Landscape Planning and Plant Selection
Process and principles
The design sequence runs site analysis → program (client needs) → concept → design development → construction documents. Judge a plan against the classic principles: unity, balance, scale and proportion, rhythm, focal point, and simplicity. Functional diagrams (outdoor rooms, circulation, sight lines) should be resolved before plant selection begins.
Selecting plants
Match the plant to the site: USDA hardiness zone, AHS heat zone, sun/shade exposure, soil moisture and pH, salt and drought tolerance, mature height and spread, root habit, and invasive status. Group plants into hydrozones by water need so irrigation can be zoned realistically. Layer the composition - canopy, understory, shrub, herbaceous, groundcover - and plan for seasonal interest in form, texture, and color.
Worked example
A 20 ft × 30 ft bed = 600 SF. A 3-gallon shrub with a 4-ft mature spread spaced 4 ft on center occupies 4 × 4 = 16 SF per plant: 600 ÷ 16 = 37.5, or 38 plants in a strict grid. For a naturalistic bed, multiply by about 0.8 to account for irregular edges - roughly 30 plants. Always space to mature size unless the client accepts culling later.
Traps
Designing to nursery-can size produces an overcrowded bed in three years. Do not assume "native" means no irrigation, and do not rely on hardiness zone alone - a protected courtyard is warmer than the street side. Overlooked root spread causes heaving paving and foundation conflicts.