Bleached leaves. Too much light or nutrition problem?

[papheteer]

Some of my plants have bleached leaves. Some look almost white with most mottling gone. Especially on my parvis. The new leaves come out darker and greener though. I have tried adding some magnesium sulphate in my water but not much changed. What do u guys think?

here are photos of my fanaticum's leaves:

 

[eggshells]

What do you use for lighting? It looks like its not the lighting though. Because if it did. Top leaves will go change in colour first. I'm pretty sure that this is nutrient deficiency.

 

[papheteer]

It used to be 12 inches under a 2 bulb t5hos. Then I moved it about 6 inches under 4 bulb 32watts t8s. Leaves still bleached.

 

[SlipperFan]

Need nitrogen? Or magnesium?

 

[lepetitmartien]

No unwanted cold exposure?

How are roots?

(just covering all areas… sorry if dumb, I'm too sexy for my shirt

 

[papheteer]

No cold exposure. I grow them in the basement. It's recently repotted. Lots of roots.

 

[mrhappyrotter]

I'll defer to the experts, which I definitely do not claim to be. That being said, the photos do look awfully suspicious.

What's your fertilizing regime like in terms of type(s) of fertilizer used, how often and how much?

I don't have a lot of knowledge about nutrient deficiency in orchids -- mostly because I've not had much experience with it. However, in other plants, yellowing older leaves like that is a sign of nitrogen deficiency.

That doesn't necessarily mean that you aren't giving your plant sufficient amounts of nitrogen (or whatever nutrient). It could mean that the nitrogen source isn't readily available to the plant, for instance if the pH isn't correct for the form of nitrogen you're providing or because other nutrients are blocking it's uptake (i.e. nutrient imbalance).

Also, if the plants are under higher light conditions and therefore growing rapidly (or trying to grow rapidly), it could exasperate the situation.

Anyway, I'm sure someone more knowledgeable will chime in on this.

 

[papheteer]

I have been using k-lite at 1/10 -1/8 tsp per gallon of water. I also supplemented with crushed oyster shells. The one that i got was very powdery. I did notice that after putting it all the root tips stopped growing. I dunno if its coz of that.

 

[mrhappyrotter]

I've also been told, and read, that bark based mixes require higher nitrogen feeding rates than plants in other media. Not sure if this has been proven or debunked, but the reasoning is that the microorganisms that live on/in the bark and break it down consume a lot of nitrogen in the process, and can out compete plants in its uptake.

 

[Stone]

Yes more N. and I would recommend Ammonium or Urea added to your normal fertilizer. Or even better a slow release form like IBDU. Don't expect fast results. 3 months or more I would say. Its absolutely a fact the bacteria consume a lot of N and can totally starve a plant if not enough is added. Every organic ingredient has a different Nitrogen draw-down with peat very low and uncomposted bark very high.
Try to increase the N by 50 to 100% and see how the plant responds.

 

[Cochlopetalum]

I have been using k-lite at 1/10 -1/8 tsp per gallon of water. I also supplemented with crushed oyster shells. The one that i got was very powdery. I did notice that after putting it all the root tips stopped growing. I dunno if its coz of that.

I think your plants are a bit close to the light still and you are feeding at very a low rate. I would feed them a stronger solution around 1/3 tsp per gallon and rais the lights a bit more.

 

[Ross]

Another point to consider is when you are taking such a tiny sample (1/8 tsp.) of the fertilizer and mixing it up, it may not be balanced with the right proportions of nutrients. I recommend taking a larger amount, according to directions, and making a liquid concentrate. The concentrate should be closer to the formula of the fertilizer than a 1/8 tsp. scoop. Once you have the concentrate, feed at 75-100 ppm of N.

Also, what kind of water are you using?

 

[keithrs]

Possibly iron?

 

[Ray]

I think you have done a number of things that are combining to cause the issue:

►Powders can certainly negatively affect roots, often by desiccating them.

►Excessive calcium can interfere with magnesium uptake. Powders have a lot of surface area, after all, so maybe the oyster shell powder is interfering chemically, as well as physically.

