot of nitrogen fertilizer.

DO NOT fertilize trees or shrubbery until December.

Planting

Sow pansy seeds this month in flats to transplant to the landscape in September.

Perennials, hollyhock, delphinium and Stokes’ aster can be sown now for healthy plants in the spring.

Repot more house plants.

Plant a fall garden with beets, Chinese cabbage, cucumbers, kale, kohlrabi, lettuce, mustard, radish, rutabaga, squash and turnips.

Pruning

Nada. Nope. Don’t! No pruning of trees or shrubs until November.

In case of hurricane damage, disregard the above admonition.

Spraying

Same stuff as last month. Look for spider mites on coniferous evergreens (juniper, arborvitae, etc.) and lace bugs on azaleas and pyracantha.

Continue rose spray program and weekly spraying of fruit trees and bunch grapes.

Watch for worms on cruciferous vegetables (broccoli, cabbage, cauliflower) and borers on squash.  Spray only if necessary. Follow the label instructions.

Propagation

You may still take cuttings of shrubs.

More fun things to do if you just can’t get enough of the August heat

Make sure your LANDSCAPE PLAN is up to date especially if you plan to modify the landscape this fall.

Keep running up the water bill when the August thunderstorms skip your house.

Build a compost bin.

Dig Irish potatoes.

Stay cool and hydrated. September and October will soon be at hand.

A New Factor in “Right Plant, Right Place” — low-E Window Coatings

By Wendy Diaz, EMGV

A couple of weeks ago, during the peak of our latest heat wave here in the Piedmont of North Carolina, friends asked me about brown stems on their new foundation shrubs Cryptomeria japonica Dragon Prince ™ which they purchased at a local nursery and planted this spring (Photo).  These compact attractive shrubs were not established, but they were watered regularly in order to sustain them through their first year in this location with exposure to afternoon-sun in a west-facing front flowerbed.

Photo 1 Brown stems on new foundation shrubs Cryptomeria japonica Dragon Prince ™ Photo by Wendy Diaz July 13, 2019

We ruled out lack of water as the culprit and suspected that the location of the shrubs in front of their new low-emissivity reflective windows could possibly be the reason for the browning of the shrubs foliage (Photo 2).  I asked my friend to measure the temperature at the shrubs location and in the early evening it was over 140 degrees Fahrenheit.  

Photo 2 The location of the shrubs in front of their new low-emissivity reflective windows Photo by Wendy Diaz on July 13, 2019

On closer examination it was observed that the bottom part of the brown stem tip, closer to the trunk of the plant and more sheltered from the surface, still appeared to be green and healthy (Photo 3). A rigorous scientific study was not conducted as part of this article but circumstantial evidence of a thermometer reading over 140 degree Fahrenheit certainly leads one to believe that the intense heat caused by the suns rays reflecting off low-E windows could be the cause of the plant’s distress.

Bottom part of the brown stem tip, closer to the trunk was green and healthy. Photo by Wendy Diaz on July 13, 2019

Could the shrubs brown crowns be the unintended consequence of making changes to the energy efficiency of our homes by causing another problem to the outside home environment during the more frequent intense heat waves? Low-emissivity (low-E) coatings are transparent and improve the efficiency of the glass by reflecting heat out but still letting in light. The coating is applied to the outside glass to reflect the sun’s heat out. It has been reported that heat generated from double paned low-E windows reflecting sunlight was measured in excess of 200 degrees Fahrenheit.

A possible choice to replace the front foundation shrubs may not be an evergreen non-native but perhaps a native Yucca filamentosa with some ground cover of Indian blanket flower(Gaillardia pulchella). The Cryptomeria japonica shrubs were dug up and re-potted and moved away from the low-E windows to prevent further damage awaiting replanting in the fall. Evidently some do not like it hot!

Learn With Us, week of July 27

Mosses – Fifth Season Gardening Co.
Saturday, July 27
10:00 – 11:00am
Fifth Season Gardening Co
106 S Greensboro St D, Carrboro, NC 27510
Our presenters will discuss enough natural history of mosses to make establishing and caring for a moss garden understandable. The session then will cover how to encourage moss already on the property, how to plant a new moss area, and how to keep things going. There will also be moss samples for pure enjoyment.

Cool Season Vegetables
Saturday, August 3 10:00 – 11:00am

For Garden’s Sake
9197 NC-751, Durham, NC 27713
Growing COOL SEASON VEGETABLES in the Triangle region presents unique challenges and rewards. Topics will include species and varieties that can be successfully raised when the tomatoes and peppers have finally finished. Planning early for late-season planting as well as the different challenges of Fall temperature, moisture and soil depletion will all be discussed. Also of interest will be techniques and materials that will abet over-wintering of certain crops as well as preparing beds in the Fall for Spring planting next season.

Free/Registration required
To register, email ann@fgsnursery.com or call 919-484-9759

Ten Plants That Can Take the Heat

by Andrea Laine, EMGV

Come July, I am unlikely to be outdoors — much less gardening—unless watering or weeding is absolutely required. I dislike the heat of a North Carolina Piedmont summer. Luckily for my garden and the birds and insects who visit it, there are perennials and annuals that do just fine despite the heat and even when rain is not plentiful.  

