Mineral growth issue on surface

[Fohat85]

Dear all,

i'd like to share with you a issue i have with my seeds growth. In the last two years i observed the undesired formation of "mineral shell" (i guess) around the seedling (pls see the pic). it inevitably follows that the seedling "suffocates" and dies.
The mix for sowing that I use is based on lapillus and common soil while the outermost layer is zeolite.
Have you ever had this problem?

Thanks in advance

[BryanT]

I think it's possible you have too much fine dust in your mix.
Did you sift the mix and washed the zeolite to remove fine dust/particles before you use?

[Fohat85]

I usually use zeolite without further purification. I should try adding this step before to use it to verify if is the cause. Thank you for the suggestion.

[jerrytheplater]

I get similar mineral deposits in the seedling mix I made up. I used some triple rinsed Coir in it. I have sifted mine through a window screen to remove the fines.

I ended up flushing the seedling trays with rain water/dehumidifier/RO water multiple times till the water drained out of the pot. It dissolved the crust. I water with the same water. When I fertilize, I mix it with the rain water. I do see some of the mineral crusts forming after fertilizer. I am using a fairly dilute fertilizer. N is at 50 ppm.

[Fatich]

It seems its because of the hard water. (Second photo)

[Steve Johnson]

It seems its because of the hard water. (Second photo)

I zoomed in on the second photo -- hard to tell if the crusts are fertilizer salts or Calcium carbonate buildup from temporary hardness in the water. Could be a combination of both.

Fohat85 -- it would be helpful to let us know about your geographic location, so please see this:

viewtopic.php?t=43816

If you're watering with hard water, temporary hardness comes in the form of Calcium bicarbonate. When the water evaporates, Calcium carbonate left behind in (and on) the pot shows up as a white crust. Watering with rainwater or distilled/RO water eliminates that problem. Let me know if you're having a hard water problem and neither option is available to you. The other option would be to acidify your water, although my experience with that is confined mostly to nursery-grown cacti that were well past the seedling stage when I got them. If other members have good seed-growing experience using acidified water, they should be able to guide you.

Update: I just looked at your first photo, and it appears that you do have a hard water problem:

PXL-20230217-084517603.jpg (138.76 KiB) Viewed 4866 times

That white residue is Calcium carbonate, and it'll stop the germination process before the seedlings have a chance to grow.

[MikeInOz]

I have that happen sometimes too. It's usually calcium but not always. It could be any salt. K, Mg etc. Seedlings HATE it! Especially if it is alkaline. I would think about repotting these seedlings but if they are not set too low in the medium, you can top them with some coarser gravel. (coarser than the rest of the mix) This does two things. First, it does not allow the salts to be drawn all the way up to the surface, and second, because of that, they stay a little more damp there under the gravel mulch, and are more easily washed and leached away with subsequent waterings. The trouble with zeolite is that it is very absorptive and will continue to draw up dissolved salts to the surface where they solidify and form a crust. It always helps if you use plain solid quartz as a topping to stop this happening. Preferably about 5mm deep depending on the size of the seedlings.

[jerrytheplater]

I have that happen sometimes too. It's usually calcium but not always. It could be any salt. K, Mg etc. Seedlings HATE it! Especially if it is alkaline. I would think about repotting these seedlings but if they are not set too low in the medium, you can top them with some coarser gravel. (coarser than the rest of the mix) This does two things. First, it does not allow the salts to be drawn all the way up to the surface, and second, because of that, they stay a little more damp there under the gravel mulch, and are more easily washed and leached away with subsequent waterings. The trouble with zeolite is that it is very absorptive and will continue to draw up dissolved salts to the surface where they solidify and form a crust. It always helps if you use plain solid quartz as a topping to stop this happening. Preferably about 5mm deep depending on the size of the seedlings.

Thanks for the tip on the coarse quartz mulch. The old aquarium gravel from the 1960's to the rescue again. #3 Quartz.

[Fohat85]

It seems its because of the hard water. (Second photo)

I analyzed the well water I use for watering and the concentration of fluoride and arsenic is high (2,27 mg/L and 33 microg/L respectively).

