Plants grow in an extreme variety of climates from Cacti in the desert to Pines in the Arctic circle. However, whatever kind of plant, they all share the same basic scientific criteria for growing.

The essential things a plants needs in order to grow is:

• Water
• Sunlight (energy)
• Carbon dioxide
• Food – Nitrogen, Potassium and Phosphorus and Trace Minerals
• Warmth

1. Water (H2O) Water is indispensable for plants, and is nearly always taken through the roots. Main roots have many much smaller root hairs.

• The water passes through the epidermis layer on the outside.
• It then passes through the vascular rays until it reaches the centre of the root, the stele.
• It is here in the centre of the root, that the veins or (xylem) carry the water up the plant to where it is needed.

2. Food. Plants need a variety of minerals which they take in soluble water. Note if the plant is dry and unable to take water, it is also unable to take food.

The main nutrition for plants is:

• Nitrogen (N) Nitrogen is needed for growth
• Phosphorous (P) – phosphorous is needed for root growth
• Potassium (K) – Potassium is used for fruit and flower formation

Other Nutrients. As well as the big three, plants also take small amounts of macro nutrients such as calcium (Ca), sulphur (S), magnesium (Mg).

Micronutrients. Plants take a variety of ‘micronutrients’ or trace minerals: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni), selenium (Se), and sodium (Na).

3. Photosynthesis (“light” and “putting together”)

As well as soluble minerals from the ground, plants also require the energy of the sun to grow.

Photosyntheses occurs in Chloroplasts which have cholorphyll in them.
Chlorophyll absorbs sunlight and uses the energy of the sun to combine carbon dioxide and  water to make sugar and oxygen. This is why plants and trees are often referred to as the ‘world’s lungs’ as they absorb carbon dioxide and produce oxygen.

From sugar, green plants can make fats and proteins needed by the plant

At time, without light, plants cannot make food so they shut down and effectively sleep.

Note, the living cells of plants also take in oxygen. During the day, the effects of photosynthesis means they produce much more oxygen than they use, but at night, they may actually take in more oxygen than they exhale.

4. Warmth

The tolerance of plants to temperature varies enormously. However, generally, plants need temperatures of, at least, above 5 degrees to be able to grow . However many plants can survive at below freezing temperatures for a considerable time.

Related

• Best Plant Food
• Helping plants grow – BBC interactive for children
• How Plants grow – Library think quest