Summer Proof the Garden

The doldrums have arrived. Gardening is at a minimum. I prefer to be inside, reading my newest garden magazine. Outside, plants may be loosing their vigor with bright green leaves fading to pale blueish gray, leaf edges crinkled, leaves dropping — all signs of heat stress. Meanwhile, bugs select the weakened plants for midsummer's wildest party, sucking and munching and having an orgy with all their friends and relatives. What's a gardener to do?heat stressed leaves

Don't let the doldrums get you down! Here are ten things one can do to summer proof the garden:

1. Choose the right plants. Many ornamental plants now have heat zone recommendations as well as hardiness zones listed on their tags. Developed by the American Horticultural Society in the late 1990s, the heat zone map identifies 12 heat zones in the US. These heat zones are based upon how many days a year the temperature rises above 86 degrees, the temperature when plant cells begin to deteriorate. I am in heat zone 8, which means there are 91-120 days when temperatures rise above 86. Look to see if a tag has two ratings for a given plant, such as 3-7/4-6. The first set of numbers indicates the plant is winter hardy in hardiness zones 3-7, and the second set of numbers indicates the plant will survive summers in heat zones 4 through 6. Remember the hardiness and heat zone maps are two different maps, so one needs to know both zones for one's location. I am on the edge of hardiness zones 7b/8a, but I am firmly in the middle of heat zone 8. There are plenty of plants that can take my winters but not my summers! Replace plants that die with others that are more likely to survive. Native plants are usually reliable, because they are well adapted to both winter and summer conditions.

2. Another thing that you can do to summer proof your plants is to add compost to the soil. This improves soil texture, creating large pores for water movement and air infiltration. Roots can also spread more easily, allowing the plant to reach nutrients and moisture. One trick to help retain moisture in sandy soil is to add clay based kitty litter.

3. Add a 3-4 inch layer of good organic mulch around the plant, but avoid piling the mulch directly against the base of the plant. I use a lot of pine straw, which complements my naturally acid soil. Avoid artificial mulches or gravel, which will radiate heat around the plant and is more suitable for desert type plants. 

4. Mow lawns high. This allows more leaf surface for photosynthesis, the process by which plants turn sunlight into energy. Do not fertilize lawns, except with a weak water based solution or with a top dressing of compost. 

5. Water deeply, less often. Frequent shallow watering encourages shallow root growth. Early morning watering is best. Drip irrigation systems winding their way through the plants are ideal. Bury them under the layer of mulch.

6. Group plants according to their water needs.

7. Windbreaks can protect plants against harsh summer winds. Trees, hedges, and fencing are options. Fences should allow air movement through the structure. Solid fences can create heat traps. 

8. I like to mix up a summer tonic for my garden. This consist of 2 tbs. of Epsom salts per gallon of water. To this I add fish emulsion or a seaweed fertilizer, prepared according to directions. The Epsom salts provide magnesium and sulfur, which promote photosynthesis. Fish emulsion and seaweed fertilizer supply many trace elements, amino acids, and enzymes that promote plant health and stress tolerance. I apply this to the soil around just about everything in my garden, especially those plants showing heat stress.

9. Provide shade during the hottest part of the day. You can make temporary shades out of shade cloth or other materials. I have seen colorful umbrellas propped here and there in a garden, giving relief to hydrangeas and other heat stressed plants.

10. Move plants in pots to more protected locations.This recent view of my lawn and garden shows that, so far at least, my garden is coming through this year's summer without too much heat stress.It may be tempting to ignore the garden when the summer doldrums strike. There have been years I wanted to give up and let the weeds have it. Don't! Early morning or late afternoon strolls give you an opportunity to check out plants when the temperatures are a bit cooler, and that is also is the best time to get garden chores done. And if you have summer proofed your garden, you and your plants can stay happy, even when the heat and humidity soars.

Yaupon Holly: An Unsung Hero

I first purchased yaupon holly because I wanted something that would not die. I was frustrated with azaleas and other plants that had suffered in the summer heat and bright sun of the front garden. I wanted an unfinicky plant to provide evergreen structure to the garden, and, among all plants in my garden, it has succeeded beyond my expectations.

In 1993, a blizzard, a once in a lifetime experience here in the Deep South, dumped three feet of snow atop recently planted 'Compacta' yaupons, a dwarf variety in the front garden. Though many other plants were damaged, the yaupons were unfazed. Since then they have patiently endured blazing heat, draught, and torrential rainfalls. A native of the southeastern USA, this is one tough plant that suffers from commonality but nevertheless continues on as an unsung hero.

Top left: A summer view of yaupons amidst other shrubs growing in the front garden. Top right: In a fall view of another part of the front garden, dwarf yaupons grow in association with silvery artemesia 'powis castle' and nandina 'firepower'. A brilliant Japanese maple grows in the background. Lower left and right photos both show dwarf yaupons growing in the woodland garden, late winter. Note the looser, more natural form of these less pruned specimens.

Yaupon holly, Ilex vomitoria, acquired its botanical name from a Native American custom of using the plant to make a strong tea for use in certain purification ceremonies, which involved vomiting. Not a glamourous name, but I think they are beautiful. Yaupon holly may grow as an evergreen shrub or as a small upright or weeping tree. The females produce bright red berries that are an important food source for many birds. We have a weeping yaupon holly tree near the glass doors in our kitchen, and it is a joy to watch the birds in this tree in late winter. I once saw a flock of mockingbirds strip it of its berries in a single day.We have a good view from our kitchen table of this weeping yaupon holly and its popular berries.

The shrub forms look a lot like boxwoods, with small glossy leaves, dark green above with slightly paler undersides, and the dense, slow growing shrubs are easily pruned into hedges of various shapes. My oldest 'Compacta' matured to about five feet tall and wide. At first I planted my immature plants too close together and eventually had to remove about half of them because they were growing into each other. Yaupon is a common landscape plant, and I often see rows of these things in front of pharmacies and quickie marts, all grown together to form undulating worms. Not the look I was after! The good thing is that I only paid a few dollars each for small ones, so I didn't feel too guilty.

Yaupons grow best in partial shade to full sun in hardiness zones 7 to 10 and will grow in clay, loam, and sandy soils. They tolerate salt spray, wind, and heat and adapt to a wide variety of soil moisture conditions. They are rarely bothered by disease or pests and succeed when many other evergreen hollies struggle.

I like the looser look of a minimally pruned yaupon, and this is how they grow in the woodland areas of my garden. I only snip wild shoots once a year on these, and I would prefer to do the same for the ones in the front garden. But this is where marital compromise has asserted itself. Lou is the owner of a power hedge trimmer, and he loves to use that thing. I have given the ancient boxwoods that grow around the foundation of our house over to him, after clear instructions on how to prune them. He does an admirable job, though sometimes scalping them too severely for my taste.

But a man with a power tool is a man on a mission, and sometimes he casts his eyes upon my yaupons, and if they are growing out of bounds according to his taste, he is sorely tempted. More than once he has sheared them into harsh balls I despise. I prefer to use a good quality manual hedge trimmer, a much more precise tool that gives a softer look and damages the leaves less. Power trimmers, though faster, leave brown edges where they rip through the leaves.

I trim the dwarf yaupons after new growth begins in spring and again in fall as needed. It is important to trim yaupons, boxwoods, and similar shrubs so that the widest part of the plant is at the bottom, tapering slightly toward the top. This allows sunlight to get to the bottom branches. Too often shrubs are pruned only across the top, resulting in sparse or even naked bottoms, not a pretty sight!

I hope you are having a great week!   Deborah