By: Russell Stafford
Plants need moisture to survive and thrive (as your plants will be all too willing to demonstrate if you’re too sparing with the watering can). Give their roots enough water, and their breathing leaf pores (known botanically as stomata) can remain open for business, drawing up nutrient-rich water from the soil and taking in carbon dioxide from the air. Give them too little water, and they will languish.
But as with most good things, too much water can be problematic as well, leading to poorly aerated soil and suffocated roots. Here are eight tips to help your plants keep happily hydrated (and not deathly dry or sickeningly soggy) this summer and beyond:
1. New plantings require special attention, especially in the heat and drought of summer. Root balls of container-grown plants are almost always coarser and faster-drying than the soil into which they are planted. Consequently, they can become dust-dry even when the surrounding soil appears to be sufficiently moist. Monitor them frequently, watering when necessary. Bare-root and balled-and-burlapped plants lose most of their roots during the digging and transplanting process, and are thus at even greater risk of drying. Plant them in spring before leaf-out (or in fall when the air is cooler and the soil is still warm), and water them regularly until they’re established. In all cases, apply 2 or 3 inches of bark mulch to new plantings to retain moisture and to deter soil compaction.
2. Loosen the outer roots of root-bound container-grown plants, to allow contact with surrounding soil. Mound soil around all newly installed plants to form shallow water-retaining “saucers”.
3. In clay soil, planting holes can become root-drowning bathtubs. Add organic matter (such as Fafard Premium Natural & Organic Compost Blend) to gradually improve the texture and drainage of heavy soil. In the short run, create raised mounds for new plantings.
4. Know the moisture requirements of plants before you buy and install them. Many ornamental plants from dry-summer regions such as the Mediterranean and Central Asia are intolerant of damp warm-season conditions. Conversely, moisture-loving species such as golden groundsel (Ligularia dentata) and swamp azalea (Rhododendron viscosum) begin to wilt at the slightest hint of drought.
5. Even established shrubs and trees may need watering during prolonged drought. Deep watering is not necessary and can be counter-productive, given that most roots are in the upper few inches of soil. Rather, water frequently and shallowly, to keep the upper, most drought-susceptible roots from drying. “Deep” watering may cause plants to produce new, succulent growth, thereby compromising their drought resistance. Mulch (see above) will lessen the likelihood of drought stress in established plantings, just as it does in new ones.
6. Water in the morning before the heat of the day, or at other hours on cloudy days. Use a hose and wand or watering can to directly irrigate recently installed plants. Soaker hoses, drip systems, and other irrigation methods that directly contact the soil are ideal for established plantings. Sprinklers waste water.
7. For potted plants: water when the potting mix reaches the appropriate level of dryness (typically when the surface of the mix is dry). Alter watering frequency as necessary for plants from arid or damp climates. Species native to tropical forests and other humid habitats may benefit from misting, or from being placed on a pebble- and water-filled humidity tray. Use a suitable soil mix; for example, many orchids prosper in a bark-rich mix such as Fafard Orchid Potting Mix, and moisture-loving species will appreciate a humus-rich medium such as Fafard Natural & Organic Potting Mix. Relatively deep, narrow pots drain (and dry out) more rapidly than shallower, wider pots.
8. Contrary to popular gardening myth, layering gravel or other coarse material beneath the potting mix does not increase its drainage, but rather decreases its aeration and depth. This practice is detrimental rather than beneficial for most plants.