A garden frame is a bottomless box with a transparent top that is used to provide favorable conditions for the plant's growth and to cover them during harsh weather. The top is made of plastic or glass set in a wooden or metal frame. Their are unheated and heated frames and they are both good for raising seedlings ahead of the outdoor season and for growing early crops of Lettuce, Cauliflower, Radishes, Corn, Snapdragons, and other vegetables and flowers. The hard and brittle layers in soil that roots and water can't penetrate because it is so dense and compact. Used to describe the condition of a substance within a mixture when it isn't chemically combined with other components of the mixture.
Friable soil crumbles easily when worked with a spade, fork, rake, etc.
The opposite is a tenacious, clayey soil. The particles of this soil cling together forming clods that are difficult to pulverize. A leaf of a palm or fern. A group of fronds. Coming into leaf.