How Plants Grow

The majority of us take the growth of plants for granted — leaving it all up to Nature and what she does best. Yet if we truly care about our plants, and want to ensure that they thrive, then it is vital that we understand the basic facts of how plants function.

The process is complex and involves a number of individual processes that are all interlocked and dependent upon one another.

Photosynthesis

This is the way that plants manufacture food. The process uses the raw ingredients water, carbon dioxide and sunlight to make carbohydrates essential for growth.

Water, containing dissolved minerals present in soil and compost, is absorbed by the plant’s roots and transported through stems to the leaves.How Plants Grow

Carbon dioxide, present in air, is taken into a plant’s leaves through small pores called stomata.

Sunlight is the source of energy that activates the process of photosynthesis, which can take place only in parts of a plant containing the green pigment, chlorophyll. Sunlight activates chlorophyll to provide chemical energy that combines water and carbon dioxide, creating complex compounds such as starch. The process involves the release of oxygen from water (which is composed of oxygen and hydrogen) into the atmosphere.

Photosynthesis occurs only after chlorophyll has been activated by sunlight, and therefore it cannot normally happen during darkness. However, chlorophyll activated late in the evening will continue the process of photosynthesis until its energy has been exhausted.

Respiration

This vital breathing process is common to both plants and animals, and occurs all the time. With plants, oxygen is taken from the atmosphere, through the small pores in leaves, and carbon dioxide given off. This is a reversal of the flow of gases during photosynthesis.

Compounds within a plant are broken down to release energy.

Usually the higher the temperature, the greater the rate of respiration and the faster the expenditure of the plant’s energy. And because plants do not photosynthesize at night (and are therefore not creating growth), high night temperatures can soon exhaust a plant.

Preferably, plants need warm temperatures during the day (so that they can photosynthesize and grow) and cool conditions at night so that the energy created during the day is not wasted by unnecessary fast respiration.

Transpiration

This is when water vapour is given off through the pores in leaf surfaces. Water is an essential part of the process of photosynthesis. It also, during the transpiration process, serves as a coolant for the plant.

Water absorbed by the roots passes through stems until it reaches the surfaces of leaves. During its travels, and especially in large-surfaced leaves, the water warms up. The action of water being transpired from leaves draws in cool water through the roots that then reduces the temperature of the plant. If plants were not cooled, they would soon shrivel, especially during hot weather.

Transpiration works in other important ways — helping water and food to be circulated through the plant. Water absorbed by the roots for use in photosynthesis and for transpiration travels upwards through xylem cells, while food materials created through photosynthesis are moved to parts where growth is needed — or food is to be stored — through phloem cells.

Water also plays a vital role in keeping a plant rigid, and standing upright.

Plants are adaptable, and they can thrive in steamy jungles, in soil that is thickly covered with ice, in ponds in deserts, in salt water, even in barren land. There are few places on Earth that have not been colonized by plants. Some of these plants can be kept as house plants, providing you give theft) the right conditions.

Cacti and succulents: These have adapted themselves to grow in places where there is little rainfall — hence they need less water than other plants. They have thickened surfaces to prevent moisture loss, and tissue that can store water.

Insectivorous plants: These live in places where their roots cannot obtain sufficient nutrients, so they have developed parts to trap and digest insects. The Venus Fly Trap and the Pitcher Plant are good examples.

Epiphytes: These are plants that grow above the ground, often on branches of trees. They use their host for support, not food.

Do’s and Don’ts

DO

  • Keep plants at the recommended temperature. Plants grown indoors come from all over the world and need individual attention.
  • Feed your plants regularly, but never during their dormant season or when they are not growing rapidly — usually during winter.
  • Repot plants as soon as the compost is full of roots. This is usually best done in spring.
  • Give plants the recommended amount of light — some plants thrive in strong sunlight, while others are best in slight or full shade.

DON’T

  • Keep the compost continuously saturated. Thoroughly soak the compost first, and then allow it to become nearly dry before adding more water.
  • Give your plants widely varying temperatures. Changes of a few degrees between night and day are desirable, but if they differ by 10°C (20°F) the plant will suffer.
  • Position your plants in draughts.
  • Splash water over leaves and flowers, especially during winter.

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