The past two years have been very challenging years for gardeners. I find myself wishing for a “typical” year as we seem to have swung from one extreme to the other. Last year was a complete wash out, with many crops not coping well with the seemingly constant rain. This year we go to the complete opposite – dry! I cannot believe how fast my crops are literally wilting after I water them. I got taken by surprise by the extremely hot weather a few times, and while spending too much time at work, ended up missing a few waterings. It seems there is little forgiveness for this. How many times I uttered the phrase “but it was supposed to rain” as I looked at struggling plants. A lot of how well your crops will cope with weather extremes depends upon your soil type. Heavy clay soils tend to hold on to moisture; in wet years this can lead to a lot of fungal diseases. Sandy soils dry quickly, so in years of little rain it can be difficult to provide enough water. If you have a nice loam soil, then you have the equivalent of Goldilocks’s porridge that was “just right.”

This winter squash and corn patch benefits from afternoon shade. Note the wilting plants in the front left of the photo, and the bone-dry grass in the foreground. Photo by mrl2022.

I wrote an article a year ago where I commented about how well some varieties of green beans coped with the wet weather. It is interesting (making the best of it) to see how those same varieties of beans coped with the dry conditions. Although not a formal scientific study, the observations of these plants are notable. I generally plant three varieties of bush green beans: green, yellow, and purple. These are the same specific varieties I plant each year. During the wet year, the green were the first to die off, followed by the yellow.  The purple seemed to tolerate the wet weather quite well and produced a huge crop. Now that we have a dry year, the opposite seems to be holding true. The purple was the first to die off, the yellow are struggling some, but the green seem to be thriving. In a “normal” year, I have all three varieties producing a large crop. It is only in times of extremes do the tolerances become important. Most farmers choose varieties of crops that are well suited to their particular set of growing variables (soil, sun, soil chemistry, cultural habits, etc.). Interestingly, I have one variety of pole green beans that seemed to thrive in both the wet and the dry years. 

These family heirloom pole beans seem to thrive in all types of weather. No wonder they have been in cultivation for hundreds of years! Photo by mrl2022.

Watering sounds easy, but it can lead to trouble. Frequent irrigation with no rain can, over time, lead to salt accumulation in the soil. This is because when water evaporates, the salts dissolved within can stay behind. We usually do not see this here in the northeast, but the southwestern United States can. Due to time limitations we all suffer from, it is tempting to water a short sprinkle frequently, but this is not good for your plants as it encourages shallow roots. It is better to water less frequently, but for a longer period of time to encourage deep roots. Deep roots help the plant survive during times of drought. Having said all that, I have never seen the soil so dry as I did this year. I water with a sprinkler, and this year I had to increase my watering duration by 50 percent to adequately wet the soil. If your garden is small enough, it is a good idea to use drip irrigation. It wastes less water by putting it right by the plants. This requires running plastic piping throughout your garden, periodically poking a hole in it, and running a drip line to each plant. It is somewhat tricky to then rotate your crops the following year as the plumbing will generally need a different configuration. Careful planning may allow for some flexibility in this situation. Drip irrigation has the added benefit of not wetting the leaves, which can cause burn spots in some plants, and contribute to diseases in others. A less expensive alternative is a soaker hose which just seeps water along its entire length. This is simply snaked through the plants.  Remember though that watering is expensive! If you are on city water, you will have a substantial increase in your bill, and if on a well water, higher electricity costs. This assumes your well has enough water to keep up with the increased demand. The bigger the garden, the more water needed.

The last thing I wanted to comment on was shade. Although I generally think of shade as an enemy of agricultural crops, it can certainly work to your advantage in certain situations. This year, afternoon shade has helped keep some crops from drying out. My winter squash and corn seem to be thriving with some afternoon shade (this is the hottest time of the day!). The plants in my kitchen garden do not seem to wilt if in the shade of a poorly placed mulberry trees (I did not plant it so close to the garden; it was there when I purchased the house). Many times, gardeners will use shade cloth to cool heat-sensitive crops like lettuce. Shade may decrease the temperature by ten degrees. This can help the lettuce resist bolting. Don’t forget to select varieties resistant to bolting as well. Be careful of shade though. Hot, wet, and shady can lead to powdery mildew in a number of our favorite ornamental and food plants (phlox and zucchini for example). Most of our agricultural plants need six hours or more of sun each day.

This variety of cucumber thrived in last year’s constant rain, but struggles to hang on during our current dry weather. Photo by mrl2022.

