Plant Selection and Horticulture
Plant selection questions reward matching plant to site: light, soil, moisture, hardiness zone, mature size, and maintenance tolerance. Know the difference between USDA hardiness zones (cold minimums) and heat/AHS zones, and that neither captures soil pH or drainage. Understand cultural requirements: full sun (6+ hours), part shade, and full shade; soil texture and drainage; and the fact that "drought tolerant" means established, not newly planted.
Traps: confusing sun/shade tolerances; ignoring mature size and root spread; selecting invasive species; and mixing up deciduous vs. evergreen function (screening year-round vs. seasonal shade). Questions may ask which plant solves a problem - e.g., a wet, shady corner - so reason from conditions to plant type rather than a favorite species. Know basic plant categories (canopy tree, understory tree, shrub, groundcover, perennial, ornamental grass) and their design roles.
Horticultural practice: correct planting depth (root flare at grade, not buried), proper mulching (2-3 in, pulled back from trunk), and the right-plant-right-place principle. Understand transplant shock, establishment watering (frequent deep watering in year one, tapering after), and why fall or spring planting reduces stress. Know that soil amendment and drainage matter more than fertilizer at planting.
Worked rule of thumb: space shrubs at roughly half their mature spread from center to center for a quick screen, but full mature spread for long-term health. For trees, keep at least the mature canopy radius clear of structures. If a question gives a 3-ft planting strip, do not specify a tree with a 30-ft spread.
Review native vs. adapted vs. invasive distinctions; exam questions often test whether a species is appropriate for the region and site, not whether it is pretty.