How to Create a Landscape that will Survive a Hot, Dry Summer
Drought-hardy plants are essential in warm weather climates
Caring for and establishing a garden or landscape in the summer months can be difficult, especially for those who live in the Southeastern U.S., where seasonal temperatures frequently rise into the upper 90s. With summer beginning just a few weeks ago, this year is certainly no exception. What's more, many throughout other parts of the country are experiencing record heat and drought conditions due to a lack of rainfall and an unusually mild winter. That being said, it has become increasingly important for homeowners and gardening enthusiasts alike to understand which plants are best suited for warm and dry conditions.
Included below is detailed information about how to choose "drought-safe" plants - what to look for if you're unfamiliar with certain species of plants, and how plant biology contributes to plant hardiness in extreme weather. Also included is information about how to prevent loss of plant life through understanding how best to water them, and how to conserve water when faced with drought conditions. And lastly, listed at the end of the article are several plant species that have been researched extensively and are known to survive (and even thrive) in the hot, dry summers that are so often characteristic of a summer in the southern U.S. Read on...
Take advantage of plant biology in drought conditions
All living organisms are affected by nonliving things, called abiotic factors. This is something I routinely discuss with my high school biology students, as it is pervasive among all species on Earth. Plants are certainly no exception; what's more, because they cannot move freely from place to place, the abiotic factors found in their environments may have an even greater effect on their overall well being and survival.
There are several things most people understand about plants, and certainly, if you are reading this article and have any experience gardening, I will assume you are in this group of individuals. We know that all plants need water, sunlight, soil, and sometimes, chemicals in the form of fertilizers or pesticides, to grow and thrive in any location - after all, this is part of what makes a plant, a plant! It makes sense then that a lack of any of these abiotic factors can spell trouble for a plant.
For instance, when a native plant is exposed to above normal temperatures or a lack of rainfall, it becomes stressed, just like we become stressed when something seems to be "out of whack" in our lives. As humans, we have the ability to address stressful situations and correct the problem, but plants are not able to do this. Instead, plants' reactions to stressors, such as drought conditions, are usually defense mechanisms that are initiated within the roots.
Roots have a very specific job - to absorb water and minerals (such as nitrogen and phosphorous) from the soil, and transport them through the stem and toward the leaves. Therefore, a strong root network is essential to a plant's survival in any environment. When stressed by extreme temperatures or a lack of rainfall, plants will attempt to absorb as much water from the soil as possible, which means that the roots will actually grow or move to "look" for water.
You can take advantage of this biological phenomenon by watering plants and flower beds less often, but with a greater volume of water. Plan to water annuals and perennials about 6 inches deep, and trees and shrubs 12 inches deep. Repeat this and water again only when you notice dry topsoil. This should help to promote the development of stronger root systems, and thus, overall plant viability and survival in the long run.
In addition to the root systems, plant leaves are also essential for survival and viability. Leaves are organs that contain the machinery to convert sunlight into food energy (sugars), a process known as photosynthesis. While important for plant growth, photosynthesis is a process that is actually essential for all living things found on Earth, as plants provide all of necessary energy for any ecosystem.
The major workhorses of photosynthesis are chloroplasts, which are found within the leaf cells of plants. In addition to giving leaves their green color, chloroplasts perform photosynthesis and produce the oxygen that humans and other species must breathe, in order to live. This oxygen is released from the plant through tiny pores on the underside of leaves, called stomata. Occurring simultaneously, water is lost, or evaporates from these pores, through a process called transpiration.
Loss of water through transpiration can be heightened on hot, dry days, when plants may lose up to 90 percent of the water taken up through the roots. In general, the higher the temperature and humidity level, the greater the water loss for a given plant. Address this by watering wisely, as described above, or choosing plant species that are suited for survival in extreme conditions.
How to choose the best plants for your garden
The best advice I can give you - stick with native plants. This means those plants that are naturally found in the area in which you live. Think of it this way - there is a reason they grow in and around in the area in which you live! These plant species have developed in a manner that allows them to withstand the seasonal temperatures, humidity levels, and rainfall amounts that are typical for your area.
So, where to get native plants that you can actually plant in your garden? Fortunately, the big box retailers like Lowe's and Home Depot routinely sell plants that are suited well for specific regions of the U.S., so it shouldn't be difficult to find plenty of options that will suit your needs. Definitely make sure you do some research before purchasing anything, though, as there are usually many different species of full sun, partial sun, and shade-loving plants.
If you have difficulty finding native plants, or want to use other plants that are not native to your region, there are several characteristics that most drought-hardy plants share in common...
1. Waxy cuticle Similar to animals and other living things, over time plants have developed certain adaptations that allow them to survive under what are typically thought of as stressful conditions. Plant biologists have found that in general, plants with thick, waxy cuticles are better suited for hot and dry environments. So, what is a cuticle? The cuticle of a plant can be thought of as the skin found on the leaves. Since leaves play a big role in photosynthesis - the energy-producing process that is essential for life - they also are a major site of water loss, a process called transpiration. Researchers now understand that the waxy cuticle, that thick, water-repellent layer, is helpful in preventing excessive water loss and damage to plants exposed to drought conditions.
2. Fuzzy leaves Some plants appear to be unique in that they have tiny hairs all over their leaves and sometimes, their stems. However, this is a characteristic that is widely seen in a variety of plant species, and especially among plants that are well-suited for extreme conditions. In general, the more pronounced the hairs on the leaves, the more protected the leaves, and therefore, the more likely that the plant can withstand extreme temperatures. That being said, most plants with fuzzy leaves tend to also have waxy cuticles. If you find one of these, it may be worth your while to try it in your garden!
3. Thick stems Similar to waxy cuticles, thick stems are also composed of many additional layers of protection, which can aid in plant survival. Within the stem structure of any plant is a vascular system - a network of channels and tubes similar to the veins and arteries that make up the human cardiovascular system - the major function of which is to transport materials. Water moves up the plant, from roots to leaves and flowers, through a structure called the xylem, while the plant's "food" (sugars produced by photosynthesis) moves in the opposite direction, down the phloem, from leaves to roots. In terms of water transport, the thicker the stem, the bigger the xylem, which allows better water movement and storage.
A list of 10 drought-hardy plant species you may want to try in your garden
In addition to plants that are native to your region, the following may prove to fare well in your garden...
1. Rudbeckia (partial to full sun)
2. Hydrangeas (partial to full shade)
3. Hosta lilies (partial to full shade)
4. Knockout shrub roses (partial shade to full sun)
5. Trumpet lilies (partial sun)
6. Zinnia (full sun)
7. Lavender (partial to full sun)
8. Coreopsis (partial shade to full sun)
9. Lamb's ears (partial shade to full sun)
10. Sedum (partial shade to full sun)