“As needed” means adjusting based on how your plant or lawn is actually performing—not just following a set schedule. If you notice signs like yellowing, browning, reddening, pale leaves, thinning, slowed growth, reduced flowering or fruiting, early drop in new growth, or twisting and misshapen leaves, it’s time to reapply sooner. If everything looks healthy, vibrant, and growing well, you can wait the full 2–3 weeks.