Question

Brown damage   QUESTION: Hello from London, UK.  I really hope you can help - I have just noticed that my large 'cowboy cactus' has been turning brown on each side an inch or two above the soil.  The plant is about 3 feet tall and is otherwise healthy.  A day or two ago it was fine.  The weather in the UK is very cold and dark. I've not watered him since late October, my other cacti look fine. The brown parts are slightly less firm to the touch than the green flesh, it doesn't seem to be getting any worse.  Is it perhaps stressed by underwatering? Really appreciate your help, Best wishes, Julia

ANSWER: Hi Julia,

I love the UK.  This plant is not a cactus despite it's name.  It is Euphorbia ingens - a succulent - and the care is a bit different.  As for the browning, if it is soft and sudden I wouldn't attribute it to the corking that some older plants develop and is normal.

Though Euphorbias can go for fairly long periods and are winter dormant they still require some watering. Also, although somewhat cold hardy, this plant doesn't do well with prolonged cold. It does require sun so I'd put where you can get as much as possible.

Sorry to say, but I think this plant has developed some disease.  As I see it you have three choices. 1. see if the brown hardens up, which is doubtful. . I suspect it will spread 2. take it out of the pot and look at the roots to make sure they look healthy, and 3. take off some branches and start a new plant.  If it's isn't branched,  with a sterilized knife cut above the browning to healthy tissue and propagate with that.

Julia, why are you using a humidifier?

---------- FOLLOW-UP ----------


Big cactus   QUESTION: Hi Maureen,  sorry, I meant to say a dehumidifier (to suck water out of the air). The building I live in is old and prone to damp, although the room with the cacti in is quite dry. Bad news, I thought that it was going to be ok but the damage is now spreading across the base and I think I am going to have to cut the plant across, up a few inches from the rot, and make a new plant.  Having never done this before I am pretty nervous, but I have bought a good knife and surgical spirit to sterilise it with.  A friend who saw the plant said that the compost was just normal compost, and may have become waterlogged even though I haven't watered the plant since October.  I am now not sure if it is a cowboy cactus, it does look like one but has long spikes and doesn't have white liquid inside, rather it has water.  I've attached another photo.  

One question before I go ahead - I was unable to find rooting powder (the only one available wanted me to dip the cutting in water prior to using it so I didn't buy it), so I won't be using any - will this matter? Also, is it ok to do this now in a cold temperature (snowing here!)  I once took a small branch from another cactus and by the morning it had shrivelled up to a tiny twig - bit scared of that!  Thanks so much for all your help, best wishes Julia

ANSWER: Hi Julia,
 So the brown isn't hardening up? Rats.
 Get the rooting powder.  You don't have to wet it, you're just going to brush it across the wound to give its some protection as it develops a callous.
 It's always best to start a plant when it is coming out of dormancy in the Spring.  If your rot is spreading you won't be able to wait, but you'll have to move the cuttings to a warmer area.
 I wouldn't try to root that large a plant with the arms still attached. I still don't think you have a cactus but some kind of Euphorbia - cactus don't have individual spikes - but I try to find out more.  It doesn't make a big difference in rooting.  Cut them off and let them callous. I'd have them do this for at least a couple of weeks. As for the main stem, cut that at least 2-3 inches about the rot. If you still see a vasculature that has brown, black, orange coloring- any other than heathy tissue, keep cutting till you get there. Sterilize your knife each time. The bottom may be fibrous so you'd have to cut above that as well. You'll have to let that callous for a longer period because it is so large.  I've never had much luck with rooting a plant with a large base, but sometimes if you just rest it on top of the soil and stake it that works.
 Meantime,get some pots, not much larger than the cuttings and preferably plastic, put screening over the drainage holes and make up your mix.  To root cuttings, I'd try 1/3rd peat moss or coir, 1/3-1/2 perlite and 1/3-1/2 coarse sand- sifted builder's sand. Moisten it enough so that when you squeeze it it crumbles i.e. just slightly moist, and do that just before rooting.  Take each arm that has calloused (and I should have said to cut them so the are as straight as possible, plant 1-3 inches into the soilless mix (you'll probably have to stake these as well# place them in a warmer area in indirect light and wait. It can take months for these plants to root.  Occasionally mist them and resist the urge to water. When they begin to root you can gradually start to water.
 Just on the chance that this browning is hardening and may be just corking, before you go through all of the above you could take it out of the pot and check the roots.  If they  are white and fat and healthy you'd just have to repot the plant in a half perlite or sand and half soil-sterilized) in a pot that is 1/3rd the height of the plant with a base that is wider than you normally would use with a succulent.  Either way have your friend help you.
 I don't know what  happened with your other little plant that shriveled up over night - I've never seen something like that happen so fast.

Anyway, Courage! Keep me posted.

Maureen

---------- FOLLOW-UP ----------

QUESTION: Hello Maureen, good news, I carried out an 'amputation' and it went very well.  You were right, it is a Euphorbia - lots of white liquid came out but I had taken prior precautions so it was fine! The inside of the main stem was extremely healthy, I cut 2 inches above the rot, and found that from there upwards it was in perfect condition with no signs of the rot spreading.  The root ball was surprisingly large, with some signs of rot but the base of the stem only had another inch or so to go before it rotted right across.    I applied good rooting powder and will leave it  to callous over.  I decided that as it is such a beautifully shaped plant I would try to keep it as intact as possible.  If for some reason the surgery fails I will cut and root the individual arms.  Thanks for saving his life, I will update you again once I repot.  Best wishes, Julia

Answer
Go for it, Julia.  What is the diameter of the base?  I would just suggest you take an arm and root it separately, for insurance.  And don't forget it can take months sometimes for these plants to start anew, but they can live a long time without roots.  It sounds like you saved it in the nick of time, before it fell over!It. looks like the main stem could be rooted in the same pot if you sterilize it.  Be sure to throw that soil out.  Don't use it for anything as it's infected.

Very good luck, Julia.

Maureen

Thanks for not telling me in centimeters!