Royal Caledonian Horticultural Society
Plant and Grow - Gardening for Children
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Other interesting things to know about gardening

temperature for plants



Climate and Temperature for Plants

Plants will only grow in a certain temperature range. Some plants, like grass will grow throughout the range but others need a temperature that is not too hot or too cold.

Temp. (Degree Cent.)
Too Cold                                 
Too Hot
      5____(10____15____25)____30
                                      

          / Ideal temperature range\


The Plant and how it Works

Each part of a plant has an important function.

Flowers

Flowers can look wonderful but their job is to produce seeds that reproduce the plant to ensure its survival. If you look closely at a flower it should be quite easy to identify all the parts. The flower is divided into male and female sections, one for producing pollen, the stamen, and one for receiving pollen to fertilise the seeds, the carpel. See the picture at the top of the page.

photosynthesis

Leaves and the Process of Photosynthesis

The green leaves of a plant are important for photosynthesis; this is the process by which a plant manufactures sugars and proteins for its natural growth. Plants require sunlight energy in order to build up their complex organic compounds - sugars, starch and proteins - from the simpler inorganic substances they absorb through their roots. The process of photosynthesis, is not only dependent on sunlight. It also requires the presence of green pigment in plant leaves and a supply of water and carbon dioxide within the plant before it can take place. Plants that do not receive sufficient sunlight do not grow well and turn pale green or yellow in colour. This can be seen on a lawn that has been covered by a play-mat or other objects for a few days. When they are removed a greenish yellow shape marks the area that the items covered. Plants do not grow well in areas shaded by hedges, trees or buildings. Not only do they get poor sunlight but the competition for water and nutrients will also affect them.

The Stem

The stem is for supporting the plant and keeping it upright. It also contains a system of microscopic tubes that move water, nutrients, proteins and sugars around the plant. This process is known as transpiration (water movement) and translocation (movement of proteins and sugars).

Transpiration

Water gives a plant turgid support and helps to keep it standing upright. As water evaporates from the surface of the plants leaves, the action pulls more water through the plant and is known as transpiration. The process of evaporation can be seen on a hot day where if a plant does not have an adequate supply of water it will wilt and become floppy. Pot plants and plants in hanging baskets will wilt if they are not watered regularly.

Translocation

The internal structure of a plant, the plant cells, allow the movement of water and nutrients in one direction and the flow of sugars and proteins in the other. This process is known as translocation.

Roots

Roots hold a plant in the soil and absorb water and nutrients through their microscopic root hairs. A good root system is most important for a healthy growth. Damaged or poorly developed roots cannot absorb adequate water and nutrients for normal plant growth. The roots of a plant will rot and die in poorly drained cold, wet soil. Insect and fungal infestations can also destroy a plant's root system. The two main types of root system are tap roots and fibrous roots.

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Worms and Soil Organisms

There are many insects and organisms (small living things) that live in soil. They all have a purpose and there is a close balance between those that ‘are good’ and those which are ‘harmful’. Occasionally this balance is altered because conditions change and certain types of organism can become more powerful and start attacking and killing plants.

Earthworms are entirely good (beneficial) animals performing important functions in the soil that increase its fertility and improve its structure and aeration. They are valuable in treating waste, combating pollution and generally help to tidy the garden of leaves and other rotting vegetation. Worms take plant material and leaves into the soil where it rots and is eaten to form humus (humus contains nutrients). This aids soil structure. The burrows formed by worms aerate and break-up the soil helping drainage and creating space for plant root growth.

The 19th century scientist, Charles Darwin studied earthworms and found that they are tremendous earth movers. Over a period of 30 years he noticed that a stepping-stones path he built across his lawn had been completely covered and had disappeared from sight. He observed that this was the action of earthworms producing ‘casts’ (small piles of soil) all over the lawn and path area. Earthworms belong to a group of invertebrate animals that have segmented bodies. There are 28 British species of earth worm and it is estimated that there are 7.5 million of them per hectare. Garden compost contains the small, red Brandling worms.

Garden Compost - Recycled Rubbish

When plants die they decompose which means they rot and disappear. Unwanted plant material can be collected and put into a pile to form a compost heap. With the help of bacteria, insects and worms, the plants gradually rot and start to turn into compost. Composting is a natural way to recycle unwanted plant and other organic waste into a soil-like substance that is also an excellent plant food. It is a good soil improver and the best way of adding fertility. When compost is mixed with a heavy soil the result becomes easier to work and will also aid moisture retention when added to sandy soils.

the compost heap

How to make compost

Just about anything that will rot down can make compost

Plant waste - green plants, roots, vegetable waste, garden rubbish

Warmth - cover the heap and keep it warm

Air - turn the compost to let in air. This helps rubbish to decompose

Moisture – worms and living things need moisture (not too wet)

Soil-organisms - add small amounts of garden soil to aid composting

House-hold waste - egg shells, tea bags, vegetable and soft fruit waste, newspapers and organic things that will rot and decompose.

Never Compost - meat, fat, cooking oil, dairy products, synthetic fibres (nylon clothing), citrus fruit, wood or woody plants: (meat, dairy products, bread, cakes and biscuits will attract rats to a compost heap). Perennial weeds should only be composted if the heap can produce enough heat to kill them. Regularly turn the composting material.

Time - allow time for the organic materials to rot down.

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Plant Food – Nutrients (Fertilizer)

All plants must have water, air, nutrients and warmth to grow. The best way to supply the food that plants need is to give them a good helping of garden compost or farm manure. This is sometimes called ‘organic gardening’.

The Nutrients that Plants Need - Minerals

Plants need minerals to grow. They are divided into two groups - Major Minerals and Trace Elements. There are three minerals that must be supplied for plants to grow well. In order of importance they are:

plant nutrients

1. Nitrogen 'N' - needed for proteins, chlorophyll and genetic material

2. Phosphorus 'P' - for proteins, respiration, cell division and membranes.

3. Potassium 'K' - needed to balance water in cells.

There are also three other important minerals that plants need in small quantities -

Calcium 'Ca' - for cell walls and membranes

Magnesium 'Mg' - needed for chlorophyll

Sulphur 'S' - needed for proteins

Trace Elements – many other minerals that are required in very small amounts.

Mineral availability is dependent on the amount of acid in the soil – the soil pH. If a soil is too acid or too alkaline then certain minerals and trace elements become ‘locked-up’ and will not be available to growing plants. Acid soils can be improved by adding chalk - lime (Calcium). The three most important minerals are N, P and K.

Artificial (Chemically made) Fertilizer for the Garden

Gardeners can now buy balanced fertilizers to help plants grow and thrive. These can be in granular or liquid form. Modern fertilizers are scientifically formulated and contain the correct balance of N. P and K minerals for plant growth. Too much of one mineral can harm plants. For example large quantities of nitrogen will give lush green growth but the plants will become weak and floppy and are susceptible to attack by pests and diseases. Large quantities of chemical fertilizer will kill plants. Slow acting fertilizers have been developed to release nutrients over a period of 6 to 12 weeks. When mixed with compost, these products are ideal for pot-plants, containers and hanging baskets.


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