When plants first begin growing from seed, or germinating, they have all the nutrients they need stored directly in the seed. As the plant grows, however, the seed runs out of stored nutrients, and the young plant requires more nutrients to continue developing.
This is when plant food comes in, and detecting when your plants are ready for it is key to growing healthy plants.
The 3 Signs of Plant Food Readiness
You only need to see 1 of the 3 signs to know your plant is ready for plant food.
1. True leaves
True leaves are the second set of leaves to grow after the first leaves, which are called cotyledons. While cotyledons may not resemble the mature plant's leaf shape or color, true leaves do. If you're unsure what your plant looks like when mature, check out its page in the Plant Book. When you see 1-2 mini leaves that resemble the mature leaf shape, those are the true leaves.
Kale cotyledons (left) and later with true leaves (right)
2. Roots growing 1-inch long out the bottom of the yCube
Sometimes plants grow faster beneath the surface - or in yCubes' case, below the rockwool - than they do above the surface. If some of your sprouts appear to be growing slowly, you can always check for root development - you might be surprised by what you find!
Roots growing out the bottom of a Swiss Chard yCube
3. Yellowing cotyledons
While cotyledons have all the nutrients a young sprout needs in its early stages of growth, they can't perform photosynthesis. As a sprout grows true leaves, the cotyledons' nutrients naturally run low as the plant prepares to transition to making new food through its true leaves' ability to perform photosynthesis. This transition period can lead to yellowing, withering cotyledons, indicating the young plant is ready for additional nutrients to continue developing.
Yellowing cotyledons after a true leaf has grown
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