A cactus that has had too little water and a cactus that has had too much can look the same: shrunken and wrinkled. The fixes are opposite, so check the mix (the potting soil in the pot) before you water.
All of this is for a cactus that has roots. Give an unrooted cutting no water until it has rooted. Rooting generally takes 4 to 8 weeks. See how to root a cactus cutting.
The short version
- Push a finger or a wooden skewer 2 to 3 inches into the mix, or to the bottom of a shorter pot.
- Wrinkled plant, dry mix: it is thirsty. Water until water runs out of the drainage holes.
- Wrinkled plant, and the mix is wet because you watered in the last day or two: wait. Do not water again until the mix is dry. A thirsty plant fills out as it takes the water up.
- Wrinkled plant, and the mix has been wet for a long time (it was wet at your last check too, or you cannot remember it being dry): the roots have generally died from staying wet. Do not water. Take the plant out of the pot and look at the roots.
- A stem that is soft, dark or wet in any spot is rotting, whatever the mix feels like. See cactus rot.
- Roots all sound: let the mix dry fully, then fix what kept it wet. That is a pot with no drainage hole, a saucer left full, a mix that drains slowly or a pot too big for the roots.
- Some or all of the roots rotted: trim them off, let the cuts dry and replant in dry mix. A plant with no roots left is rooted again like a cutting.
- A cutting that has just rooted gets light waterings until it shows new growth at the tip.
Check the mix first
A skewer that comes out darker or damp means the mix is still wet below the surface. Lift the pot as well. A pot of dry mix is lighter than the same pot just after watering.
Then press the stem between the spines with a fingertip, on a wrinkled part and near the base. A thirsty stem may feel a little softer than a full one. A spot that is mushy, dark or leaking is rot.
Why the two look alike
A cactus stores water in its stem and draws on that store when the roots bring nothing in. As the store runs low, the stem shrinks and the skin wrinkles. In dry mix the roots have no water to take up. In mix that stays wet, the roots run short of air and die, and dead roots take up no water.
Signs of thirst
- The mix is dry all the way down and the pot feels light.
- The stem looks deflated. On a columnar cactus such as San Pedro, the ribs (the raised ridges that run up the stem) let the stem shrink as stored water is used, so the plant looks thinner and more deeply grooved.
- No part of the stem is mushy or discolored.
Signs of too much water
- The mix is wet or damp to the touch and has not dried between checks.
- The stem is yellowing, or it has soft or mushy places.
- The base of the stem is brown or black at the soil line.
- The skin has raised blisters or rusty, corky patches. These are often tied to too much water together with poor air movement. See corking, sunburn and rot.
- The stem has split. Some growers report splitting after heavy watering. Leave the plant unwatered until the mix is dry, and treat the split as rot if its edges turn soft or dark.
Yellowing with no other sign may be sunburn. Too much sun also turns a cactus yellow, on the side that faces the sun.
If it is thirsty
Pour water over the whole surface of the mix until it runs out of the drainage holes. Let the pot drain and empty the saucer. From then on, water each time the mix is dry 2 to 3 inches down. The method is in watering cactus.
A thirsty cactus generally fills out again once it has taken up water.
Cold weather is the exception. A cactus kept dry through a cold winter may wrinkle a little. If it lives outdoors or in an unheated space, do not soak it while nights are below about 60 F. See cactus winter care.
If the mix is wet and you watered a day or two ago
Wet mix this soon after watering tells you nothing yet. A plant that was dry and wrinkled before you watered may still be taking the water up.
Do not water again. Check the mix every few days.
- If the plant fills out as the mix dries, it was thirsty.
- If the mix dries and the plant is no fuller, the roots may not be taking water up. Roots that have been dry for a long time can die. Take the plant out of the pot and look at them.
- If the mix is still wet check after check, treat it as mix that has stayed wet.
If the mix has stayed wet for a long time
This is the mix that was wet at your last check and is wet again now, or that you cannot remember being dry. A wrinkled plant in mix like this has generally lost roots.
