Someone once asked me when the best time to irrigate was. My cynical answer was when it’s raining!
Technically the best time to water is before plants get thirsty and this is usually the morning. Watering in the evening is less ideal, as it leaves time for mould and diseases to develop. Simply sprinkling after a hot day is better than nothing, but no more than a band aid solution. Besides keeping seedlings constantly moist, the general rule for established plants is water “deep and infrequently” — kind of like an old married couples’ lovelife. But seriously, the average rainfall soaks in a just a couple of inches, so you can’t really count on it. So watering in the rain makes sense, so you can pay more attention to the younger shallow rooted vegetation when the weather clears up.
Different plants have different water requirements, and this too changes throughout the season and its life cycle.
Blueberries, for example, are a shallow rooted bog plant and love as much water as you give them. An established fruit tree, on the other hand, can have a root system as big as its crown, and may only need a good soak in a dry spell. Also, if you spoil your plants with constant watering, they will do what spoiled kids do for themselves… very little. You must let your plants search for that deep water, which is also where the most minerals are. Also a slightly stressed plant will tend to produce more, thinking its reproductive cycle is in jeopardy. This is a fine line that good gardeners closely monitor.
On the most basic level, plants need three things to survive besides light, a daily given. These are air, nutrients and, of course, water. Without water, there is no life whatsoever. Water is essential for delivering the nutrients to the roots.
Too much water for too long will suffocate the plants by filling in the air pockets in the soil. Too little and the cell walls dehydrate, causing wilting. Prolonged or frequent wilting will compromise or kill your plant.
Automated sprinkler systems are great for the suburban landscape and lawn, but are not practical for the small scale hobby farmer over several acres. A good gardener has an intimate relationship with his or her dependents’ needs. As I mentioned previously, these watering needs change from plant to plant and season to season. Grouping plants with similar watering needs is wise. Automation is convenient for a small area if you’re going away for a bit, but it’s like leaving your teenagers home with a stocked fridge. I prefer drip systems — they conserve water and you can let them run for a whole day to get that deep watering. Overhead sprinklers are prone to clogging, evaporation, uneven distribution, wind and even sun damage from magnifying the water droplets.
Growing plants is often like raising children. They need lots of attention when they are young, but eventually you need to quit spoon-feeding and let them find their way. You should still check on them when they’re grown up and offer a care package every now and then.