When you’re starting seeds indoors, it can be hard to tell why a seedling doesn’t look quite happy. Most of the time, though, the problem isn’t a lack of nutrients.
Plants need the most nutrients when growth is fastest—when they’re building lots of new tissue—not when they’re still tiny. That’s why seed-starting mix is intentionally lower in nutrients: it nudges roots to explore outward and build a sturdier root system. If you sow straight into a slightly larger pot, you can use richer soil in the bottom and seed mix on top, so the plant can “find” more food when it’s ready. Using seed mix isn’t strictly necessary, though—many seedlings do fine in regular potting soil.
Bagged, pre-fertilized potting soil usually contains enough nutrients for a few weeks. During that time you normally don’t need to add anything extra—and extra feeding can actually stress young plants. By then, the seedling often is ready to be potted up into a larger container. That’s also how nutrients most often enter the system: through fresh soil. As long as roots still have room to grow, they’ll keep reaching new, nutrient-rich pockets. If you use your own soil, make sure it’s moderately enriched with compost or something similar.
So before you reach for the fertilizer, check the basics: light, watering, and whether the roots have both air and space — and let the plant find its own way through youth at a steady, unhurried pace.
