Tomato food

FC - Yes, pretty well. The important thing is that the cheapest is a water soluble solid. The liquid ones are a lot more expensive because you are mainly paying for the water. What is exactly cheapest depends on what size pack you buy and how much you pay.

Its very easy to calculate. Below I have put a table of three high potassium products that came up on a quick Google. The columns are name, pack weight, pack cost and the NPK ratio, which will be on the side of the package.

Name .................weight ....price.... %N ....%P ...%K ...grams of K ...pence per gram
Chempak4 ..........800........ 8.99 .....15 ......15 .....30..... 240 ..............26.7 ...3.75
Chempak tomato. 1000 ......5.99 ......11 .......9 .....30 ......300 .............50.1 ... 2.00
Phostrogen ..........1200 ......5.99 ......14 .......10 ....27 .....324 .............54.1 ... 1.85
My apologies - Scrungee is quite correct - I called it pence per gram, then showed the number of grams you get for £1.00. The amended figures are in red.

The important columns are the last two.

Grams of K (ie potassium) is simply the weight of the pack times the percentage of it that is potassium.

The pence per gram of K is the number of grams of K in the pack divided into the cost of the pack.

I have ranked these on the cost of just the K alone. You could also do it on the cost the three elements combined. Phostrogen has a bit more N and P.

On this table there is nothing between the last two, but it will depend on the price you pay. If you can find a Wilko high potassium product - that could be the cheapest of them all.

Sorry about all the dots, but its difficult to show a table, as the software removes all the spaces.

And Yes, I would use the same for plants when they are flowering. Earlier in the year when they haven't started to flower I use a more balanced feed - MiracleGrow

 

@PeterS are you sure about those calcs because I make it something very different? (without going into complicated chemistry).



(EDIT: table above subsequently edited by PeterS "My apologies - Scrungee is quite correct - I called it pence per gram, then showed the number of grams you get for £1.00. The amended figures are in red." - Thanks for that Peter)


Moving on to a comparison with Wilkos 1L liquid tomato feed - It's NPK (Nitrogen/Phosphorus/Potassium) 5-6-10, so assuming those percentages are w/w, and that 'concentrate' solution has an SG of 1.000, then it contains 100g (10% x 1Kg) of Potassium, and as it currently costs £2 for a litre bottle, that's 100g for £2, so 2p/g of K, but I always/only buy mine when it's reduced, such as these 800ml bottles reduced to 10p, getting my expenditure down to 1/8th of a penny for 1g of Potassium

 

Good old chicken pellets for me,liquid feed 1 measure to 1 gall watering can well stirred or a hand full scattered round the plant's and watered in.I have used this way now for a number of years with good result's

 

Came 3 rd in the biggest tomato competition last year. Fed on Tomorite - nothing else,
Jenny

 

Yes Scrungee - you are absolutely right. My apologies. I was in a bit of a rush as I was already 10 minutes late for something. What I showed of course, was the number of grams you get for £1. But then described it as the cost per gram. I had already convinced myself that Phostrogen was the best value (fractionally), but the figures didn't appear to support that.

I did a table several years ago - using a similar analysis, but can't find it now - I think it has been wiped. Tomorite, as a liquid, came out a lot more expensive than the solid feeds, so its nice to see Wilkos is so cheap. I think they also do a solid high potassium feed, which could be even cheaper still - but as you have pointed out, it all depends on getting it for a good price.

I often use Miraclegrow, which is pretty cheap, early in the season and then later on add pure Potassium Sulphate to it to raise the Potassium level. Bowers Potassium Sulphate is about 1.00 p/gram - even cheaper.

The message is you can calculate what is cheapest - but if you are only using a small amount it doesn't matter too much. However I have over 30 Brugmansia and they need feeding almost every day.

 

Just as a follow up. Last year at the Harrogate Flower Show, I had a long conversation on several subjects with a delegate on a technical help desk. I had met him before and knew that he was a technical adviser to the Tomato Growers Association.

I asked him whether the more expensive tomato feeds offered anything different from the cheapest. He said no - there was no difference between them other than the percentages of the three main chemicals. He also said that they contained exactly the same trace elements. Consequently the cheapest was just as good as the most expensive.

 

Yep,
works out @ £1.23 per slice.....

 

FC - excellent. I like to work on grams, as I am never sure if all companies use the same dilution rate - so I ignore what they say about how many litres it makes.

 

@PeterS , etc. Calculate in a spreadsheet, add table borders, copy (snipping tool or PrintScr), paste into Paint (etc.), crop, resize (if required), upload and you'll have a table as in post #3 above.

g/£ is a good the best way to calculate, it's the way I work with everything, cost/m/m²/m³, etc.

 

Scrungee - thank you very much for the computer info. I will have a go at that. I simply copied a range and pasted it. In draft it looked perfect - but when posted it screwed it all up.