Glossary of gardening terms - A:

Acid/alkaline soils
Describes the concentration of hydrogen ions in the soil.

Acid soil
A soil with a pH lower than 7.0 is an acid soil. A soil pH higher than 7.0 is alkaline. Basically, pH is a measure of the amount of lime (calcium) contained in your soil.

Alkaline soil
Alkaline soils are common in light rainfall areas. Soil is called Alkaline when the ph level is more than 7.0, the higher the number the more alkaline the soil is.

Annual
Annuals are among the most adaptable of garden plants, demanding average light, sufficient water, and reasonably fertile soil. They are called annuals because they complete their life cycle in one growing season. The seed germinates in the spring, the plant grows and flowers, produces seed and dies at the end of the season.