Low salt fertilizer

[buffalo]

I thought bottled fertilizer all had salt (sulfates). What exactly would be a low salt fertilizer for orchids? Do anyone make there own fertilizer for orchids or fertilizer substitute?

[tucker85]

Almost all nutrient elements in a fertilizer exist as salts. Sulfates are just one type of salt and sulfates often make up only a tiny percentage of the fertilizer. When growers talk about the problem of fertilizer salts building up in the media, they're referring to any fertilizer nutrients that are provided in too large a quantity for the orchids roots to absorb. Those nutrients can accumulate in the mix and burn the roots and cause other problems. Two techniques used to prevent that the accumulation of fertilizer salts is to flush the media regularly with plain water and to use a weak fertilizer concentration.

[estación seca]

It's a lot of trouble to buy individual components, weigh them on a scale that costs a lot of money to buy, grind them to a uniform shape, mix them well, and store them properly. Most people find it much easier to buy premixed water-soluble fertilizer.

[buffalo]

Originally Posted by tucker85

Almost all nutrient elements in a fertilizer exist as salts. Sulfates are just one type of salt and sulfates often make up only a tiny percentage of the fertilizer. When growers talk about the problem of fertilizer salts building up in the media, they're referring to any fertilizer nutrients that are provided in too large a quantity for the orchids roots to absorb. Those nutrients can accumulate in the mix and burn the roots and cause other problems. Two techniques used to prevent that the accumulation of fertilizer salts is to flush the media regularly with plain water and to use a weak fertilizer concentration.

Whats considered a weak solution? Should we fertilize with fertilizers that have small numbers like 5 5 5 or just go with 20 20 20 at say 1/4 strength which would be better?

[estación seca]

Originally Posted by buffalo

Whats considered a weak solution? Should we fertilize with fertilizers that have small numbers like 5 5 5 or just go with 20 20 20 at say 1/4 strength which would be better?

Great information here:

First Rays - Fertilizing

including a detailed discussion of exactly your questions.

[bil]

Originally Posted by estación seca

Great information here:

First Rays - Fertilizing

including a detailed discussion of exactly your questions.

´
Spot on.

[naoki]

Ray's web site has lots of good info as Estación pointed out.

For the original question: if you adjust the ratio of the macro nutrients, you can get lower total salt fertilizer. We don't quite fully understand epiphyte nutrients (so we don't know what would be a good ratio of minerals), but reducing TDS by removing excess, unneeded or harmful mineral nutrients should be beneficial somewhat. Lower TDS means that easier water uptake by roots. For example, compared with 20-20-20, MSU has reduced P. The reduced P seems to be ok, and also there are some evidence that the excess of P inhibits the mycorrhizae association (yes, it can occur in pots). Reducing K is a bit controversial, and there isn't strong evidence. But there are evidences showing epiphytes are really efficient at recycling K. I am not quite convinced that K interferes with other nutrient uptake (at the rate we fertilize), but K-Lite can be beneficial in reducing the TDS if plants don't need a lot of K because of its efficient recycling. So maybe you are thinking these as reduced salt fertilizers?

There are lots of opinions, but 20-60ppm of N seems to be the safe starting point if you fertilize frequently. With 20-20-20, this means about 1/10 to 1/4tsp per gallon. With 5-5-5, 1/3-1tsp per gallon.

I keep changing, but I'm going with 30ppm N (about once a week) at this moment.

20-20-20 and 5-5-5 is practically same, just one is more diluted, so you adjust the amount you put in the water.

Just for your info, "1/4 strength" doesn't mean anything in fertilizer because we don't know what would be "1 strength" (different for different brand). I'm guess that you probably mean 1/4 tsp per gallon, but people can't be sure about it.