Plants must have the right amount of water to grow properly. For plants to take up nutrients from the soil the nutrients must be dissolved in the water first. Plants also need water to keep cool and allow their internal processes to take place.
Most plants- especially tropical plants- grow best in humid conditions. Winds, draughts and dry atmosphere can cause plants to be unable to absorb enough water through their roots to replace what is lost through transportation. If plants do not get enough water they wilt, drop their leaves and eventually die. Cacti and other succulent plants are adapted to dry conditions. Ferns are very susceptible to dry conditions.
Too much water results in root damage owing to a lack of oxygen in the soil. Prolong waterlogging results in poor growth and eventually death.
During germination it is important that the seeds are kept moist. For this reason care is needed when preparing seedbeds to ensure that clods of soil are broken down and the seeds are surrounded by moist soil. A fine sprayer should be used for watering pots and beds where seeds are planted. This avoids soil being moved and seeds uncovered.
When seedlings are transplanted, you must be careful not to damage their root system or let them dry out. Thorough watering straight after transplanting makes it easier for the plants to obtain water and settles the soil around the roots.
The pH (level of acidity or alkalinity) of the soil or solution in which plants are grown has an affect on their growth. Usually the closer to neutral, the better. However, some plants prefer a slightly acid and others slightly alkaline conditions.