NPK For Troughs!

[G H Nelson]

Hi Crew/Gardeners
I've planted out some troughs with flowering plants...Sweet pea's and flowering climbers!
I have a mass of dry salts that I can use as fertilizers!

I would like to make up 2 litres of plant food....how many grams should I use of NPK!
Should I use MgSo4/Epsom salt/Trace as well?
Bearing in mind these a flowering plants in troughs!

I will be using Tapwater to make the plant feed up!
Cheers
hoggie

 

[dw1305]

Hi all,

Sweet pea's

You need to pinch the tops out on these when they are about 10cm tall (it doesn't matter if they are a bit taller, you can still take the top out), if you don't pinch them out they only form one stem and they don't flower for very long.

I would like to make up 2 litres of plant food....how many grams should I use of NPK!

I'd probably aim for about 100 ppm nitrogen, fed once a week.

If you start with KNO3, you need to work out the RMM. The RAM of potassium (K) is 39.1, nitrogen (N) = 14 and oxygen (O) = 16. which gives 39.1 + 14 + 48 = 101.1, which I'm going to round to 100, so KNO3 is 39% K and 14% N.

In one gram of KNO3 you have 0.14g of N, so 7.1g of KNO3 contains 1g of N. One gram = 1000 mg and ppm is equivalent to mg/l.

So ~7g of KNO3 in two litres of water is a 500 ppm solution, and 7g in ten litres of water is a 100 ppm liquid feed. Just make up ten litres and pour it all on.

This will also supply 280 ppm K (39.1/14 = 2.8).

Which phosphorus salt(S) do you have?

Should I use MgSo4/Epsom salt/Trace as well

Probably would for the magnesium, but only every other feed. Epsom salts are 10% Mg and you only need to feed about 20ppm Mg.

Trace elements should be fine with enough in the compost.

cheers Darrel

 

[G H Nelson]

Hi Darrel
Sweet peas lve already pinched them!
I've got the standard EI salts!
I've only got 5 small elongated troughs 40cm to 70cm!
So would like to do 25% feed out of a 2 litre container every few weeks!
Thanks for the information
Cheers hoggie

 

[dw1305]

Hi all,

I've got the standard EI salts!

I'd aim for 20ppm P, the extra potassium (K) won't matter.

I've only got 5 small elongated troughs 40cm to 70cm! So would like to do 25% feed out of a 2 litre container every few weeks!

I'd pour all 10 litres of the made up feed on when you water them, but it doesn't really matter.

I don't feed the pots, troughs and house plants in a systematic manner, I just give them a feed when they start to look a bit peaky.

cheers Darrel

 

[G H Nelson]

Cheers Darrel