Spikes turn brown and shrivel

[khill]

I have had some successes and quite a few failures recently with my orchids. I have several plants of different genera that the spikes start great and then turn brown and shrivel.

What generally would cause this? Water quality? Not enough fertilizer? Temperature change? Pests? I'm at a loss. Now, I do grow outside in SW Florida so this time of year the humidity/temperature varies a bit.

Several of my dendrobiums (phal type) had a successful spike and then a failed spike. My Catt. Yellow Bird had only 1 successful spike (flower ended up looking kinda funny) and about 6-7 dried up and shrivelled. I currently have a phal spike that looks like its headed in the same dried up direction. Also one of my Vandas--same thing.

I am sure it is something I am doing, but not sure what. I don't fertilize constantly--maybe about 1-2 times a month with general orchid fertilizer. I try to water with RO or rainwater. Sometimes I have used our treated well water (salt), but only on a few occasions. I am starting to feel like a failure at this, but I have had some beautiful successes. It's the only thing that gives me hope. Any ideas?

[Ray]

I doubt that the natural environmental conditions would be an issue unless you get a real cold snap, so I'd be more inclined to think in terms of pests and/or your watering and feeding regimen.

• If your water supply is as brackish as some I've had the "pleasure" of experiencing down there, I would not use it at all.
• If you let the plants go too long between waterings, sometime that can lead to them aborting their spikes.
• As you do have an RO supply, I'd stick with that, but I hope you're aware that using a "normal" fertilizer in it will give you a solution with an extremely acidic pH, and that alone will be enough to do what you're observing.

What brand and formula of fertilizer do you use, and how much do you mix in a gallon of water?

I would recommend a fertilizer intended for pure water, and use it at a moderate concentration about three out of four waterings.

[khill]

Thank you Ray for your quick reply. No, I wasn't aware of the fertilizer issue with RO water. (I'm new at this whole orchid growing thing ).

I use Better-Gro Orchid Plus Water Soluble Orchid Food 20-14-13. I mix about 1 tbsp. per 2 gallons of water.

Now, what fertilizer would be recommended for RO water? And, if I am using rain water (in the summer), which then?

[Oldguypops]

I agree with Ray in that it sounds more chemical than environmental.
Stay away from "softened" water all together. That will poison your plants. The salts can stay in your growing media and hurt the plant for a long time.

Try using less fertilizer and more often. I use 1/2 teaspoon per gallon of water every time I water, and the plants are thriving.

Also, what kind of growing media are you using? Is it in good shape? If the plant is 'just hanging on', then it can't support the strain of flowering and will abort.

Good luck, and let us know how you resolve the problem.
Chris

[Undergrounder]

When my Masdevallia spikes browned and died it was from not being humid enough. I moved the lone survivor into a humidicrib and he's still going.

[khill]

Thank you. I'm guessing it's a fertilizer/water issue from all the replies. I will look into the correct fertilizer for RO water and go from there. Can anyone tell me--is that the MSU fertilizer that I hear many of your talk about?

[quiltergal]

At 1.5 tsp per gallon of water your ppm of N is 396. The recommended ppm is 125. You're burning them. Use Ray's Fert calculator in the link below. With N of 20 you only need .50 tsp/gal water, or 1 tsp/2gal.

GreenCare MSU has several formulations, one for RO or pure water and 1 for tap water. It's a great product.

Fertilizer PPM Calculator

[khill]

Thanks Terri--I'm going to order the pure water fertilizer for my RO and follow Ray's calculator.

At least I feel like I've gotten to the bottom of the problem with everyone's help. This orchidboard is the greatest!!!

[Ray]

With that particular fertilizer, I would use no more than 1/2 teaspoon per gallon, not 3 x that!

Rain water is pretty pure, so you'd use the same fertilizer as for RO.