[Fohat85]

I have that happen sometimes too. It's usually calcium but not always. It could be any salt. K, Mg etc. Seedlings HATE it! Especially if it is alkaline. I would think about repotting these seedlings but if they are not set too low in the medium, you can top them with some coarser gravel. (coarser than the rest of the mix) This does two things. First, it does not allow the salts to be drawn all the way up to the surface, and second, because of that, they stay a little more damp there under the gravel mulch, and are more easily washed and leached away with subsequent waterings. The trouble with zeolite is that it is very absorptive and will continue to draw up dissolved salts to the surface where they solidify and form a crust. It always helps if you use plain solid quartz as a topping to stop this happening. Preferably about 5mm deep depending on the size of the seedlings.

Thank you MikelnOz for the tips. I will definitely add solid quartz or similar. However, my concern remains because the saline concentration remains in the lowest layer of the soil and therefore I have to find a solution directly on the type of water I use.

[Fohat85]

i'm sorry i forgot to mention i still never fertilized seedlings to date

[jerrytheplater]

It seems its because of the hard water. (Second photo)

I analyzed the well water I use for watering and the concentration of fluoride and arsenic is high (2,27 mg/L and 33 microg/L respectively).

Davide

A very important analysis for you is Total Hardness and Alkalinity. Tests exist in the Aquarium hobby for both and are not too expensive, but they are also not super accurate. They will give you a good idea. I am pretty sure you will find you have very hard water. Do you notice mineral build up in tea kettles? How about your hot water heater?

Total Hardness can be broken down into Calcium and Magnesium Hardness. These two are the major ions that cause Hardness. They exist as Calcium and Magnesium Carbonate (or Bicarbonate really) If your pH is over 8.3 you will have Carbonate and Bicarbonate.

Alkalinity is the measure of Carbonates, Bicarbonates, and even Phosphates (besides a few others you should never see). This is your buffering system in your water. The test uses an acid to neutralize your water to a pre defined pH. It is often in the 4.5 area. The amount of acid used allows calculations to determine how much Carbonate etc was there in the beginning.

You say you have a well. Do you know the geology of the area around your well? What is your bedrock? That will also tell you what is in your water.

A water softener can be used to lower your Total Hardness, but they replace Ca and Mg with Sodium (or Potassium if you use KCl in the brine tank). I would not suggest doing that. A better system would be Reverse Osmosis. You could also collect rain water. If you use a dehumidifier, you can use that water if you make sure your coils are clean from dust and dirt, as well as the collection container on the unit.

[Fohat85]

It seems its because of the hard water. (Second photo)

I analyzed the well water I use for watering and the concentration of fluoride and arsenic is high (2,27 mg/L and 33 microg/L respectively).

Davide

A very important analysis for you is Total Hardness and Alkalinity. Tests exist in the Aquarium hobby for both and are not too expensive, but they are also not super accurate. They will give you a good idea. I am pretty sure you will find you have very hard water. Do you notice mineral build up in tea kettles? How about your hot water heater?

Total Hardness can be broken down into Calcium and Magnesium Hardness. These two are the major ions that cause Hardness. They exist as Calcium and Magnesium Carbonate (or Bicarbonate really) If your pH is over 8.3 you will have Carbonate and Bicarbonate.

Alkalinity is the measure of Carbonates, Bicarbonates, and even Phosphates (besides a few others you should never see). This is your buffering system in your water. The test uses an acid to neutralize your water to a pre defined pH. It is often in the 4.5 area. The amount of acid used allows calculations to determine how much Carbonate etc was there in the beginning.

You say you have a well. Do you know the geology of the area around your well? What is your bedrock? That will also tell you what is in your water.

A water softener can be used to lower your Total Hardness, but they replace Ca and Mg with Sodium (or Potassium if you use KCl in the brine tank). I would not suggest doing that. A better system would be Reverse Osmosis. You could also collect rain water. If you use a dehumidifier, you can use that water if you make sure your coils are clean from dust and dirt, as well as the collection container on the unit.

Again one time, your advice was very valuable.
I think I'll buy a no-professional pHmeter that can also tell me the hardness of the water (in ppm) and other properties.

[jerrytheplater]

Again one time, your advice was very valuable.
I think I'll buy a no-professional pH meter that can also tell me the hardness of the water (in ppm) and other properties.

I am not aware of any meters available to test Alkalinity. That number will tell you what is happening in your potting mix when you apply the fertilizer.

[keith]

In my seedling pots I get a little of that crusty buildup and it will often get on the spines . Usually not enough to cause problems. I guess I would try filtering the water for your seedlings or rainwater if its available ?