Disa fertilizer

[gdupont]

Hi, all. I have a Disa tripetaloides and am wondering about fertilizers. Everyone always says that you need to use extremely low levels, but I would appreciate a more specific measurement. I have Dyna-Gro Liquid Grow Plant Food 7-9-5, which I believe is supposed to be good for Phrags. On the back it says, "indoor plants mix 1/4 to 1/2 tsp of Liquid Grow to each gallon of water every time you water." How should I be scaling this for Disas? Thanks.

 

[naoki]

Walter Orchard (2013, Orchid Digest, July, Aug, Sept issue, 2013, p. 124-130) recommends 100-200ppm TDS (100ppm is preferable). I think he grows on flow table, though. Wodrich (1999) indicated that there was no problem up to 600 micro S/cm (about 300ppm), and plant size increased with higher concentration. But they seem to flower too early and die. Piennar's (2005) thesis tried up to 1110 microS/cm (about 555ppm) with Ebb-flow or Drip irrigation. Higher fertilization produced bigger plants in some cases, but the plants produce less roots as expected. Although it wasn't statistically significant, it was concerning that plants with high fertilization could potentially have smaller tubers for the next year. So I think that it is safer to be at the low end as Orchard recommended. Also, how you grow them will influence the best concentration, too. Those studies use hydroponics, so fluctuation in EC is buffered. With manual irrigation, the media may become drier (higher EC around the roots), so you may need to reduce the concentration. I think Orchard uses sphag based media while Piennar used silica sand (no CEC). So it is likely that with low CEC media like Piennar, Disa can handle higher EC.

 

[Stone]

Disas also seem to prefer ammonium over nitrate.

 

[gdupont]

Walter Orchard (2013, Orchid Digest, July, Aug, Sept issue, 2013, p. 124-130) recommends 100-200ppm TDS (100ppm is preferable). I think he grows on flow table, though. Wodrich (1999) indicated that there was no problem up to 600 micro S/cm (about 300ppm), and plant size increased with higher concentration. But they seem to flower too early and die. Piennar's (2005) thesis tried up to 1110 microS/cm (about 555ppm) with Ebb-flow or Drip irrigation. Higher fertilization produced bigger plants in some cases, but the plants produce less roots as expected. Although it wasn't statistically significant, it was concerning that plants with high fertilization could potentially have smaller tubers for the next year. So I think that it is safer to be at the low end as Orchard recommended. Also, how you grow them will influence the best concentration, too. Those studies use hydroponics, so fluctuation in EC is buffered. With manual irrigation, the media may become drier (higher EC around the roots), so you may need to reduce the concentration. I think Orchard uses sphag based media while Piennar used silica sand (no CEC). So it is likely that with low CEC media like Piennar, Disa can handle higher EC.

Thanks so much for this! Here's how I grow my Disa:

Disa Growing Method Illustration

Do you have any fertilizers that you would recommend in particular? Would Dyna Gro grow be ok, and if so, any idea at what dose? Thanks!