Root rot or just overwatered? And why are roots growing out the top?

GROWER ANSWER

Usually it's a pot that stays too wet, not rot. Both start with roots that can't get air. Overwatered roots recover once the pot dries back. Rot is what can follow when they sit starved of air too long: roots start to die and break down, and disease moves in. Smell and feel tell you which one you have, along with how slowly the pot dries. Color alone doesn't.

Smell and feel tell on the roots.

Roots need air as much as water

Roots do their work on oxygen. When the mix stays soaked, the air spaces fill with water and the roots slow down. They can't move water even though the pot is full of it, so the plant droops like she's thirsty. Water in the pot isn't the same as water in the plant.

Every time the pot dries back, air gets pulled into the mix behind the water. That's where the roots breathe. Keep it soaked and they never get the chance.

Overwatered or root rot?

Overwatered: the pot is heavy, the leaves droop and hang heavy off firm stems, and it started after a watering. Let it dry back. An overwatered pot needs time, often several days, and longer in a big container or a cool room. Watch the pot getting lighter, not the calendar.

Root rot, the tells:

• The smell. A healthy root zone smells earthy. Rot smells sour, like a swamp. Sniff the drain holes.

• The feel. Healthy roots are white to cream and firm. Rotting roots are brown, soft and slimy, and the outer layer can slide off.

• The pot. It takes far longer to dry than it used to. Damaged roots drink less, so the pot stays wet, so the roots get worse.

• The droop. It doesn't lift after the pot dries back the way an overwatered plant does.

Don't panic over color by itself. Roots that touch light and air often turn tan on the outside and are fine underneath. Texture and smell are what tell on them. If you want to look, slide the plant out of the pot gently, take a look and a sniff, and put it right back.

Getting air back to the roots

Whatever you find, the first moves are the same, and they're also how you prevent it:

1. Stop watering on the droop. A heavy pot with a droopy plant gets nothing until it's lighter.

2. Let it dry back. Lift the pot. Water fully when it's noticeably lighter, then let it get lighter again.

3. Give it somewhere to drain. Empty the saucer. A pot sitting in its own runoff never breathes. Raise it off the floor if you can.

4. Keep air moving gently over the pots, and keep the room steady.

5. Watch the root zone temperature. Roots in pots do best at about 68 to 75°F. A pot on a cold floor dries slowly and works slowly.

A good mix holds about 10 to 20% of the pot as air right after it drains. Mixes settle and lose that air over time. If the mix itself has packed down, an early repot into fresh, airy mix can help, but it's a last step, after you've fixed the watering. Give her 5 to 10 days after a repot before the next big change, and don't repot deep into flower.

Why are roots growing out the top?

Usually that's normal. Roots go where the water and the air are, and the top layer of the mix is often both. Seeing roots at the surface doesn't mean rot.

Cover them with a thin layer of fresh mix so they don't dry out, and leave them be. Then do the checks above anyway: if the pot is heavy for days and smells sour, the top roots aren't your problem, the bottom ones are.

Small sips can push roots up too: a splash wets the top and skips the rest of the pot. Water the whole pot, then let it dry back.

In hydro, it's faster

In a reservoir system, the water is the root zone. Keep it under about 68°F, since warmer water holds less oxygen. If a pump or air stone stops, act within hours, not days: air back into the water first, then check the roots.

What not to do

Don't water a heavy, droopy plant. That's how a wet pot becomes a rot problem.

Don't feed your way out of it. A stronger feed onto roots that can't breathe turns one problem into two.

When it's something else

• Droop and watering in general: see How often should I water, and why is she drooping?

• Out of room in the pot: see What size pot, and when do I pot up?

Keep going

Fabric or plastic pots, saucers and pot risers: see our pots and containers shelf guide.

Watch the episode: Heavy Pot, Droopy Plant, What's Actually Going Wrong on MyRemy Live.

A pot that dries back, roots that breathe, one change at a time. The whole system for a steady grow is written down in the free Stability Playbook. Get the free Stability Playbook

More answers: all grow guides. Every shelf guide and maker feed chart: Grower Resources.