Dead top – should it be cut?

[signal]

This cacti went through a period of neglect and the top of it has turned brown. It’s probably 3 feet tall and the top foot is like this. Would it be best to chop it off and hope for regrowth?

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[7george]

oh, yes. And check if the rot is going down the stem.

[Steve Johnson]

What I'm about to say is not negative criticism, just an observation...

1 plant = cactus, 2 or more plants = cacti. Based on many years of experience in the hobby, I've found that people who don't know the difference usually don't know much about the needs of the plants they're trying to grow. With that in mind...

You're growing your cactus in the wrong mix and it's seriously deficient in nutrients. I can guide you on what to do:

• Your cactus is a desert species, and the roots of desert cacti get suffocated in potting soils. When you add some sort of mineral gravel to the soil, the mix drains freely and their roots get the aeration they need for healthy growth. Pumice gravel is excellent, and if you can't buy it at your local nursery, go to Amazon:
  
  https://www.amazon.com/s?k=pumice+for+p ... _sb_noss_1
  
  My default recommendation is 60% pumice and 40% soil, although you could go a bit leaner with 70% pumice and 30% soil if your area tends to be humid.

• Cacti being grown under pot cultivation need to be periodically fertilized in the spring-summer growing season. However, you can't go with just any old fert, and fertilizers suited for cacti need to follow this basic "rule of thumb" -- P (phosphorus) lower than N (nitrogen), K (potassium) higher than both. Oddly enough, we do have an orchid fert with the NPK balance more suitable for your cactus:
  
  https://www.amazon.com/Fertilizer-13-3- ... 725&sr=8-5
  
  Water-soluble granules, dilution is 1/4 teaspoon per gallon of water. I only use liquid concentrates, so I don't know how long it'll take for the granules to dissolve. Shouldn't take long, though. If you water every 2 weeks during spring and summer (my recommendation based on using a lean mix), fertilize with every other watering.

Before you're ready to follow through on what I just described, you'll need to A. take the cactus completely out of its pot, and B. clean the soil out of the roots as thoroughly as possible. These are what well-cleaned roots look like:

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If the roots look white and fuzzy, you're dealing with root mealybugs. Remedy -- soak the roots in 2% soap solution for about an hour. Plain dish soap is fine, insecticidal soap even better. Let them dry out completely after they're clean. Next, sterilize a sharp knife with alcohol and cut below the dead part of the stem like this:

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The angled cut prevents water from accidentally pooling up at the top. Give the freshly exposed tissue a liberal dusting of sulfur powder like this:

Echinocereus_pectinatus_'Coahuila'02062015_04.JPG (152.57 KiB) Viewed 2264 times

The sulfur powder prevents fungus and mold from taking ahold of the tissue that was exposed by the cut. Stagnant air in the house can lead to fungus/mold problems, so give the cactus some ventilation while the cut dries out and forms a hard callus.

Once you clean the roots and do the cut, post a photo of the cactus roots and all before you repot. A pot that's too big for the plant will be counterproductive, so I'll guide you on how to determine the right pot size based on your photo, then you can repot.

A final question for the moment -- do you keep your cactus outdoors in the spring and summer, or do you keep it in the house all year?

[signal]

I assure you I know the difference between “cactus” and “cacti”, I guess it was just an autocorrect error from a quickly-typed post

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But, you are correct that I have little knowledge of cacti, so any advice is certainly welcomed. I appreciate you taking the time to help me. These were “rescued” from an office renovation years ago where they weren’t well cared for, though I probably haven’t done much better for them lately as they’ve been left at my parents’ house for the last several years. I don’t think it got enough sun or water during that time. This was one of several, but the only one of this particular type. It was my favorite, due to its almost “fuzzy” spikes that you can run your hand over, so I hope it can be saved.

I did repot all of them after I got them, including cleaning the soil off of the roots, replacing the soil (with some generic cactus soil from Lowe’s), and mixing it with rocks. This was years ago though. I have never added any fertilizer, and they have always been kept inside.

I should also note – as mentioned, it wasn’t well cared for before I got it either. The bottom foot of its “skin” was “callused” already (quotes because I’m guessing there is proper terminology for these things that I don’t know). So now it is basically just the middle foot of this 3-foot cactus that is still green. Is that bad news for its potential recovery?

[Steve Johnson]

Ah yes, autocorrect...

The bottom foot of its “skin” was “callused” already (quotes because I’m guessing there is proper terminology for these things that I don’t know). So now it is basically just the middle foot of this 3-foot cactus that is still green. Is that bad news for its potential recovery?

The bottom foot of the stem isn't callused -- the correct term is "corking" (the skin looks sorta like a cork). This is a normal age-related condition in many desert species, although not normal for cacti that haven't been grown well under pot cultivation. For good or ill, everything starts out in the roots, so the corking you see is due to poor root growth. Not life-threatening, but...

As I said on 2/10, you'll need to take the cactus completely out of its pot and clean the soil out of the roots as thoroughly as possible. When you do, post a photo of the cactus bare roots and all. Once I see what the whole shebang looks like, I can guide you on determining the right pot size -- be sure to give me the length of the stem and the length of the roots when you post the photo. My guess is that you don't have much of a root system to work with, so you'll want to avoid a pot that's way too big to promote good growth of new roots.

I did repot all of them after I got them, including cleaning the soil off of the roots, replacing the soil (with some generic cactus soil from Lowe’s), and mixing it with rocks. This was years ago though.

Soil breaks down over time, so cacti need to be repotted with fresh soil every 2-3 years. From what I've seen, most commercial cactus soils are actually horrible for cacti, but I think you'd be fine with Rosy Soil Cactus and Succulent Potting Mix:

https://www.amazon.com/Rosy-Soil-Cactus ... 0aWM&psc=1

Mix it with pumice, a 60% pumice and 40% soil mix will provide free drainage and good aeration of the roots. Repot in fresh, dry mix, then follow the cutting instructions I gave you on 2/10. Don't even think about watering until April or May. When your cactus starts growing new roots, it should start growing a new head on the cut sometime in the spring or summer.

I have never added any fertilizer, and they have always been kept inside.

Fertilizer is an absolute requirement, so go with the one I recommended and start fertilizing as soon as you start watering. Because your cactus has been nutrient-starved for years, I'll go even further by recommending that you fertilize with each watering until its skin is nice and green. Do the same with the rest of your cacti. Once they take on a healthy appearance, you can fertilize with every 3rd or 4th watering in the growing season.

Growing cacti indoors can be a challenge since they need plenty of sunlight. Your options are:

• A south-facing window. Experienced windowsill growers generally rotate their cacti once a month in the spring and summer.

• Full-spectrum LED grow light.

You'll find a good selection on Amazon:

https://www.amazon.com/s?k=grow+lights+ ... doa-p_3_11

Although your cactus doesn't look good, it's not dead yet, but prospects for a good recovery will depend on how quickly you can unpot the plant, clean the roots, and repot it with fresh cactus mix per my recommendations above.