When moving plants from indoors to outdoors, the plants need the opportunity to become accustomed to the outdoor temperatures and elements. Prior to transplanting into your outdoor garden, give the plants a chance to experience the outdoors.

Hot beds are used for starting seedlings.  A hot bed will have a heat source to start plants before the last frost.  It is like a "miniature" greenhouse.

A more proactive approach to composting, producing finished compost faster.  Hot composting involves mixing, aerating and lightly watering the compost pile as well as layering different types of materials.

Decomposed organic matter.  Humus can also refer to finished compost, which is dark and crumbly.

The process of growing plants with water and nutrient solutions and without soil is called hydroponics.   Hydroponics is more involved than growing with soil as there is more maintenance involved and the plants are typically grown in a greenhouse or under artificial light.