Saving orchids but now have black root tips

[MAR8D08]

Hi everyone,

I'm new to the forum and new to taking care of orchids. I'm trying to save 2 phals that had been slowly dying since buying them 2 years ago. I realize now that I'd been under watering them. After repotting and appropriately watering, they've made a huge comeback in just under a month. Today I noticed that one of them has developed black tips on the little root nubbins that are trying to grow from his stalk. I'm not sure what to do now. Since they are doing so well, should I just continue how I've normally been taking care of them? Or should I intervene? Today I put a few milliliters of a (normal dilution) physan20 solution on the black nubbins.

Thanks for the help. Here's a link to the photos

https://www.flickr.com/gp/92380967@N07/333Xrd/

[WhiteRabbit]

Looks like it should be in a smaller pot, unless there's really a huge mass of roots.

Do you let the potting media become very nearly dry before watering?

[MAR8D08]

Yeah - - I knew the pot was pretty big. I filled the pot with rocks to reduce the ratio of moss to plant roots. And I let the potting media dry out pretty much all the way. Do you think I ought to repot again into a much smaller pot even though I used the rocks to fill up some space?

[WhiteRabbit]

I don't know if the pot size is the problem , it could be staying too wet in the center - how do you judge when to water?

[ALToronto]

Black root tips are usually a sign of chemical damage, such as over-fertilizing or using poor quality water. Use pure water with a very, very weak solution of high-N fertilizer, and you should see improvement in future roots. By very, very weak I mean about 1/50th of the label recommendation.

[MAR8D08]

thanks for your help guys - I went ahead and took a look at all the roots. Overall they looked pretty good, but the longest (and deepest in the potting media) on the big orchid was starting to get root rot. I trimmed away the rotten part and repotted with even more rocks so the roots were nice and snug. Is filtered water ok (from a brita filter)? Or should I be buying distilled. I read that distilled wasn't optimal b/c it lacks Mg.

[ALToronto]

You'd be surprised how little is filtered out by a Brita filter. It removes chlorine, and a very small proportion of minerals. I used it at first - out of the tap, water had 160-170 ppm total minerals. After one pass through a new Brita filter, it read 115-120. Still good quality, but I installed an RO system because Brita filters are so expensive per litre of water. I also use a fertilizer with Ca, Mg and other minerals (K-lite).

If you use more than 3 litres per day, an undercounter RO system will pay for itself in about a year.

[WhiteRabbit]

I just water with tap water - tho, of course quality of tap water varies by location.

If using pure water, add a free tablespoons of tap water to add minerals.