What to Water
You do not need to water everything in the garden, even during hot
spells. For example, long-established trees, shrubs, roses, climbers,
and hardy perennials with extensive root systems can withstand periods
of drought. Established lawns, too, can usually go without extra
watering; even brown, parched grass will normally green up again when
Certain plants, however, might need additional watering:
New plants have small, immature root systems that are not yet able to
reach water held deep in the soil. Watering after planting—even if the
soil does not seem dry—not only keeps the roots moist but also settles
the soil around them.
- Wall-trained plants can be in a “rain shadow,” sheltered from rain by
the wall and house eaves. Consequently, the soil around their roots is
very dry. If you plant about 18 in (45 cm) away from a wall or fence,
the soil will hold more moisture. Mulch plants deeply in spring when the
soil is moist to keep it that way.
- Newly germinated seeds and seedlings will die if the roots dry out.
Stand pots or trays in water, so that they can take up moisture from
below, and then remove them when the top of the soil is damp. This
avoids water on the leaves, which increases a seedling’s susceptibility
to fungal diseases, such as damping off.
Conifers can suffer and may die in hot weather without enough water;
if the foliage is badly scorched, it may not regrow. Some, such as
juniper and pine, are more tolerant of dry soil, and are good choices
for warm, sunny gardens or sandy soil.
- New lawns have to be watered until they are well established.
Expensive new sod will curl up and die if subjected to drought.
Established utility lawns containing ryegrass can do without water. They
may turn brown but will green up again after rain.
- Fruit and vegetable crops need water most when they are flowering and
developing their fruits or other edible parts. If they run dry at these
times, cropping is badly affected. Many leafy vegetables wilt or go to
seed in hot, dry conditions.
- Shallow-rooting rhododendrons fold down their leaves when short of
water in hot, dry periods. Flower bud formation is affected, and plants
will brown and die if not watered. They are not a good choice for hot
spots or sandy, free-draining soils.
- Plants in containers need plenty of water because they are growing in a
limited volume of soil, which rapidly dries out. In hot, dry, and windy
weather, check them daily, and twice a day in exceptionally hot summer
weather or if the pots are small.
When planning or adding to plantings, choose plants that match your soil conditions. Drought-resistant plants, such as sedums and lavender, need little or no additional watering; others, such as conifers, will become scorched and remain unsightly forever if water is in short supply. Create a shallow depression around the plant after planting. Water will then be retained over the area of the roots while it soaks into the soil.
How to Water
Water early in the morning or in the evening, when cool conditions reduce evaporation, and plants take up less water than at warmer times of the day. Under a hot midday sun, water droplets on leaves will act as miniature magnifying glasses and may scorch them. Aim to water plants that are susceptible to slug and snail damage in the morning, as extra moisture in the evening encourages these nocturnal pests. When watering, a weekly soaking is better than a daily dribble. Light watering does not penetrate far and encourages the roots to grow up to the surface to reach the moisture—and, of course, they are then even more vulnerable to drought.