Plants need three things to grow and thrive: water, light and nutrients. When plants fail to receive one of these three, the plant will fail to thrive. Conversely, when a plant receives too many of these three things, it can also die. But a plant that receives an optimal balance of water, light and nutrients will thrive and produce abundantly.
Seeds are the embryo state of plants. If you were to split a seed open, you would find a tiny plant and a large mass of nutrient that powers the plant for its initial push through the dirt to find sunlight. Once plants sprout, they require a number of nutrients found in soil to survive. The nutrients that they need the most of include nitrogen, phosphorous and potassium. As plants grow, they pull these nutrients from the soil. In order for plants to thrive in nutrient-poor soil, many farmers add nitrogen, phosphorous and potassium back to the soil in the form of fertilizer.
In the absence of water, a seed will not germinate. The first step in the process of germination is the absorption of water. Absorbed water activates an enzyme that begins cellular reproduction that leads to a plant breaking free of the seed and sprouting. Once germination begins, a dry period can kill an embryo. As a plant grows, its dependence on water is as strong as an animal's dependence on water. Like mammals, plants are primarily made up of water. About 95 percent of a tomato is water. In addition, good soil moisture helps to improve nutrient uptake, which will also help a plant to thrive.
The initial burst of seed energy during germination is involved in sending shoots upward into the light. Light is one of the primary ingredients required for photosynthesis, the means through which a plant creates sugar for food and energy. Plants that require more light develop structures for absorbing more light, such as leaves on a tree. The three light factors that affect plant growth are quality, quantity and duration. Light quantity varies by seasons, with more during summer. This is why in many parts of the country, plants grow best during summer months. Quality refers to the color intensity of light. Sunlight contains all the wavelengths, which is why seeds and plants placed outdoors thrive. Blue and red light have the greatest effect on plant growth. Blue encourages growth, while red encourages flowering. This is why indoor seedlings grow well under fluorescent lights that have a strong blue wavelength. Duration of light controls flowering of plants. This is why all plants grown indoors under lights require a nightly resting period in order to stimulate flower or fruit production.