Match your irrigation system to your plants
Watering your garden need not be complicated or time-consuming; in fact, easy-to-use hoses or soaker hoses (perforated on one side, or porous overall) may be your best choice for some plants. The list that follows pairs plant groups with the watering methods that work best for each. In-ground sprinklers are certainly best for lawns.
Drip-irrigation systems (made of PVC pipe and slender tubing with emitters that deliver water directly to individual plants), managed by automatic controllers, can be the most convenient method for irrigating flower beds, rows of vegetables, and even shrubs and trees, especially when you’re on vacation.
However, both systems must be mapped out and, in most cases, installed before you plant, so the list that follows focuses mainly on manual devices and techniques (building basins and furrows of soil around plants, for instance, to direct water to the roots and help avoid runoff). If you plan to install a larger automated system, it is best to do so before a seasonal planting.
For a small lawn, hose-end sprinklers can work well.
Plant in rows with furrows; build basins around large individual plants. Hand-water.
Use soaker hoses on flat ground.
Seedlings and vegetables that are flowering or setting fruit need more water than mature ones.
Planning ahead? A drip-irrigation system is the best method. Group plants with similar watering needs.
ANNUALS AND PERENNIALS
Use soaker hoses or hoses slowly dripping over root zone. Overhead watering may cause flowers to tip or fade; some species are more subject to disease if showered from above.
Planning ahead? For closely spaced beds, choose drip-emitter lines; for widely spaced plants, use individual drip-emitters.
Build basins of soil around large, shrubby plants.
Planning ahead? Use in-ground sprinklers; install stationary risers (pop-up types) for plantings more than 1 foot tall, and low-output sprinklers on a slope. Or install a drip-irrigation system for shrubby ground covers.
TREES AND SHRUBS
Build basins of soil around shrubs.
Attach a deep-root irrigator to the end of a hose and inject water into the soil near a tree’s roots.
Soaker hoses work well for occasional deep watering of established trees. Lay them on flat ground; wrap them around the tree several times–starting a few feet out from the trunk and ending just beyond the drip line.
Planning ahead? Low-volume systems with drip-emitters or micro-sprinklers (miniature sprayers) are most efficient, especially on slopes.
Build basins of soil around the plants to direct hose water to roots.
On level ground, snake soaker hoses around plants.
Planning ahead? Install in-ground sprinklers with flat-head sprayers (on short risers, these send the spray out straight, rather than up, where it can wet the foliage); run them early so leaves will dry by midday. Or, for closely spaced bushes, install a drip-irrigation system with a drip-emitter line and individual drip-emitters.
NATIVES AND UNESTABLISHED DROUGHT-ADAPTED PLANTS
Warm, moist soils can be lethal to many native plants and to those of Mediterranean origins, especially in poorly drained soil.
If plantings are less than a year old, use ooze-type soaker hoses at low pressure, very early or late in the day when soil is cool.
Planning ahead? Use low-flow drip-irrigation with a manual shutoff valve for the first year or so, until plants are established. After that, natives and drought-adapted plants need little to no water beyond rainfall.
Hand-water gently, using a hose fitted with a wide nozzle.
Submerse hanging baskets and small pots for half an hour in tubs of water to saturate soil.
Install drip tubing to water pots for two to five minutes, several times a day. Simple drip-irrigation kits for container plantings are sold at garden centers and nurseries.