Plant Growing Needs

Plant growing needs – what needs a plant to grow? Certain factors in the environment (external factors) and within the plants (internal factors) influence the plant growth process and performance. These factors can enhance, reduce or limit plant growth development.

The plants will flourish when all these factors favour growth. If you like how they grow read my article "how do plants grow?".

Plant growing needs:

Plant Growing Needs: External Factors

Light

Sunlight provides energy that it taken up through the plant’s leaves. This energy fuels the chemical process of photosynthesis where the plant converts water and carbon dioxide to carbohydrates (plant food).

Light affects also another reverse chemical process: plant respiration where carbohydrates are converted into energy and then oxygen is released through the plants leaves as a by-product.

Carbon Dioxide

We all know that animals are breathing. Plants breath as well! Yet, while animals inhale oxygen and exhale carbon dioxide, plants do the reverse thing: they breathe carbon dioxide in and oxygen out. They breathe through stomates (stomata), which are placed on the leaves. Water acts as a solvent for the two gases and transports them through the plant.

Water

Water is essential because it moistures the soil and dissolves important nutrients that the plant needs in order to grow. This nutrient-enriched water is then taken up through the roots hairs and transported through the plant.

Water is also needed to transport carbon dioxide and oxygen through the plant.

Nutrients

A plant needs essential nutrients in order to grow. A nutrient that limits plant growth is considered to be essential. When plant growth is limited the plant life cycle cannot be completed.

There are three non-mineral nutrients that are available in the air and in the water: hydrogen (H), oxygen (O) and carbon (C). The plant needs these nutrients together with sunlight to carry out photosynthesis.

Mineral nutrients occur in the soil. They are called macronutrients and micronutrients. Macronutrients are used in larger quantities than the micronutrients. That is why the micronutrients are also called trace elements.

Three factors influence the plant nutrient availability and uptake from the soil:

• Availability of water
• Soil texture
• Soil pH

Water in the soil acts as a solvent. Only dissolved nutrients can be absorbed through the root.

The soil texture is important because it influence how well nutrients are retained in the soil. For instance, nutrients are easily flushed away in sandy soil and they soil becomes nutrient deficient. Yet, soil that is rich in clay can retain the nutrients much better because it has a much firmer texture than sand.

Fertilizer can be added when there the soil is short of certain nutrients to provide enough nutrients for plant growth.

The pH of the soil acts on the availability of macro- and micronutrients differently:

• Macronutrients are more likely less available in soils with low pH
• Micronutrients are more likely less available in soils with high pH

Different plants have different pH preferences but most grow best in a pH range of 5 – 7.

Temperature

Temperature is also one of the crucial plant growing needs. It has an effect on:

• Photosynthesis
• Respiration
• Transpiration
• Germination
• Flowering
• Dormancy
• Energy production
• Sugar storage

Photosynthesis, plant respiration and plant transpiration increases with increasing temperature. Yet, when a certain point is reached, the transpiration rate exceeds the photosynthesis rate. This has a detrimental effect on the plants growth.

The plant growth stages of germination, flowering and dormancy are induced by temperature changes. An increase in temperature will trigger germination and flowering.

A temperature decrease causes the plants to enter dormancy. On the other hand, rising temperature will break dormancy and the plant continues to grow and reproduce.

Furthermore, the energy use is reduced and sugar storage is increased in periods of low temperature. That is why grapes are purposely exposed to cool, fall nights to increase their sweetness.

Temperature also influences the humidity (see below). The warmer it is the more water vapour is held in the air.

Humidity

Humidity refers to the amount of water vapour in the air. It is important to understand that water vapour is moving from areas of high humidity to areas of low humidity. The bigger the difference in humidity the faster the water is moving. This process has an effect on the plant transpiration rate.

Humidity is much higher between the leaf cells (actually the relative humidity is at 100 %). Therefore, water vapour rushes out the leaf as soon a stoma opens and forms a small droplet of water, which covers the stoma. This prevents more water vapour to move out of the plant.

Yet, on windy days these protective water droplets are constantly blown away and as a consequence, the plant has to increase its transpiration rates. This is the reason why plants rapidly wilt on windy, hot and dry summer days.

Gravity

Plants need gravity for growth orientation. Their roots grow into the earth in the same direction as the gravitational pull. This is called positive gravitropism.

The other parts of the earth grow towards the sky against the direction of the gravitational pull. This is called negative gravitropism.

Plant Growing Needs: Internal Factors

Internal plant growing needs are as important as the external ones!

Plant hormones

Plant hormones are chemicals that are produced within the plants. These chemicals have many various effects on the plant growth and formation.

The five most important and best-researched classes of plant hormones are:

• Auxins
• Abscidic acid
• Cytokines
• Ethylene
• Gibberrelin

Return from Plant Growing Needs to Plant Biology
Return from Plant Growing Needs to the Plant and Flower Guide

---

Copyright © 2009-2012 plant-and-flower-guide

---