Horticulture Principles and Practices

370 Chapter 11 Growing Houseplants
instruments, although one of them is not soil surface dryness. Most plants are overwatered
because growers look at the soil surface without knowing what is going on beneath
it and decide that watering is required. It is best to stick a finger into the potting medium
to a depth of about 1 inch or more (or use a piece of stick) to determine the stickiness or
moisture level of the soil.
11.3.9 HOW MUCH WATER TO PROVIDE
Plants have different water needs. It is a waste of resources and a danger to plants to supply
more water than is needed. For a particular plant, the amounts applied may be varied
depending on the growth phase. In terms of quantity applied, plants may be watered in
these general ways:
1. Plentifully (or liberally). In watering liberally or plentifully, the potting medium is
kept constantly moist. When water is needed, plants may be drenched with water
until the medium can hold no more. At this stage, excess water collects in the drip
tray or saucer. This excess water should be discarded. Drenching can be done from
the top or by placing the pot in a container of water and allowing it to soak up
water until it can take in no more. The pot is then removed from the water.
2. Moderately. When water is applied in moderate amounts, only a small amount of
excess water drains into the saucer. If a grower is using the soaking method, only
a little water should be added to the container at a time. Water is added continually
until the surface of the soil is moist. The plant is watered again when the soil
feels slightly dry.
3. Sparingly. Watering sparingly keeps the growing medium only partially moist. Water
never drains out of the pot. The plant is rewatered when most of the soil is dry.
Caution: These three general watering regimes are not alternatives. The method chosen
for a situation depends on the specific needs of the plant, the conditions under which it
is growing, and its growth phase.
11.3.10 ROLE OF PLANT GROWTH CYCLE
IN WATER NEEDS
The plant growth cycle is often overlooked in the management of houseplants.
Deciduous plants have a visible and predictable alteration between active growth (spring
to fall) and rest period (winter), because they shed their leaves in the cold season. Without
leaves, it is not difficult to guess that the plant does not need as much nutrition (water
and minerals) as it does when it has leaves. Many bulbs and corms also have periods of
rest during which their aboveground portions die back. However, many plants also have
rest periods in their biological clocks that are less obvious. These species do not exhibit
any dramatic signals to prompt the grower to make the necessary adjustments in management
practices. These evergreen species, like most foliage houseplants, retain their
foliage year-round. Some horticulturalists recommend that many indoor plants be forced
to rest in winter when daylight is reduced. Induced resting may be accomplished by
reducing the amount of water supplied and discontinuing fertilizer application. The best
approach, however, is to consult the growing instructions supplied with plants or seeds
purchased from a nursery.
11.3.11 METHODS OF APPLYING WATER
Water may be applied to plants by using any convenient container such as a cup.
However, it is advisable and most convenient to use a watering can to water houseplants.
Very inexpensive, lightweight plastic watering cans with long and thin spouts may be
purchased from supermarkets. A long spout enables watering without spilling and
splashing onto leaves. It also increases the maneuverability of the operator so that plants
positioned in hard-to-reach places are readily watered. For homes with glasshouses,