liquid fertiliser for in-line fertiliser injector

[brammn]

I hope this is the right forum - if not can someone point me in the right directions please?!

I've bought a dosatron in line fertiliser unit to make feeding the orchids in my greenhouses easier.

Does anyone in the UK have one (or similar) and what do you recommend as the best liquid fertiliser for orchids? I've got some Vitax liquid orchid food, and it will work but it only seems to be available in half litre bottles which isn't a lot so I'm looking for recommendations of something I can buy in bulk...

Thanks

Nathan

[Ray]

Hi, Nathan.

When you purchase a liquid formula, you are mostly paying for water. Save yourself a bundle and make a liquid concentrate from powdered fertilizer.

Let's say you have a 12-5-10 fertilizer and want to use 25 ppm N at every watering. For that dose, the delivered liquid requires 0.19g/L. If your metering pump is set to give a 1:100 dilution, then your concentrate should simply be 100x 0.19, or 19g/L.

[brammn]

Unfortunately the unit won't take it - the manufacturer was very clear (I spoke to them) that it needs to be a liquid fertiliser. They said that trying to use a powder form and make a concentrate would mean lots of particles will stay in the solution and just clog it up.

I spoke to a local commercial nursery as well, they use a similar device and they reckon they always use liquid as well.

Thanks for the suggestion :-)

[Ray]

Hmmm. The manufacturer is apparently thinking of much greater concentrations. I have used a metering pump for over 25 years, and never had a clog.

Besides, what do they think a liquid fertilizer is? It is nothing more than a solution produced in a factory, instead of your home.

[brammn]

Thanks Ray - I spoke to the manufacturer and they said the problem with soluble is it doesn't dissolve properly and they said even with the filter some particles get through. The guy said he could show me photos of the inside of a unit that's been run for 6 months on a soluble powder and it will look wrecked vs a unit that;s been running for 3 years with liquid and it still looks brand new.

I've got hold of a load of cheap liquid fertiliser - the question now is about dilution. The package says its 7:7:7: (but in reality reading the P and the K are a bit lower than that - 3.1%P and 5.8%K) The instructions say 3.3 ml per 1 liter of water for normal garden/greenhouse plants. So thats 0.33% on the Dosatron, if I drop it down to 0.2 % will that be enough dilution? I used to water at 50% dilution with a powder standard garden fertiliser and it worked fine. Any thoughts/advice on this would be appreciated

Thanks

Nathan

[Ray]

How much fertilizer to use - or should I more correctly say, the concentration applied - should be determined based upon the feeding frequency.

When I metered fertilizer in my irrigation water, I typically watered 2 or 3 times a week, and I found 25 ppm N to be a good concentration. If you divide 2.3 by the %N in the fertilizer, the result is the ml/L for that level in the as-delivered irrigation solution. 2.3/7=0.33ml/L for your 7-7-7.

If your Dosatron is set for a 1:100 ratio, you should mix that liquid fertilizer with water in your feed tank so that it is 0.33x100=33ml/L.

If you only water once a week, you should probably consider a concentration in the 50-75 ppm N range, so double or triple that tank concentration.