Watering During Hot Spells

Despite the cooler June weather, it is dry out there now and your plants and trees need water. During a run of very warm days we need to be aware of the importance of thorough watering, as well as how to water wisely. Watering is an art, and when done well, will help plants thrive and at the same time will preserve this precious resource. Unfortunately, many folks are not sure how or when to water, and as a consequence, many plants are either under stress or suffering from diseases like mildew and botrytis.

If you have a choice, always water in the early morning as the temperature is on the rise. Doing so will allow the plants to make the most efficient use of the water during the warmest part of the day, and they will not transpire the moisture away as they will with evening watering. It will also allow the foliage to be dry at night, preventing mildew and other related problems.  

When you water, make sure that you water thoroughly and that the water penetrates deep into the soil so the moisture goes down to the roots where it is needed. This is especially true for trees and shrubs. Thorough watering will encourage roots to grow deep and be less dependent on frequent watering. One of our greatest concerns is for the thousands of hedging cedars surrounding many homes. After a few years, we tend to forget about them, not realizing they are very shallow rooted, and like rhododendrons, need adequate water to keep them healthy and not stressed out. Shade and flowering trees and shrubs need to be watered around their drip lines where the roots can absorb the moisture. This is where soaker hoses, used at least on a weekly basis, come to the rescue.

Lawns need to be watered only once a week during hot weather, but again, make sure you let the water penetrate down to the roots so they grow deep and the grass becomes more self-sufficient. This is why aeration of lawns in the spring and fall is so important. Aerating and then applying a ¼” layer of sharp sand will allow maximum penetration of water and will help your grass roots grow deep. The recent research from the turf industry suggests keeping your grass cut lower, at approximately 2” (5cm) in order to reduce evening transpiration and to conserve moisture. A little browning is not a bad thing. When the rains return, the green colour will reappear rather quickly. 

Vegetable gardens are the most challenging in the heat. If you always water in the morning and water only the root zones of all your plants, this will go a long way to prevent blight on potatoes and tomatoes. When you water, please use a water breaker with at least 400-1000 holes at the end of your hose for the most efficient distribution of water into the soil. Using a wand always makes watering much easier as you are not constantly having to bend over. Shallow and frequent watering makes not only your vegetable plants but also your annuals and perennials less self-sufficient and more dependent on watering—so water deeply to push those roots down.

Planters and baskets offer a different challenge, especially when it’s hot. Water them thoroughly in the morning so they’re less stressed during the day. But before you water them again, feel the weight of the basket and make sure it feels light. If it feels heavy, it is already wet enough, and you should wait until it dries out before watering again. Over-watering is worse than under-watering because the roots may rot with too much water, especially with fuchsias. With planters and baskets, it’s important to feed more frequently because you’re leaching out nutrients every time you water. This is where slow-release fertilizers, like 14-14-14, play such an important role in keeping your baskets continually fed, especially when we water so often at this time of the year.

Gardening should be enjoyable, so when watering, do it less often but more thoroughly. Focus on watering the root systems and try to water in the morning for the most efficient use of water. Soaker hoses and drip systems are the most effective way to save you time and to use less water.