Do not water. Tip the pot on its side and slide the plant out, holding the stem with cactus gloves or a folded towel. Brush the mix off the roots.
Rotted roots are brown to black and soft or mushy. The outer layer often slides off and leaves a thin thread. Leave any root that is not like that.
If none of the roots have rotted, put the plant back and let the mix dry fully before you water again. Then fix the cause.
- The pot needs a drainage hole.
- Empty the saucer or tray after every watering.
- If the mix stays wet for a long time after watering, repot into a faster-draining mix. See cactus soil.
- A pot much larger than the roots tends to stay wet for longer. See pots and repotting.
If roots have rotted
If you are unsure what you are seeing, email us with photos at support@thoughtfulpricks.com.
- Wipe off any sap and dirt, then wipe the blade with 70% isopropyl alcohol so it stays wet for at least 30 seconds. Let it air dry.
- Trim off every root that is dark and soft. Leave the roots that are alive.
- Press the base of the stem. If any of it is soft or dark, the rot has reached the stem, and the soft tissue has to be cut away down to clean flesh. Follow the method in cactus rot before you go on.
- Keep the plant dry and in the shade until every cut is dry to the touch. It can stay out of the pot for several days or longer.
- Replant it in fresh, dry mix. Wait about a week before the first watering. After that, water when the mix is dry and nights are at about 60 F or warmer. In colder weather, leave it dry.
A plant with no roots left, or one that has had stem cut away, is a cutting again. Root it as you would any other: see how to root a cactus cutting.
After a cutting roots
A cutting that has just rooted has only a few thin roots, and a full soak may leave the mix wet for longer than those roots can use.
Make the first waterings light. Dampen the mix around the base of the plant and stop before water runs out of the bottom. Let the mix dry fully each time. Move to full soaks once the tip shows new growth.
If what you see matches neither thirst nor too much water, see cactus problems.
Sources
Cactus Care Tips from Garden Horticulture Staff. Desert Botanical Garden, 2023. https://dbg.org/cactus-care-tips-from-garden-horticulture-staff/
Common Problems and Issues of Succulents. Aaron Steil, Iowa State University Extension and Outreach, 2023. https://yardandgarden.extension.iastate.edu/how-to/common-problems-and-issues-succulents
Problems and Pests of Agave, Aloe, Cactus and Yucca. Jack Kelly and Mary W. Olsen, University of Arizona Cooperative Extension, revised 2011. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1399.pdf
How to Transplant a Cactus. Michael Chamberland and Jack Kelly, University of Arizona Cooperative Extension, 2020. https://extension.arizona.edu/publication/how-transplant-cactus
How to Propagate Agaves and Cacti from Cuttings and Seed. Jack Kelly, University of Arizona Cooperative Extension, 2009. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1483.pdf
Overwatered Indoor Plants. University of Maryland Extension, updated 2023. https://extension.umd.edu/resource/overwatered-indoor-plants
Root Rots of Indoor Plants. University of Maryland Extension, updated 2023. https://extension.umd.edu/resource/root-rots-indoor-plants
Cacti and succulents. Deborah L. Brown, University of Minnesota Extension. https://extension.umn.edu/houseplants/cacti-and-succulents
Cacti and Desert Succulents. Saguaro National Park, U.S. National Park Service. https://home.nps.gov/sagu/learn/nature/cacti-and-desert-succulents.htm
How to grow houseplant cacti and succulents. Royal Horticultural Society. https://www.rhs.org.uk/plants/types/cacti-succulents/houseplants/growing-guide
Cacti and Succulents. Texas Plant Disease Handbook, Texas A&M AgriLife Extension. https://plantdiseasehandbook.tamu.edu/landscaping/flowers/cacti-and-succulents/
Indoor Cacti. Karen Russ, Al Pertuit and Barbara H. Smith, Clemson Cooperative Extension Home and Garden Information Center, revised 2015. https://hgic.clemson.edu/factsheet/indoor-cacti/