thanksgiving cactus- need help with an issue

[solj3]

this is my beautiful thanksgiving cactus. a dear friend gave it to me as a gift. i look forward to its flowers every fall. this summer i noticed this odd yellow fungus? not sure if mold? i would scrape it off but sure enough it comes back usually a day or so after i water it. i realized that i might be over watering it. i usually water it once a week in the summer and biweekly in the fall/winter/spring. so i have stopped watering it to try to “kill” the yellow moldy/fungal stuff and its been a good month no water. so i watered it 2 days ago and today the yellow moldy/fungal stuff is back. im back to square one so im holding back on water for another month starting today. i need to know if i should be worried about it and if there is any better way to treat it. thank you much

[Steve Johnson]

See this:

viewtopic.php?t=43819

Once we know your geographical location, members will be able to give you advice that's appropriate to where you live.

[solj3]

hello everyone, I’m in Rhode Island if that help narrow things down

[MikeInOz]

That is ''snow mold''. It usually develops in organic media which are not sufficiently composted or aged. It can be a problem if it spreads throughout the mix. The solution is to change the mix to a higher quality one. Drenching with dolomite solution and raising the EC of the mix by fertilizing may help.

[Steve Johnson]

That is ''snow mold''. It usually develops in organic media which are not sufficiently composted or aged. It can be a problem if it spreads throughout the mix. The solution is to change the mix to a higher quality one. Drenching with dolomite solution and raising the EC of the mix by fertilizing may help.

Hi Mike,

Please review this:

https://www.amazon.com/Cactus-Succulent ... F0aWM&th=1

There's no description of the ingredients in the mix, so I hope the photos you see on Amazon will be enough to tell you whether or not it's the higher-quality mix solj3 needs. I agree -- the mold is having a feast in that organic material.

[solj3]

thank you everyone! sounds like i need to change the soil. ill order the mix and get to work when it comes in. ill post updates.

[MikeInOz]

Hi Mike,

Please review this:

https://www.amazon.com/Cactus-Succulent ... F0aWM&th=1

There's no description of the ingredients in the mix, so I hope the photos you see on Amazon will be enough to tell you whether or not it's the higher-quality mix solj3 needs. I agree -- the mold is having a feast in that organic material.

I don't know whether that's a good mix or not Steve. The thing to know is that the organic part of the mix is ''mature'' and that means it has gone through a fairly long process of composting so that most of the readily decomposed things like sugars, amino acids and starches are consumed. Those are the kinds of things that the snow mold if growing on. In other words, a well matured compost is relatively stable and has a high population of bacteria which out-compete the fungi. I make my own, as here https://cactiguide.com/forum/viewtopic. ... st#p399980
Otherwise you can use a mix that is guaranteed by the manufacturer - if you can find one. In Australia, we have a Standard for potting mix which covers biological qualities, pH, nutrient balance, wettability, aeration, nitrogen drawdown, EC etc., and all mixes which conform to the standard are guaranteed by law to perform. The ones that don't are always a gamble.

[Steve Johnson]

I don't know whether that's a good mix or not Steve. The thing to know is that the organic part of the mix is ''mature'' and that means it has gone through a fairly long process of composting so that most of the readily decomposed things like sugars, amino acids and starches are consumed. Those are the kinds of things that the snow mold is growing on. In other words, a well matured compost is relatively stable and has a high population of bacteria which out-compete the fungi. I make my own, as here https://cactiguide.com/forum/viewtopic. ... st#p399980
Otherwise you can use a mix that is guaranteed by the manufacturer - if you can find one. In Australia, we have a Standard for potting mix which covers biological qualities, pH, nutrient balance, wettability, aeration, nitrogen drawdown, EC etc., and all mixes which conform to the standard are guaranteed by law to perform. The ones that don't are always a gamble.

You make a valid point, and I don't know if US laws cover the kind of standard you have in Australia.

solj3 -- before you commit to buying the rePotme Succulent Soil I indicated in the Amazon link, go here...

https://www.repotme.com/pages/contact-us

...and ask them for a guaranteed analysis of everything in the mix. If they can't provide you with one, you'll just have to chance it and hope that the mix performs well over time.

[greenknight]

When I used to make compost, I sifted what I used for potting mix through 1/4" hardware cloth, chunks that wouldn't go through that screen went back in the compost pile as they weren't broken down enough. A lot of commercial potting mixes I've seen could use that sifting.

[solj3]

ok, i will ask repotme.com for a guaranteed analysis of the christmas cactus mix.

[Steve Johnson]

ok, i will ask repotme.com for a guaranteed analysis of the christmas cactus mix.

I'll be interested in knowing what rePotme has to say about the mix, so please keep me posted. By the way -- if the mix looks like it'll work for you, it'll work for all of your jungle cacti. You can learn more about them here:

https://www.cactiguide.com/growcacti/

[solj3]

Hello everyone,

I got an answer from rePotme about the Christmas cactus mix. I will attach a screenshot of the email response.

[Steve Johnson]

Okay, at least we know what the ingredients are. Guaranteed analysis is required by state law for fertilizers, but apparently not for potting media. The only thing you can do is try the rePotme Christmas cactus mix for your Christmas and Thanksgiving cacti. Not sure if it's the best you can get, but certainly better than what you're growing them in now.

[solj3]

Yeah I have to try something. I wanna give my plant the best chance. Thank you everyone for your recommendations. I'll keep you guys updated on what happens.

[Steve Johnson]

Glad to help, and I have another recommendation for you...

When you unpot your cacti for repotting, first clean the existing soil out of the roots as thoroughly as possible. Let them dry out, then repot in fresh dry mix. You'll lose roots in the process, but don't worry -- your cacti will grow new roots. They should be ready for their first watering a week or two after you repot.

By the way, I saw your thread on the Succulent Growing Help forum. As FredBW pointed out, the Dynamite Cactus & Succulent Food is too high in nitrogen. I'll go even further by stating that it's too low in potassium. The basic rule of thumb for a well-balanced fertilizer is "P lower than N, K higher than both". This applies to all ornamental plants, not just cacti and succulents. Here are some good NPK numbers to look for:

5-4-9
6-4-10
7-5-12
8-6-14
9-7-16
10-8-18

You'll have to do some research and see if you can find a fertilizer with one of the above NPK numbers. If you're lucky enough to find an 11-8-19 or 12-9-21 slow-release fertilizer, this will make things easier. If not, but you find a water-soluble fertilizer with the right NPK number, dilution will depend on how much N is in the fert. If you need further help on this, let me know.