➤Cotyledon (a.k.a. seed leaf) A type of leaf appearing in an early stage of plant development, before the first true leaves appear. Seed leaves do not resemble true leaves.
➤Direct sow (or direct seed) To plant seeds in the same place where they will grow to maturity.
➤Germination The process by which a seedling sprouts from a seed
➤Sow To plant seeds
➤Thinning (a.k.a. pricking off, spotting out) Removing some seedlings (for example, every other seedling in a row of seedlings) because of overcrowded conditions or poor health/performance of the individual plants being removed. Thinning provides adequate space for the remaining seedlings to grow to healthy maturity. Because seed germination rates vary, it is common to sow more seeds than are needed, and then thin seedlings if germination rates are high.
True leaf (aka primary leaf) A type of leaf appearing after the cotyledon stage of plant development. True leaves are the foliage typically associated with a given plant.
Gough, Robert and Cheryl Moore-Gough. The Complete Guide to Saving Seeds. North Adams, Massachusetts: Storey Publishing, 2011.