My leaves are turning yellow. What's wrong?Updated an hour ago

It depends on where and when. Lower leaves yellowing in mid to late flower is usually normal: the plant is moving nutrients from old fan leaves into the flowers. Yellowing anywhere else is most often a watering or environment problem, so check those before adding any nutrients.

Check these first

1. Watering. Soil that stays too wet starves the roots of oxygen, and roots that cannot breathe cannot take up nutrients. Soil that dries out too far looks like hunger. Aim for no more than 5 to 10% of the soil volume per watering and an evenly moist pot.
2. Temperature. Cold soil slows the biology and the plant's nutrient uptake, even when the nutrients are there.
3. Light and environment. Light that is too weak, too strong, or too close can cause pale or bleached leaves.
4. Container size. A big plant in a small pot can outrun the soil.

Then consider feeding

• If watering and environment look right and the plant is big and still has weeks to go, it may be hungry. A top dress of Craft Blend and BuildAFlower is the usual fix.
• If you are within a week or two of harvest, let it finish.
• Avoid adding several new products at once. Too many inputs can cause more problems than they solve.

For a full walkthrough, read Diagnosing Yellow Leaves in Living Soil.

Still not sure?

Send us photos of the whole plant and close-ups of the leaves, along with your soil, container size, and how often you water, through the contact page or the chat button. If the same problem shows up every run, a soil test can help.

More on watering: Watering Protocol. More on environment: Environmental Protocol Indoors.