I am going to be running about 50% ff happy frog mix, 30% coco, and 20% worm castings. When growing outside do i have to worry about salt build up in the coco when it gets dry or is there not enough coco in the mix to matter? I just know when growing in straight coco you have to keep it moist so salt doesnt build up.

Anybody? I know theirs something with coco bc my buddies have always told me to watch for build up when they grow in striaght coco.

coco needs to be flushed regularly because it builds up nutrient salts, have to flush it when it needs it, if the run off is stronger than what your putting in, then you got salt build up

I'm not sure at the percentages your using, but running coco with about 30% nutrient in it I find it helps to flush once a week. I started doing it with tap water, and then rinsed through the ph / nute but, after checking my run off after a ph / nute flush, I found it was miles too high, up near neutral. I'd only started flushing about half way through the flowering cycle and had been using drip emitters (which were allowing the media to dry out - now using drip rings, problem solved). I had to pound the pH back down with huge amounts of low pH water, a good amount of it was around pH 2. I'd think about it more in terms of media mass. Whenever you're growing in a pot, there's always a huge amount of material stored up in the media, a flush seems to freshen things up a lot. I'd flush. Make sure you use pH'ed water at least and check the run off. If they're outside and nearby, flushing should be easy. If the media dries out, the first lots of water through might not shift much because it needs to dissolve it out. It's best to flush once, then wait a few minutes and do it again. -like my reply, pls vote in my bulb poll (sig)-

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I flood my plants to flush them every week. Basically I put the hose on them for about 5 minutes to flush the coco, but I grow in coco only.

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[thanks for the reply fellas! I was going to use drippers this year to and i was afraid of them not watering every area that has coco, but im sure ill be alright. Like you said run clear ph'd water about once a week.

Don't bother with those stake type drippers, they're a pain in the ass. Sometimes they don't drip, the rates are hard to control and they only ever drip in one place, so the media won't be uniformly damp. When you pull them out to flush the container, the big stake hole will disappear and you can cut through other roots putting them back in. Go for drip rings, !loads! better. The guys that sell the drip emitters also do tiny clip on stakes for holding the thinner tubing. Make some rings with that (I used about 7 1.5mm holes) and prop them up with the clip on stakes (which you can poke into the coir at the sides of the pot, where you won't hit roots). I started out flushing with tap water thinking it'd be fine once I poured some low pH / nut feed through. Measuring the run off, it wasn't. The feed had done next to nothing to the pH, which was now near 7. Rinsing with tap water will raise the pH of the coir and it takes quite a lot of acidic rinsing to get it back down. If it's left high, the nutrient uptake will slow down. -like my reply? pls vote in my bulb poll (sig)-

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Everything is subject to salt build-up. Coco is no more or less susceptible, it's just that it has such a high potassium content that salt ratios get unbalanced, hence the need for a cal-mag supplement.

so high potassium can cause mg deficiency?

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I do believe K to be related to calcium, but in coco... it's the calcium and magnesium that are the first to show..... big cal-mag hog there. If it's only a 30% coi mix, you wouldn't need so much, but it's something to plan for, especially based on the quality of the coco. Tap water might be enough.