Corking? Or Trouble?

[From0to10in2weeks]

Hi all,

The base of this Espostoa guentheri yellowed in the past weeks. It's not soft/mushy. But I'd also be surprised if it is corking since the plant is still relatively small (about 10 cm in height). What do you think?

Thanks. Best.

[A_G_R]

Corking

[Steve Johnson]

Corking

Agreed. Premature corking is usually caused by any one of the following problems:

• For good or ill, everything starts out in the roots. Check to see if the roots are healthy and growing well. If they're not, you'll need to find out why.

• Watering with hard tap or well water. Mineral buildup in the mix slowly robs the roots of their ability to take up water and nutrients from a fertilizer. If that's the case, look for under-developed root systems. Watering your cacti with rainwater or distilled water is best, although maybe not an option for you. If you'd like to investigate the possibility of acidifying your tap water, this might give you some good ideas:
  
  http://www.cactiguide.com/forum/viewtop ... 25&t=43525

• Using the wrong fertilizer. The "ideal" NPK ratio for cacti is 1:0.4:1.5 -- P lower than N, and K higher than both. High-P fertilizers may be fine for nonxeric plants when they're blooming, but they inhibit healthy long-term root growth in cacti and succulents.

One question -- does your mix drain freely, or does it take a long time for the water to drain through? Free drainage is key, and too much soil in a cactus mix will suffocate the roots. Hopefully this isn't a problem for you.

[MikeInOz]

In August in the Northern Hemisphere, most cacti should be in full growth (unless the summer has been particularly hot in which case they take a rest before starting up again when the nights cool down a bit) Looking at the top of the plant, I cannot see much evidence of new growth at the top therefore (if it has not been very hot) the plant has stalled for some reason. This can be caused by too little water or too little Nitrogen or not enough nutrients in general or a lack of one or more particular element. Or damaged roots of course. If it is growing in a soil-less medium the feeding must be very good. Leaching of the following occurs first - sulphur, phosphorus, nitrate N, molybdenum, and boron - when you use plain water.
If the cactus is not growing vigorously (without interruption) when it should be, corking at the base can (will!) result. Remember also that if there is not enough N, P, K, Mg or Mo, available, plants remove them from the older parts to feed the growing points.
If you want less trouble generally, use 10-15% soil and/or humus in your mix.

[From0to10in2weeks]

Corking

Thanks

[From0to10in2weeks]

Agreed. Premature corking is usually caused by any one of the following problems:

• For good or ill, everything starts out in the roots. Check to see if the roots are healthy and growing well. If they're not, you'll need to find out why.

• Watering with hard tap or well water. Mineral buildup in the mix slowly robs the roots of their ability to take up water and nutrients from a fertilizer. If that's the case, look for under-developed root systems. Watering your cacti with rainwater or distilled water is best, although maybe not an option for you. If you'd like to investigate the possibility of acidifying your tap water, this might give you some good ideas:
  
  http://www.cactiguide.com/forum/viewtop ... 25&t=43525

• Using the wrong fertilizer. The "ideal" NPK ratio for cacti is 1:0.4:1.5 -- P lower than N, and K higher than both. High-P fertilizers may be fine for nonxeric plants when they're blooming, but they inhibit healthy long-term root growth in cacti and succulents.

One question -- does your mix drain freely, or doe it take a long time for the water to drain through? Free drainage is key, and too much soil in a cactus mix will suffocate the roots. Hopefully this isn't a problem for you.

Thanks for the extensive answer and suggestions! Some answers in order:

• I'll check the roots tomorrow.

• I've actually started using distilled water in mid-July. Before then I used acidified tap water.

• I am using fertilisers from two cacti nurseries:
  A) Kakteen Uhlig: 2.3% N, 2.3% P2O5, 1,8% K2O, and trace elements. Dosage: 3 ml/1 l water once a month.
  B) Kakteen Matk: 3% N, 5% P2O5, 7% K2O, and trace elements, Dosage: 5 ml / 1 l water, weekly
  The last time I fertilised was on 27. June with A). Before I used B). I changed because I was worried the latter was too much.

• But I also use in addition a product based on horsetail extract (Neudorf Schachtelhalmloesung). 0.5% N, 0.15% P2O5, 1,5% K2O. No indication about trace elements. Dosage: 4 ml / 1 liter water, every 10 - 14 days. Last time I used that was 11. July and 01. August.

