What soil and drainage does citronella need and why is my grass turning yellow?

Citronella likes warm humid climates, full sun, and light, well drained soil; it tolerates a range of soils but does poorly in heavy waterlogged ground. Yellowing of the grass usually comes from one of three things: waterlogging or poor drainage suffocating the roots, nitrogen or general nutrient shortage in poor soil, or the natural ageing of an overgrown clump that needs cutting. Check drainage first, because standing water is the most common cause and shows as overall yellowing and weak clumps. If drainage is fine, yellowing often means the crop is hungry, so a balanced nutrient top-up (ideally based on a soil test or KVK advice for your area) greens it up; citronella responds well to nitrogen for leaf growth. If the clump is old and crowded with lots of dry yellow lower leaf, a clean harvest cut removes the old growth and the fresh regrowth comes up green. Keep spacing and airflow good to avoid fungal leaf issues that also cause patchy yellowing. So: fix drainage, feed if hungry, and cut on time to refresh the clump. For a precise fertiliser dose use your soil test and local recommendation rather than guessing.