QuickDrawDave
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Joined: Wed May 24, 2017 12:06 pm

Please help - cactus is yellow at the base

Hi, hope you can help me with my new cactus, I've had it about four weeks and while it is growing and looking healthy at the top, the base is yellow. How do I remedy this?

I may have over-watered it initially - I now give it less water but still water once a week, once the soil has completely dried. It gets light but I'm trying to avoid direct sunlight for now.

Will the correct amount of water eventually redude the yellowing, or is it something more serious?
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Amanda Doofenshmirtz
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Location: Twin Cities, Minnesota

Re: Please help - cactus is yellow at the base

Hello

I do not know as much about cacti, so I am just brainstorming here. Hopefully a cactus person will read what I am writing and help us both learn some things. The 1st thing that popped into my head was nitrogen. Without going back to look at my notes, I believe that a nitrogen deficiency effects the oldest part of the plant 1st, which is the bottom. Have you fertilized it since you got it? That would be something I would try if it were me.

I think you are on the right track with limiting the watering. It definitely likes to dry out between watering. I have an aloe vera that I usually forget about in the winter when i bring it inside. It will go with no water from November until March and it's always fine. Maybe try watering it once every 10-14 days for a while. I can imagine that if it needed water really bad, it would get wilty or mushy looking, and promptly watering it would cause it to plump back up. So I do not think you have to worry about under watering it, but instead worry about overwatering.

Make sure it does not have powdery mildew. I am battling an epidemic of powdery mildew that crept up on me during the cold months. All the plants on my sunporch were affected, but I didn't notice until it was really bad. My paddle plant's stem looks like a powdered doughnut, and I am dousing it in neem oil every other day and trying to brush off the white dust with a neem oil soaked paint brush. It's slowly coming off, and I can see green stem again. Keep an eye out for that, even if it is not the cause of the yellowing, the cactus could become susceptible. Luckily the neem oil seems to be really helpful for that. Best wishes!

imafan26
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Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Please help - cactus is yellow at the base

Over watered, you have a saucer under it, don't leave any water in the saucer. The pot is too big. More light.

If the bottom is not soft let it dry out
Your medium looks "organic". Try cinders or a cactus mix with a lot more perlite. I live in a wet place and I water every day. I use inders and rocks.
Get a pot that breathes. Insead of glazed ceramic, get a terra cotta pot and only big enough for the roots too fit. Cactus don't need all the extra space that is going to hold more water. I prefer the azalea pots that are more squat. If you have to use a saucer, get a big one and use pot feet to keep the pot out of the water. Drain the saucer of any water, cacti don't need humidity.
More light, more air
If the bottom is soft, it may be rotting. Cut off the rotting part and make sure you leave only healthy tissue. Use a clean sharp knife. Let the end callus of and dry for a few days or a week then repot as above. Cactus food once in a while. The easiest way to know when to water is to do the same thing that we do for orchids. Pick up the dry pot and feel the weight (or put it on a scale). Water the plants thoroughly until the water is running out the drain hole. Drain the pot for 30 minutes, pick it up again and feel the difference. When the pot feels light and ready to water, wait another day and take it to the sink; water and drain again. Cactus are high light plants so you need to have a light over them or in a bright window or better yet outside when the weather is nice.

Cactus and succulents are sponges, some of them can latch on to even the moisture from the air so you have to water sparingly, make sure the soil drains and it does not sit in water. They need a lot of light. Some succulents like lithops cannot be watered while they are shedding their leaves for about 3 months. I know, I killed one because I forgot to bring it back inside one night and it rained. I know someone who has an window collection of mini cacti and he actually wipes the succulents with a paper towel after they are watered to remove any excess water from the plant. Cactus can tolerate being underpotted but will rot if you have too much wet media in a big pot.
Happy gardening in Hawaii. Gardens are where people grow.

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