Watering
The most important rule to remember about watering is, water thoroughly, and let the soil dry out slightly between waterings. Deep soakings help plants develop deep, strong root systems, able to withstand some neglect. Frequent light waterings result in a shallow root system, and encourage disease and weed growth. Keep in mind, though, that it is easier to overwater a shade garden than it is a garden in the sun. The lack of direct sunlight reduces the amount of evaporation, resulting in the need for less frequent waterings.
If too much water stays in the root zone for too long, root growth stops, and the roots die from lack of air. The longer air is cut off, the greater the damage to the roots. Damaged roots have little defense against the entrance of rot-causing organisms, and so the plant can die of root rot.
Monitor the watering of a shade garden by inspecting the soil after a typical irrigation. Using a shovel, check to see that the water has penetrated to a depth of 4 or 5 inches. The soil should be allowed to dry out somewhat before watering again.
Be especially careful to adjust automatic sprinklers if your shade garden adjoins a lawn area. Three or four waterings a week for the lawn may be fine, but if the sprinklers also water the shade garden it’s probably receiving too much moisture.
If you follow the advice concerning the addition of plenty of organic matter to the soil, you’ll also avoid most problems associated with water. Soil with a good structure is hard to overwater. Because of the porosity of such soil, water, even in large amounts, will drain through, leaving the all-important air in the soil.
Although the majority of shade gardens are prone to overwatering, there are a couple of instances where the opposite is true. One is where a canopy of leaves seriously retards rain from reaching the soil. Another is where shallow-rooted trees (willows or pines) compete for water. A more common situation occurs when rain is kept from reaching a planting bed next to the house because of wide eaves or overhangs. In both cases, pay particular attention to the amount of water the plants receive throughout the year. Plants in these situations can suffer from drought conditions any time of the year.
