People who grow houseplants and pay close attention to them will notice that, in mid to late February, they begin to grow quickly. What triggers this growth spurt is day length. The sun shining for longer periods each day slowly wakes plants from dormancy. Because they grow so fast during this period, they need more water and nutrients.
Six months later in mid to late August, the opposite happens. As days grow shorter, plants begin to slowly prepare for their winter dormant period. Above ground growth slows and though they still need water, plants begin to reduce their nutrient intake. This is why all fertilizing of trees, shrubs, roses and perennials should stop by mid August. This is also why mid to late August is an excellent time for planting trees, shrubs, and perennials.
Because plants don’t exhaust themselves by putting all their energy into growing foliage at this time of year their energy can be directed to strong root growth instead, and they become established much more quickly. As daytime temperatures cool and fall rains begin they will also need less watering. A shrub or tree planted during the heat of June and July may need watering every day but in late August once each week will usually do, and this greatly reduces a gardener’s work load.
An added bonus of fall planting is that many plants are on sale, so if you’d like more plants in your garden and want to cut the work of watering in half, now is the best time to plant.