• As substrate I use a 2:1 mix by volume of Seramis Kakteen Substrat and a peat-free general purpose soil. Yes, it drains well. But I actually do a 60 min bottom soak and then place the pots on paper towels to drain excess water from the pot.

Thanks. Best.

[From0to10in2weeks]

In August in the Northern Hemisphere, most cacti should be in full growth (unless the summer has been particularly hot in which case they take a rest before starting up again when the nights cool down a bit) Looking at the top of the plant, I cannot see much evidence of new growth at the top therefore (if it has not been very hot) the plant has stalled for some reason. This can be caused by too little water or too little Nitrogen or not enough nutrients in general or a lack of one or more particular element. Or damaged roots of course. If it is growing in a soil-less medium the feeding must be very good. Leaching of the following occurs first - sulphur, phosphorus, nitrate N, molybdenum, and boron - when you use plain water.
If the cactus is not growing vigorously (without interruption) when it should be, corking at the base can (will!) result. Remember also that if there is not enough N, P, K, Mg or Mo, available, plants remove them from the older parts to feed the growing points.
If you want less trouble generally, use 10-15% soil and/or humus in your mix.

Thanks for the suggestions. Yes, I noticed that this guy stopped growing sometime in June. That month was very hot here in Berlin. Please see above my response to SteveJohnson about details re fertilising and soil. Since end of May I water almost weekly.

Best.

[Steve Johnson]

• I am using fertilisers from two cacti nurseries:
  A) Kakteen Uhlig: 2.3% N, 2.3% P2O5, 1,8% K2O, and trace elements. Dosage: 3 ml/1 l water once a month.
  B) Kakteen Matk: 3% N, 5% P2O5, 7% K2O, and trace elements, Dosage: 5 ml / 1 l water, weekly
  The last time I fertilised was on 27. June with A). Before I used B). I changed because I was worried the latter was too much.

• But I also use in addition a product based on horsetail extract (Neudorf Schachtelhalmloesung). 0.5% N, 0.15% P2O5, 1,5% K2O. No indication about trace elements. Dosage: 4 ml / 1 liter water, every 10 - 14 days. Last time I used that was 11. July and 01. August.

A couple of things to be aware of -- first, see this:

https://www.gardenmyths.com/fertilizer- ... ally-mean/

Unless the labels show element values for P and K, the calculations you read in that article will give you those values. Going by your Kakteen 3-5-7 and Neudorf Schachtelhalmloesung 0.5-0.15-1.5, the NPK total is 3.5-5.15-8.5. %P205 x .436 = 2.2454% P, and %K2O x .83 = 7.055% K. Using N as a constant of 1 and we do some rounding, the NPK ratio is 1:0.64:2.02. P is lower than N, but a bit higher than I'd like. K seems too high, but I may be unduly strict about that. Mike has a lot more experience with ferts than I do, so if he says "good enough", you're fine on the NPK side.

The other side of the equation has to do with how much you're diluting -- N should be 50-100 ppm in your watering solution. You can go a bit lower, but you don't want to go higher. If you do, you'll end up with overfed, unnatural-looking cacti. If I was using your ferts, I would dilute 1 teaspoon per gallon of water for each product -- I believe it works out to 48 or 49 ppm N. 1 gallon = 3.785 L, and 1 teaspoon = 4.929 mL. Unfortunately, that's as far as my math skills go -- if you can calculate the dilution for mL/L from those numbers, you'll be set.

From all the fertilizer discussions I've seen, everyone talks about NPK, but that's only part of the story. The only way to get the full story is with a detailed chemical analysis of the ferts we're using. Some manufacturers have it on their product labels, while others (in my case, Dyna Gro) will have it on their websites. If you post photos of the chemical anaylsis for the products you're using, we'll see it and go from there. Hard to properly evaluate ferts without all the details.

[From0to10in2weeks]

Thanks Steve for the coaching. To clarify, I never use more than one product at the same time.

Your suggested ratio is roughly 4 times more dilute than than the recommended dosage. But how often would you apply this dilution?

The info I provided about the composition of the respective additives is correct. The labels on the bottles state as such.

Background: PhD chemist. Though it’s been awhile since i spent much time with the analytics of aqueous solutions…. So, in principal I know how to read chemical compositions. Though “K2O” is very weird to me. That “species” certainly doesn’t exist in nature. Or common chemical nomenclature. There is a gap between horticultural and scientific terminology. Some day I will make an attempt to understand this…

I am following with interest your recommendations hhow to mix custom fertilizers. I certainly agree with your suggestion to make large batches. That will reduce the error introduced. Even better would be to normalize on weight instead of volume. That will reduce errors due to different temperatures.

