The basics of watering plants

The amount of water a plant needs depends on the type of plant, soil, location and the weather including temperature, humidity, and wind. It is easy to see why plants can be over-watered or under-watered.

Some methods, including hand watering and some sprinklers, make water puddles or run off long before the soil receives as much water as it needs. Many gardeners stop watering when the soil surface becomes soggy or when water starts to puddle or run off. This practice only wets the top few inches of soil. Because the rate of water absorption into the soil is slow, it may take several hours or days to wet some types of soil 3 – 4 inches deep. To water deeply and prevent run off, apply water at the same rate at which it enters the soil. If your irrigation system cannot be adjusted to apply water slowly, water until run off begins, stop watering for about an hour, then water again, until the soil has been wetted as deeply as necessary.

Each time you water, apply enough to wet the soil to the bottom of the root zone. Water is measured in inches. If a tin can is placed on a lawn when the sprinklers are turned on, the soil receives an inch of water when the water in the container is one inch deep.

water lilies

There are two primary variables involved in watering plants: how much and when. There are many ways of knowing when to water, some of which are very sophisticated. Here is one of the simplest and easiest to learn.

First, dig a hole into the root zone of the plant, from 2 – 6 inches deep. In loose soil you can dig a hole with your finger; otherwise, use a trowel or a shovel. Second, feel the soil in the hole. Dig a new hole each time you check. When the soil reaches a certain level of dryness, it is time to water again.

When watering container plants, apply enough water so that some drains from the bottom. Drainage water should flow freely away from the container so that water does not collect around the base. If the container is sitting in a saucer, wait for all the water to drain through (10 – 15 minutes), and then empty the water from the saucer. Sometimes the drainage holes become blocked and water accumulates inside the container rather than flowing out. Make sure the container drains after watering. If not, poke a stick in the drainage hole to loosen compacted soil. Water again when the soil just below the surface is barely moist.

In large containers (10 – 12 inches or more), water when the soil 1 -2 inches below the surface is barely moist. Plants in containers without drainage holes are difficult to water properly. Water accumulates in the bottom of the container, causing root rot. If the soil in the container becomes too dry, it may be difficult to re-wet. Instead of penetrating the soil, the water runs down inside the edge of the container and immediately drains out the bottom. To wet the soil, soak the container in a tub or sink full of water for a few hours. The rim of the container should be submerged.

Aquatic plants are extremely beneficial as far as the health of your pond or aquarium is concerned. They are also an undervalued part of the freshwater eco-systems. There are many people who do not like these plants in their fishing holes but little do they know that the aquatic plants play a very important role in a water body. A few of its advantages have been listed below.

Habitat: Aquatic plants provide space for small aquatic, crustaceans and snails to live in. These insects are in turn eaten by fish and waterfowl. Therefore it enables the food-chain to keep going.

Food: The aquatic plants are food for many animals and birds like ducks and geese. They usually feed on the seeds and tubers of plants. In the past, even humans have made use of these aquatic plants as food. Edible roots, shoots and even pollen have been utilised for the making of biscuits. Native Americans have a delicacy called “duck-potatoes” which are the edible tubers of Arrowheads.

water lily

The roots as well as the shoots of the aquatic plants can sometimes be of medicinal value and can sometimes be used for salads and garnishes.

Cover: Amphibians and young fish use the aquatic plants to hide from the predator fishes. They provide them enough foliage to keep themselves under cover so that they do not become feed for the larger fish. These plants are ideal for baby fish nurseries because apart from providing them with a protective cover, they also are a source of food for them.

Nutrient Cycling: Water plants have a vital part to play in the complex chemical cycling in a water body. They influence the oxygen content in the water. They have recently been in the news for their ability to soak up pollutants from water that is highly contaminated. They utilize the nutrients for the improvement of water clarity. Scientists are trying to develop ways and means through which they can be used as indicators of water quality.

Control of Erosion: Emergent plants protect the shorelines from erosion. They also help to stabilize the sediment which can increase the clarity of the water.

Floating water plants are those that are not anchored by roots, although some do produce a few straggly roots that simply dangle in the water.

These plants tend to die down during late autumn, surviving the winter as dormant ‘buds’, resting in the mud at the bottom of the pond. In spring, when the weather warms, they burst into life again.

Some floating plants increase their size and number rapidly and can cause overcrowding in the pond. It is for this reason that there is a restriction in the sale of such plants in some warmer climates, including some of the southern states of the USA, where the winters offer less of a check to their growth. Let’s consider some of the best floating plants:

aquatic plants

- Common duckweed (Lemna minor)
The origin of the common name is, to say the least, hazy, although ducks on larger ponds and lakes will certainly nuzzle around looking for small creatures hiding in it. Some fish eat it, and they lurk under the shade it affords. The form that is generally found in garden ponds is Lemna minor and, if you introduce it to your pond – either accidentally or on purpose – the pond will soon be covered with a pale lime-green ‘carpet’. Don’t walk on it though, like a child did when I was visiting Wisley gardens in the 1970s. Fortunately the pond was very shallow, but the youngster had a nasty shock, and so did his parents.

FLOWERS
These appear in summer, and are tiny, grey-white and wholly insignificant.

LEAVES
Minute almost translucent, deciduous fronds in various shapes, but mostly oval. Thousands of them abut each other to form a dense carpet over the surface of the water. Each individual frond usually produces a single, dangling root.

CULTIVATION
One doesn’t really ‘cultivate’ duckweed -it just happens! Planting comprises simply dropping several leaves with roots into the pond, generally in spring. It grows best in still, or nearly still water, and in either full sun or light shade. Duckweed is left to its own devices. All you need to do is use a net to thin it out occasionally to prevent it from covering and choking the whole pond.

HARDINESS
Very hardy, tolerating temperatures as low as -20°C. Duckweed survives in winter as dormant buds on the bottom of the pond.

PROPAGATION
Again, one doesn’t really ‘propagate’ duckweed. Just redistribute some of the fronds to a different pond.

ORIGINS
A one-species plant, originally from the Atlantic side of North America.

HEIGHT
None – to speak of.

SPREAD
A couple of individual fronds can increase and cover up to lm2 (9 sq ft) in a year, but thereafter rapid covering of ponds can take place.
water plants

MINIMUM WATER DEPTH
15cm (6in).

MINIMUM POND SIZE
Small – up to about 2m (18sqft).

ALTERNATIVE
Perhaps the best form to choose is the ivy-leaved duckweed (Lemna trisulca). This is less invasive than the common kind and produces a mass of star-shaped leaves, frequently floating just beneath the surface. Lemna gibba, often referred to as the ‘thick’ or ‘gibbous’ duckweed, has rounded, swollen leaves and is particularly invasive. Lemna polyrhiza (also known as Spirodela polyrhiza, and commonly referred to as ‘great’ duckweed) has larger, rounder leaves than the normal kinds, and each has a small ‘tuft’ of roots attached. Very invasive.

EXPERT TIP
Most gardening experts are asked how to get rid off duckweed, rather than how to grow it. Be warned: if you don’t want it, it is important to check carefully each new water plant for the presence of duckweed before it is introduced to the pond.