Plant growth is caused by water that is absorbed by the plant's roots and sunlight that spurs photosynthesis, which is the process of creating food for the plant. Plants also need space, time, clean air, healthy soil and nutrients to grow. The main ingredients that plants need are phosphorous, nitrogen and potassium.
Most plants need moist soil to grow well. The moisture and nutrients travel from the roots to the leaves. Plants are usually fed nutrients through fertilizer. Nitrogen gives plants the green coloring in the foliage, and phosphorus fosters durable roots and larger flowers. Potassium keeps diseases at bay.
The soil contains essential nutrients that plants need, and soil holds the plant and roots in place. Plants also need room to grow above and below ground. Plants that are crowded together are more susceptible to disease because of limited airflow.
Clean air is essential to plants because dirty air clogs the ability of plants to absorb carbon dioxide and spur photosynthesis. Gas, smoke and other irritants are a few things that hamper a plant's growth rate.
Temperature is just as important as light, since excessively hot or cold weather can have a negative impact on plant growth. Plants generally prefer warm daytime temperatures and mildly cold nights to thrive. Plants also need a certain time frame to grow. Some plants may take months, days or years to produce foliage or fruit.