Getting compositions in the ppm level correct is not trivial. Especially with household type of equipment.

If you can you should submit samples of your recommended dilutions to an analytical lab to determine how close they are to specifications. But most likely you’re doing that already.

Best

[jerrytheplater]

0-10/2

Fertilizer A dosed according to the label gives 69 ppm N in the fertilizing solution. Label says dose 1x/month.

Fertilizer B dosed according to the label gives 150 ppm N in the fertilizing solution. Label says dose weekly.

Horsetail dosed according to the label gives 20 ppm N in the fertilizing solution. Label says dose every 10-14 days.

Steve is suggesting using B and Horsetail. A rough mixture would be to use 1.5 ml of B and 8 ml of Horsetail per 2 liters to come close to 50 ppm N in your watering solution. We are not trying to be analytical but close enough.

[Steve Johnson]

Your suggested ratio is roughly 4 times more dilute than than the recommended dosage. But how often would you apply this dilution?

Of the 68 cacti in my collection, I'm growing 65 in a 60% pumice/40% granite gravel mix. It's an essentially hydroponic approach, so I would have to apply that dilution with each watering in the growing season. The other 3 cacti are growing in a 50% pumice/50% soil mix. They get fertilized every time they're watered as well. Theoretically they might be overfertilized, although none of them are showing any ill effects from it -- this is after 9 years of following the same fert regimen for all of the plants.

If too much soil in your mix is inhibiting more robust root growth (that's my suspicion), Mike came up with a good suggestion about reducing the amount of soil to 10-15% vs. the higher amount you're using. In that case, I would recommend fertilizing with every other watering. And I believe Jerry has the dilutions right.

The info I provided about the composition of the respective additives is correct. The labels on the bottles state as such.

You may have misunderstood my reason for seeing a detailed chemical analysis of your ferts. Here's the one for the Dyna Gro All Pro 7-7-7 I use:



As I said, NPK is only part of the story, so the other parts shown here are the minor and micronutrients. Calcium, Magnesium, and Sulfur are important minor nutrients for cacti. The Ca and Mg amounts are good, and so is the Ca-to-Mg ratio of 4:1. The trace amount of S in the 7-7-7 isn't enough, so I corrected the S deficiency when I started supplementing the 7-7-7 with Potassium sulfate to bring the K side of the ratio up from 1:0.4:0.83 to 1:0.4:1.5. If your NPK balance is good, my only concern would be if you have Ca, Mg, or S deficiencies in your ferts. Assuming that you don't have any problems there, I think the premature corking is being caused by too much soil in the mix -- give Mike's suggestion a try.

[From0to10in2weeks]

Hi All,

It looks root bound. The entire ball came out of its pot intact. At first, I was a bit concerned about the "fuzzy" appearance of the roots. But I figure these are the roots hairs. Besides that nothing caught my attention. Nothing moldy. No bugs. No smell.

The white stuff are 3 rock chips to cover the drainage holes of the pot.

Can this limit the growth? Thanks. Best.

[From0to10in2weeks]

If too much soil in your mix is inhibiting more robust root growth (that's my suspicion), Mike came up with a good suggestion about reducing the amount of soil to 10-15% vs. the higher amount you're using. In that case, I would recommend fertilizing with every other watering.

Why would too much soil constrain root growth? And looking at the photos, it seems it had no problems growing roots in that mix for the past year. It's in a small pot though (dia: 6.5 cm / ~2.5 in).

You may have misunderstood my reason for seeing a detailed chemical analysis of your ferts.

Yes, sorry. I've attached a photo of the label of the Matk fertiliser (the 3-5-7 mix). The others don't give any info, also not on their websites.

Thanks. Best.

[Steve Johnson]

Why would too much soil constrain root growth? And looking at the photos, it seems it had no problems growing roots in that mix for the past year. It's in a small pot though (dia: 6.5 cm / ~2.5 in).

