In The Garden With Kerry Heafner

As I write this in mid-August, it seems a fresh hell has gripped the southern United States.  I have never in my life experienced summer temperatures like this.  Back home in North Carolina, we thought a high of ninety-two was terrible!  Here in the ArkLaMiss, we welcome it!  I remember going to a Botanical Society of America conference in Montreal in August of ’97.  Lows dropping into the high forties at night in August?  I’ll take it!  Sleeping with the window raised in a dorm room at McGill University was like taking a week off!  There’s just no point.  We may not be adapted to temperatures like this.  But certain plants are. 

Desert plants are especially suited to these temperatures.  Leaves are much reduced to conserve water.  In cacti, leaves are reduced into spines or even long, silver hairs that not only help to conserve water, but also reflect incident sunlight.  Stems are succulent and adapted for both photosynthesis and water storage.  The actual metabolic process of photosynthesis is even modified to run some of the light-independent reactions during nighttime hours to conserve energy.

The Gulf prevents us from living in a desert and is the primary source of our impressive humidity.  Plants native to our area may not have the same adaptations to heat as desert plants, but they are more acclimated to these types of temperature swings than we might think.  For the most part, trees are still lush and green (for now).  But, if highs in the low hundreds are prolonged, we might see some deciduous trees move toward an early or premature dormancy.  They might start dropping leaves to conserve water.  Leaves that hang on through fall with the reduced daylight hours may not exhibit brilliant colors like they normally would under average temperatures and rainfall.  Put simply, trees may look worse for wear a bit earlier than usual.  You can help trees in your landscape out by watering them at dripline.  This is approximately where the feeder roots are located.  Simply lay the end of the hose on the ground and let water seep down to the roots.

All of this begs the question, “What WILL survive this heat?”  Here are some options.  

Seasonals:

• Tropical Hibiscus (Hibiscus rosa-sinensis).  These longtime favorites are different than our native, hardy hibiscus (H. moscheutos, H. coccinea and cultivars), which dies down every year.  Tropical Hibiscus is reliable color all summer long, no matter the temperature, and there are few plants better for attracting hummingbirds to your landscape!  Perfectly at home in a container, Tropical Hibiscus requires little effort other than being situated in full sun and keeping the growing medium moist.  A slow-release fertilizer application occasionally won’t hurt, either.  Tropical Hibiscus is available in a wide array of brilliant colors and as single or double blooms, so you’ll have no problem finding something that suits your landscape.

• Annual Vinca (Catharanthus roseus).  Annual Vinca is a summertime workhorse when it comes to maintaining bright color in ornamental beds or containers.  Its drought resistance rivals that of Angelonia (keep reading!), and bright color will be abundant until the first major frost.  Creeping varieties make great “fillers” and “spillers” in hanging baskets.  Upright varieties will make any bed in a sunny location pop.  Annual Vinca is at home in most ArkLaMiss soils, preferring a pH ranging from 5.5 to 6.0.  

• Summer Snap Dragon (Angelonia angustifolia).  You’ve probably seen Angelonia planted in beds on commercial and business properties and wondered, “How do those plants survive the hot baking sun?”  They do, and they will do the same in your beds all summer.  Angelonia is as drought resistant as it gets and doesn’t mind soaring temperatures.  The ‘Serena’ series and ‘Serenita Raspberry’ are Louisiana Super Plant selections and will be reliable bright color until you switch them out for fall color.

• Succulents of all kinds are adapted to these hot, dry conditions, and you’ll find no shortage of varieties to choose from at the garden center.  Portulacas are succulents that will flower all summer long and withstand these hot temperatures.  This includes Purselane (P. oleracea) and Moss Rose (P. grandiflora).  Sedums, also, are great choices for hot, dry conditions.  Look for the Louisiana Super Plant selection ‘Lemon Ball’ Sedum.  Its bright chartreuse green foliage contrasts nicely with yellow flowers.  If you’re wondering what the “spiller” in the baskets on Antique Alley is, it’s Dorotheanthus bellidifolius ‘Mezoo.’  Also called Livingstone Daisy, ‘Mezoo’ is extremely tolerant of drought and heat and flowers all season.

It is most certainly not the ideal time to install trees and shrubs into your landscape, but when that time rolls around there are plenty of options to choose from in anticipation of next summer’s inferno.  Generally, plants that have leaves with thick, waxy cuticles are more heat and drought tolerant than trees and shrubs with thin, pliable leaves.  For superior heat and drought tolerance, natives are the way to go!  

• Evergreen species of Magnolia, such as Southern Magnolia (M. grandiflora) and its cultivars like ‘Teddy Bear,’ ‘Little Gem,’ and ‘Bracken’s Brown Beauty’ are all great choices.  Sweetbay Magnolia (M. virginiana) can be either evergreen or deciduous but is also native to our region and is adapted to our climate.  

• Evergreen Hollies (Ilex cornuta, I. vomitoria, I. opaca, etc.) also have waxy leaves and will are very heat and drought tolerant.  Hollies have the added bonus of being excellent choices for attracting pollinating insects.  Both native and honeybees flock to the tiny, white flowers in spring.  Garden centers are seldom in short supply of old standards like ‘Needlepoint,’ ‘Nelly R. Stevens,’ or ‘Yaupon’ hollies, and a host of other cultivars. 

• Willow oak (Quercus phellos) is a deciduous native and is a Louisiana Super Plant selection.  Willow oaks grow fast and will provide a lot of shade at maturity.  Wildlife will take advantage of the habitat and the small, pumpkin-fleshed acorns every year.  Fallen leaves can be used as mulch in the vegetable garden or in ornamental beds or can be chopped up and added to the compost pile.  Willow oak is a bottomland species but is extremely tolerant of high temperatures and dry conditions.  They do need plenty of space, so take that into consideration if planning to install one on your property.  Other native oaks are also great additions to the landscape if they have enough room to fill out uninhibited.   

• Texas Sage (Leucophyllum frutescens) is seen often in ArkLaMiss landscapes, but it’s still kind of a “best kept secret.”  Though it prefers more arid conditions than we typically have, it will still thrive in our oppressive heat.  Install Texas Sage in the sunniest locations in your landscape and basically let it go.  This is a plant to keep in mind for a xeriscape.  It blooms profusely after a rain or with frequent watering, which isn’t a requirement.  And, Texas Sage will attract hummingbirds and pollinators to your garden in droves.  I’ve often said Texas Sage is underutilized in our area.  This long scorching summer may be a good reason to remedy that.

Folks, be careful out there.  Stay hydrated, take frequent breaks, and make sure outdoor pets have access to shade and plenty of fresh water.  Be sure to join me on Tuesday afternoons at 4:30 on Louisiana Living, and on Tuesday and Thursday mornings at 8:45 on KWCL 96.7 FM for the television and radio installments of In the Garden.