The thing to keep in mind is that these extremes do not usually happen. You may get a few years in a row like we have had, but there are many more typical years to come. Use these years to your advantage and learn what you can. Try not to let yourself get frustrated. I find myself thinking about my soil composition more now than ever. This would be a great time to get your soil tested. Adding compost can help aerate clay soils, and hold moisture in sandy soils.  Compost not only adds nutrients to the soil, but also improves nutrient retention. I like making observations and comparisons in these types of years. For example, in last year’s wet, the cucumbers grew like crazy. In this year’s dry, they have not grown much at all. Apparently, cucumbers like a lot of water (but not soggy soil which leads to disease). Experiencing and now knowing this can help me grow better cucumbers in years to come. So many people rate their garden as successful or not by the amount of produce produced in a given year. Of course, each year this is the goal, but when you learn more about your soil and plants this can help you grow more crops during your entire lifetime. To me, the knowledge is the most valuable part!

Matt Lisy

With the dog days upon us, getting adequate water to our gardens can be a concern. Water is essential to all life. Plants use it to transport nutrients and to maintain turgor – the cellular pressure that keeps soft tissue from wilting.  Plants absorb water (containing soluble nutrients) through their roots and ultimately release it into the atmosphere as vapor through small pores (stomata) on the undersides of leaves in a process called transpiration. Although invisible, the cumulative volume of water transpired by Earth’s plants is prodigious, producing 10% of the atmosphere’s water vapor. One large oak tree can transpire 40,000 gallons per year. Drought stress occurs as transpiration continues and soil moisture is exhausted.

Wilting muskmelon plant
Photo: Erika Saaku, Iowa State

Transpiration rates increase with:

  1. High temperatures
  2. Low humidity
  3. Wind
  4.  More soil moisture
  5. Larger, thinner leaves

Hydrangea or squash leaves wilt on hot, dry, windy days because the transpiration rate of these large-leafed plants is faster than the plant’s ability to take up available moisture from the soil.

At the other end, if a plant’s root system is compromised or undeveloped, extra care must be taken to ensure survival. The process of digging and transplanting exposes roots to the air, damaging or destroying delicate root hairs. Recovery can be difficult with the additional stress of hot weather. Provide shade and plenty of moisture to allow these essential single-cell structures to regenerate. In some cases, cutting back some of the leaf mass to reduce water requirements is advisable.  Old-fashioned advice for transplanting instructs: “water once a day for a week, once a week for a month and once a month for a year.” A very inexact guide to be sure, but a good reminder that transplants have high water demands at first and need to be weaned gradually over time.

Container-grown plants often have root systems a fraction of the size of an equivalent plant growing in the ground. Regular watering is a must, particularly when  containers are made of porous clay or fiber. Potting mixes are commercially available that contain polymer crystals which can dramatically increase the water-holding capacity of potting soils in containers.

Measuring irrigation output

“Deep and Infrequent”

This mantra of watering advice emphasizes the need to train turf grass and landscape plants to develop deep root systems in search for water. Shallow, frequent watering encourages the growth of roots close to the soil surface, making the plant vulnerable to drought stress.  Shrubs and trees with weak, superficial root systems are also more likely to topple over in a windstorm.

Root growth of turf ceases at soil temperatures of about 70°, so lawns should be encouraged to develop deep root systems during the cool weather of spring and fall. Summer watering of lawns is triage; keeping the patient stable until temperatures drop. Overwatering results in excessive growth and increased risk of fungal disease, while wasting water and fertilizers that can potentially contaminate waterways.

Mulch conserves soil moisture as it suppresses weeds and dresses up the garden.  Organic mulches mimic the natural duff on the forest floor, creating a hospitable environment for microbes, fungi, insects and worms as they perform their function of decomposing organic matter and releasing nutrients.

Managing water in the garden is a skill that gets honed over time, as the gardener develops sharper instincts for plant requirements. Water is also a surprisingly efficient and environmentally sound way of ridding plants of some insect pests such as aphids and spider mites – simply knock them off with a forceful spray from the hose. Regular flooding will discourage ground-dwelling bees and wasps (yellow jackets) from nesting in inconvenient areas.

Water makes the garden more pleasurable for people and animals alike. Bird baths, gurgling fountains, lawn sprinklers for children or ponds with fish and frogs create a richer environment and a cool oasis of refreshment on a hot summer’s day.

Children swinging in sprinkler, 1964
Photo: Museum of History & Industry, Seattle

J. McInnis