- Aerate
- Mechanically loosen soil to allow for better air permeability and water penetration.
- Alkaline Soil
- Soil having a pH above seven.
- Allelopathic
- The ability of certain plants to prevent the growth of other plants.
- Alpine
- A plant from mountainous, high-altitude regions.
- Anchor Root
- A large root serving mainly to hold a plant in place in the soil.
- Annual
- A plant that completes its life cycle within one growing season.
- Amendment
- The addition of material, such as compost, into the soil to improve its texture.
- Anaerobic
- Describes organisms living or occurring when oxygen is absent. Usually term used when talking about compost heaps.
- Aphids
- Tiny, oval insects that are found in clusters on the young shoots, buds and leaves of a plant. One of the most prevalent of garden insects. They usually congregate on the undersides of plants' foliage and suck the nourishment from the stems and leaves.
- Aquatic
- Plant which grows partially or completely in water.