I’ve been noticing those plants more lately as it has been almost two weeks since a measurable amount of rain has fallen on my garden. And, we’ve had some very hot days, with heat indexes of 100 or more. I watered six days ago and again this morning (July 20).

Plants begin suffering physiological damage at 86 degrees and above1. Keeping up with watering is important, especially for the newer additions to the garden or those recently transplanted. An established tree, shrub or plant will fare better due to a stronger, more settled root system.  

Here are 10 plants that tolerate sunny, hot, and dry conditions reasonably well:

Perennials

Blackberry Lily or Leopard Flower (Belamcanda) This is my first experience with this semi-hardy summer bulb. It prefers morning sun, but this plant is doing very well in afternoon sun in well-drained soil. The dainty flowers began blooming in July atop stalks 30 to 36 inches high. Blackberry refers to the black seeds that follow flowering. Store corms in dry sand at 35-41 degrees.


Catmint (Nepeta ‘Walker’s Low’) This is another plant I had never grown before this year and so far I am very pleased. Lavender spikes of flowers (10 inches high) appear late spring to mid-summer and flowers are always crowded with bees, moths and butterflies. It is deer resistant. Photo credit: Debbie Roos


Lantana (Lantana Camara) The ‘Miss Huff’ cultivar is a generally reliable perennial in the Piedmont region of NC. Treat all other cultivars as annuals here. Miss Huff is a woody evergreen shrub that will grow 4’ high and wide in full sun. It blooms from late spring to fall and flowers are a mix of orange, yellow and pink. Cut it down to four to six inches in the spring before new growth begins.


Garden Sage (Salvia Officinalis) This plant is the star of my herb garden – good-looking, evergreen and productive all year. It is planted in well-drained soil and receives four to six hours of sun; that’s about as ‘full’ as my heavily wooded property allows, but obviously it has been good enough for this plant.  


Purple coneflower (Echinacea purpurea)  Being native to the southeast United States, it’s not a great surprise that the purple coneflower tolerates heat and drought. But it also tolerates humidity and poor soil and can grow in full sun or part shade. Pinkish-purple flowers appear from May to October. It is deer resistant, too. Photo credit: https://plants.ces.ncsu.edu/plants/echinacea-purpurea/

Annuals

Summer snapdragon (Angelonia angustifolia)  For years now I have relied on this annual to add color and grace to my front walkway. I choose white and purple flowering cultivars but there are pink and variegated ones, too.  It grows at a medium rate and flowers from June through September. I bet it would do well in a container. Actually, most plants that tolerate drought probably would.


Begonia x ‘Dragonwing’ This has long been my favorite begonia because it fills out so nicely. I don’t readily think of begonias as being heat and drought tolerant, but I’ve included this one because of my firsthand experience with it under exactly those conditions. I love its drooping clusters of flowers. I usually plant this in a container on my deck which receives morning sun. This year I put it in the ground outside my front door,  a western exposure that also receives a good bit of shade. As you can see, it is doing well.


Evolvulus  glomeratus ‘Blue daze’ It was serendipity when I spotted this plant in a nursery in Mebane last summer. I was through with my planting for the season (or so I told myself) but just couldn’t resist its charms. I do like plants with blue flowers. I brought it home without knowing anything about it. I put it in the ground in full sun among some perennial grasses and it proceeded to take over! I eventually learned that it is a ground cover in the morning-glory family. It’s flowers close at dusk or on cloudy days. If planted in the ground, it forms sprawling mounds nine to 18 inches tall2, which was precisely what I experienced. I would plant it again, but in a more open space. It was yet another lesson in “right plant, right place.” Photo credit: JC Raulston Arboretum


Mandevilla (Dipladenia sanderi) Every summer my mother planted this tropical vine in a container (with trellis for climbing) on her deck in Southeast Pennsylvania. In a short time, it looked spectacular. I’ve often considered doing the same, but the vines have become more expensive than I care to spend for a one-season plant. So, imagine my glee this spring when I noticed a new compact mounding cultivar for $6 in a big box store. I planted three in the ground; I mulched but have not been aggressive with water. They attract hummingbirds and butterflies. NC State Extension says they can be wintered indoors in a container.  


Portulaca grandiflora This is an old favorite of mine that I have not planted in a great while but is such a crowd pleaser. I think it might come to own this sloped spot (therefore, well-draining) among the native pink muhly grasses. There are varieties that flower in a single color, but I enjoy the ones with a variety of colors on one plant. So cheerful! Like evolvulus, the flowers close on cloudy days.

I’ll be looking to add more of these plants to my garden in future years. I am so grateful that some like it hot!


Footnotes, Resources & Further Reading

1. https://www.ahsgardening.org/gardening-resources/gardening-maps/heat-zone-map

2. https://plants.ces.ncsu.edu/plants/evolvulus-glomeratus/

https://extensiongardener.ces.ncsu.edu/extgardener-salvias-for-the-sage-gardener/

https://www.uaex.edu/yard-garden/resource-library/plant-week/begonia-dragonwings.aspx

Learn more about other plants listed above: https://plants.ces.ncsu.edu/

Unless otherwise noted, photos taken by A. Laine