Underwatered Cannabis: Signs and How to Fix It

Your plant is drooping and the leaves feel thin and limp. If the pot is light, it is simply thirsty. This is the easier twin of overwatering, and plants usually bounce back within hours.

Cannie showing early underwatered — Early

Cannie showing advanced underwatered — Advanced

“I am limp and my pot feels light as a feather. Water, please!”

Where it shows

The whole plant droops.

What it looks like

Leaves droop but are THIN, limp and papery: pale, dull and matte with dry brittle edges, hanging slack. No shine anywhere.

How to confirm it

The whole plant droops.
Leaves are thin, limp and papery.
Leaves look pale, dull and matte, with dry, brittle edges.
There is no shine anywhere.
Lift the pot. A light pot with drooping leaves means underwatered.

Why it happens

Straightforward, and easier to fix than its twin. Small pots and hot tents dry out faster than most growers expect.

Waiting too long between waterings.
Small pots that dry out quickly.
Hot tents or strong lights that speed drying.
A plant that has outgrown its container.

How to fix it

Cannie's quick fix, in order:

Water thoroughly until you get 10 to 20% runoff, then let it recover. It usually perks up within hours.
Lift the pot to confirm. Light pot plus droop is underwatered.
If it dries out this fast repeatedly, the plant has outgrown its container.

Water thoroughly until about 10 to 20 percent runs out of the bottom.
Water slowly so it soaks in. Very dry soil can shed water at first.
Let it recover. It usually perks up within hours.
Use the lift test before each watering from now on.
If it keeps drying out this fast, move it to a bigger pot.

Organic options

Mulch

A layer of mulch on top of the soil slows evaporation and keeps moisture more even.

Worm castings and compost

Improve how well soil holds water. Mix into new soil or top dress.

Yucca extract

A natural wetting agent that helps water soak into dry soil. Follow the label rate.

Bigger container

More medium holds more water. Transplant when roots fill the pot.

Read and follow every product label. Organic friendly does not mean certified organic; check the listing if that matters to you.

Veg or flower?

Larger plants in flower drink much more, so underwatering often shows late in the grow. Repeated wilting in flower can stress the plant, so stay ahead of it.

Don't confuse it with overwatered

The droop is identical. Underwatered leaves are limp, thin and papery; overwatered leaves are firm, thick and glossy. Or just lift the pot. Read the overwatered page.

Prevent it next time

Check pot weight daily in hot weather.
Size pots to match plant size and room temperature.
Use a mix that holds moisture well.
Do not let soil fully dry before watering.

Questions growers ask

How much water should I give an underwatered plant?

Water until about 10 to 20 percent runs out the bottom. Pour slowly so it soaks in.

How fast will my plant recover?

Usually within hours. If it does not perk up, check for other problems like root damage.

Why does my plant dry out so fast?

It may have outgrown its pot, or the room is hot and dry. A bigger pot or cooler temps can help.

Where these figures come from

These points match published grow books, page by page. They are grower practice, not research: none of these books cites a study, so where science and the books differ, this page follows the science.

Lift the pot to confirm; light pot plus droop is underwatered. Danko (2018), e-book p. 27; e-book p. 54. Green (2001), p. 183. Paull and Zetta (2020), e-book p. 50.
If it dries out this fast repeatedly, it has outgrown its container. Green (2001), p. 331. Danko (2018), e-book p. 54; e-book p. 92 to 93.
Larger plants in flower drink much more. Danko (2018), e-book p. 91. Paull and Zetta (2020), e-book p. 68.
Small pots and hot tents dry out faster than expected. Green (2001), p. 184.
Do not let soil fully dry before watering. Green (2001), p. 183.
Mulch slows evaporation. Paull and Zetta (2020), e-book p. 133 to 134; e-book p. 139 to 140.

Books: Danko, Cannabis: A Beginner's Guide to Growing Marijuana (Hampton Roads, 2018); Green, The Cannabis Grow Bible (4th ed., 2001); Paull and Zetta, Foolproof Guide to Growing Cannabis (2020) and The Cannabis Grow Bible (2020).