When airspaces around mineral gravel (in my case pumice and granite, in your case Seramis) are filled by too much soil, root growth is inhibited by poor aeration. It doesn't mean that your Espostoa isn't growing roots, but the pot should be filled with them. I have a Mammillaria crucigera that needed a bigger pot in April 2015, so here's what came out of its potful of soil-less mix:



Looking at the photos of your unpotted E. guentheri, 3 things come to mind:

• Root hairs are the transport mechanism that takes water and nutrients up into the stem of the plant. The multitude of root hairs giving a fuzzy appearance to the roots is exactly what you see. Excellent. When cacti go dormant in Fall and Winter, the root hairs die. Although some species need occasional sips to keep their roots alive during dormancy, most need to stay completely dry until their roots start growing new hairs in the Spring. You may already know this, so what I just said is for the benefit of beginning growers who make the mistake of drenching their cacti in Fall and Winter as they wonder why their plants end up rotting.

• Your guentheri's root system should be more extensive than it is. This makes a good argument in favor of what Mike suggested.

• Pot diameter looks good, but you could use a deeper pot. Free the roots from the mix, let them hang down, calculate a margin of 1-2 cm. below the tip of the lowest root, and find a pot with enough depth to accomodate that margin. If you can't get one that has the "ideal" depth, not the worst thing in the world if the roots touch the bottom. What you don't want to do is cram the plant back into its current pot.

Yes, sorry. I've attached a photo of the label of the Matk fertiliser (the 3-5-7 mix). The others don't give any info, also not on their websites.

No worries. And no disrespect to Kakteen, but you might want to ask them about why they don't have any Ca, Mg, or S in their fertilizer. I selected Dyna Gro 7-7-7 precisely because of its comprehensive nutrient profile, and that's what you should be aiming for. Awfully nice if you can get all the major, minor, and micronutrients with the correct amounts in the same fert. If this isn't possible for you, I wouldn't give up on the Kakteen Matk and Neudorf Schachtelhalmloesung ferts (must be in combination for better NPK balance -- I believe Jerry's calculated dilutions apply to the combo). You can address the lack of Calcium and Magnesium with a Cal-Mag fertilizer supplement. Here's a good one which I believe you can buy in Germany (from Amazon perhaps?):

https://www.premierhydroponics.com/shop ... ca-calmag/

4% Calcium, 1% Magnesium. Those are the proper amounts and the Ca-to-Mg ratio is perfect, so I would go with Jerry's dilution of 1.5 mL per 2 L of water. (My math is sometimes a bit suspect, so he might want to check it.) Per his caution here, applying the NPK and Cal-Mag ferts in the same watering will create an insoluble Calcium phosphate precipitate which you'll want to avoid. Such being the case, I'll recommend that you alternate between the NPK and Cal-Mag -- fertilize with the NPK ferts, fertilize with the Cal-Mag fert in the next watering, go back to the NPK ferts with the watering after that, and so on. (Am I making any sense?) The only thing we're coming up short on is Sulfur, but I don't have any ideas about what you can do to address the lack of S. S deficiency will eventually lead to pale-looking cacti, so hopefully you might be able to find a viable solution before this becomes a problem.

By the way, if your mix leaves any moisture at the bottom of the pot whenever you water, I'd also recommend that you water a little less frequently. Hint: Desert cacti are highly efficient at seeking out water under arid conditions in the wild. Cacti grown from seed under cultivation share the genetic heritage of their wild ancestors, so if the roots of your cacti are allowed to go completely dry before they're watered again, they'll grow to their optimal limit as they seek out water in a lean or soil-less mix. However, there is a constraint -- unlike cacti having a free run of the roots in open ground, pots constrain where the roots can go when they grow. The 2 extremes are pots filled with nothing but roots (a rootbound condition), and pots with a volume that's well beyond their root systems' ability to "wick" water up from the mix as it dries out (an overpotted condition). Selecting pots that are neither too big nor too small for the roots will be up to the grower's sound experience-based observations and judgment. Assuming that you have the pot sizes, mix, and fertilizers right, you'll do well if you abide by a nugget of wisdom about how to approach watering -- when in doubt, don't. I can't tell you how many times this has saved me from making potentially catastrophic mistakes.

[Steve Johnson]

Well, I'll be jiggered -- completely forgot about Epsom salt, which is Magnesium sulfate, highly soluble and easily available. From0to10in2weeks, that solves the sulfur problem, although you'll want to add a little bit of it to your watering solution with the NPK ferts, not the Cal-Mag fert. I believe that 15 ppm. S should be sufficient, but unfortunately I don't know the dilution for the right amount you'll need.