During a summer of crazy hot weather, much like forecasters are anticipating this year, plant material can get stressed out in a big way. These organisms live very cyclical, less dynamic lives than animals do. Plants thrive in their ideal, native environments, which are not typically the exact environments they are planted in. Over time, plants have moved throughout the world, but not usually on their own.
The migration of plant material over time has been primarily due to animal intervention, mostly by humans. Unlike humans, who can move around and adapt to survive in every climate imaginable, plants do not have the ability to move from warm to cool climates, and vice versa.
Plants are zonal, which means each species has specific climatological zones that it can survive in. However, within these zones, which are primarily temperature driven, the same plant might do much better in some places than it does in others. In the Front Range of Colorado, primarily a Zone 5 region, the plant pallette is much more limited than it is in Iowa or Nebraska, which also fall into Zone 5. Most of this is due to the difference in precipitation rates.
Even if two parts of the country fall into the same zone, precipitation and soil type can increase the rate of evapotranspiration that a plant experiences, and stress can kick in a lot quicker in the drier areas with soils that drain more quickly. Fortunately, there are some practices that a property owner can follow to help increase plant survivability.
Proper use of soil amendments is the first line of defense. Soil types in certain areas that are sandy and quick-draining can be a big problems for certain plant types. Soil amendments, such as compost or even polymers can aid in water retention. Thoroughly mixing these amendments in can increase survivability and if done properly, does not necessarily need to be an annual practice. Proper use of wood mulch can also add organic material to the soil as it breaks down from one year to the next.
Another good practice is to make sure that gardens and planting beds have adequate canopy coverage. In addition to the aesthetic appeal of reducing big gaps between plant materials, a consistent canopy between the tops of plants and the ground will reduce direct sun exposure with the soil and slow evaporation. Make sure that plants slightly overlap without crowding each other out to help reduce sun exposure to soil.
A final practice, which is obvious but often overlooked is properly timed watering. When a landscape professional sees sprinklers running during the hottest part of the day, it will just about drive him or her nuts. Very hot weather can actually evaporate some water before it even hits the ground, and when it lands on leaves that are in direct sun exposure, it can actually have the same effect as a magnifying glass. This can cause the plant to get even hotter than the ambient temperature, further increasing evapotranspiration and stress. It is important to schedule watering between dusk and dawn to most efficiently maximize water usage.
Hot, dry summers can have many adverse effects on plant material. Following the above steps can help reduce plant stress and increase survivability during these periods of time.