►You are underfeeding. The K-Lite formula at 1/8 tsp/gal is only supplying about 20 ppm N. That might be sufficient for daily feeding, but not likely so for a less-frequent regimen.

on other comments:

►If you leave a plant in the same bark for a very long time, as it breaks down there will ultimately become a hefty population of lignin-consuming microorganisms that consume nitrogen. Modern, attentive culture, and better quality barks pretty much preclude that.

►I think Stone's suggestion is a good "quick fix", but if you supplement with urea, use it as a foliar spray, and it's not as well absorbed through the roots.

 

[papheteer]

Thanks guys!

 

[papheteer]

I think you have done a number of things that are combining to cause the issue:

►Powders can certainly negatively affect roots, often by desiccating them.

►Excessive calcium can interfere with magnesium uptake. Powders have a lot of surface area, after all, so maybe the oyster shell powder is interfering chemically, as well as physically.

►You are underfeeding. The K-Lite formula at 1/8 tsp/gal is only supplying about 20 ppm N. That might be sufficient for daily feeding, but not likely so for a less-frequent regimen.

on other comments:

►If you leave a plant in the same bark for a very long time, as it breaks down there will ultimately become a hefty population of lignin-consuming microorganisms that consume nitrogen. Modern, attentive culture, and better quality barks pretty much preclude that.

►I think Stone's suggestion is a good "quick fix", but if you supplement with urea, use it as a foliar spray, and it's not as well absorbed through the roots.

Ray i feed almost every time i water. I use RO with 20% tap water added. My tap water has TDS of 180.

I will try and feed more. Should i use 1/3 tsp per gallon everytime i water?

 

[papheteer]

Another point to consider is when you are taking such a tiny sample (1/8 tsp.) of the fertilizer and mixing it up, it may not be balanced with the right proportions of nutrients. I recommend taking a larger amount, according to directions, and making a liquid concentrate. The concentrate should be closer to the formula of the fertilizer than a 1/8 tsp. scoop. Once you have the concentrate, feed at 75-100 ppm of N.

Also, what kind of water are you using?

I always make a solution of 2 tsp to 500 ml water and take from it.

 

[Rick]

I have been using k-lite at 1/10 -1/8 tsp per gallon of water. I also supplemented with crushed oyster shells. The one that i got was very powdery. I did notice that after putting it all the root tips stopped growing. I dunno if its coz of that.

If you are using K lite (especially at a weak rate like 1/10 tsp per gal) and add high carbonate potting amendments (like oyster shell) then you are setting yourself up for nitrogen deficiencies.

K lite nitrogen is nitrate based which is most efficiently used by plants in low alkalinity (low carbonate/bicarbonate) systems. As you increase the root zone alkalinity plants would like to see more ammonia (as from urea).

What is the alkalinity of your irrigation water? Are you using RO or rain water? If you use tap water, that could already supply enough bicarbonate to require ammonia/urea before the addition of calcareous pot amendments.

 

[Rick]

I think you have done a number of things that are combining to cause the issue:


►Excessive calcium can interfere with magnesium uptake. Powders have a lot of surface area, after all, so maybe the oyster shell powder is interfering chemically, as well as physically.


►I think Stone's suggestion is a good "quick fix", but if you supplement with urea, use it as a foliar spray, and it's not as well absorbed through the roots.

Both of the above are good points. Calcium/magnesium balance, and oyster shell is a phosphate absorber too. Not to mention all the alkalinity problems introduced with oyster shell and your tap water. By adding the oyster shell you essentially negate the dilution of your tap water.

You can feed K lite at low doses as you describe on a daily basis, and it would work well, but you need to start out with more dilute irrigation water and no calcareous pot amendments.

 

[Silvan]

I was just wondering what was the temperature in your growing area ?
I grow my parvis outside for the summer and around october when the temperature shifts, if I wait too long to bring them inside they shed some leaves... maybe if your plants were expose to a draft or cooler temperature that would have cause some leaves to yellow..