[Kristen]

FWIW Doff have stockists on their web site

http://www.doff.co.uk/stockists.html

[sclarke624]

ta

[sssb]

hi kristen
the NPK listed on products is the ratio to each other. so 3 different products with NPK   1 1 2,     5 5 10,    and    50 50 100   will all be identical.  hope this makes sense

[Kristen]

hi kristen
the NPK listed on products is the ratio to each other. so 3 different products with NPK   1 1 2,     5 5 10,    and    50 50 100   will all be identical.  hope this makes sense

Thanks, I understand that, just wondered if it had any bearing on working out the cost ... just my befuddled brain I expect!

So I suppose all I need to do is take the costand divide that by the total diluted volume that a bottle can make - so I have a cost-per-litre of diluted feed (assuming that they can all be applied at the same rate / plant)

On that basis:

Suttons 900 litres for £6.95 = 0.77p / L

Tomorite 562 Litres  for £13.25 = 2.36p / L

Doff 1,162 Litres for £4.99 = 0.43p / L

If I've got that right it makes Tomorite look expensive - I've been using that for years

[sclarke624]

aha! I was waiting for you to do the maths.  Good job.

[Howard]

hi kristen
the NPK listed on products is the ratio to each other. so 3 different products with NPK   1 1 2,     5 5 10,    and    50 50 100   will all be identical.  hope this makes sense

It's not quite that simple.

Yes, the ratio between the three remains the same, but the actual amounts of Nitrogen, Phosphorus and Potassium alters.This is my take on it... those of a nervous disposition read no further - it'll probably make your eyes bleed!

I also make no claim that it is absolutely correct, but I think it is...  


The NPK figures don't give a true representation of the volume ratios of Nitrogen to Phosphorus to Potassium, for reasons dating way back (So I've read). The volume % of Nitrogen content is as read, however the volume % of Phosphorus is only 44% of the figure given and the volume % of Potassium is only 83% of the figure given.

So by volume, the three sets of figures are:

Suttons Tomato Superfeed - 10 : 4.40 : 19.92
Doff Tomato Feed             - 5 : 2.20 : 8.30
Tomorite                         - 4 : 1.98 : 6.64

If 750gm of Suttons makes 900l of feed, 0.83gm makes 1l.
If 2,500ml of Doff makes 1,162l of feed, 2.15ml makes 1l.
If 2,500ml of Tomorite makes 562l of feed, 4.45ml makes 1l.

For reference purposes we can assume 1gm to be equal to 1ml. So by my reckoning, in each litre of made food the volume % of Nitrogen, Phosphorus and Potassium is:

Suttons Tomato Superfeed - 0.083% : 0.037% : 0.165%
Doff Tomato Feed             - 0.107% : 0.047% : 0.178%
Tomorite                         - 0.178% : 0.088% : 0.295%

The Tomorite is clearly 'more concentrated' - it has about twice the content of the Suttons feed and a bit less over the Doff, so we can reasonably halve it's cost in comparison, but it's still the most expensive by a margin.

It's all I've ever used too...

[Kristen]

Sounds a bit like the toothpaste sellers increasing the diameter of the hole to sell more toothpaste ...

if the tomorite makes more concentrated feed, that's fine, but I'm still going to splosh about the same amount on each plant aren't I? (unless I am careful to measure the amount)

Plus I've just read on the Doff instructions "Growbags or Ring culture: use at double-strength" which levels the playing field rather ...

Full Doff instructions:

"In the greenhouse: when the first truss has set apply the feed every 7 days. 7 litres should be sufficient for 9 plants. Feed every 3-4 days when the second truss has set.

Outdoors: when the second truss has set apply the feed every 10-14 days. 7 litres should be sufficient for 12 plants

Growbags or Ring culture: use at double-strength and feed every 7 days

High performance recommendations: for higher yields the above rates can be applied twice as often - i.e. in the greenhouse, in grow bags, or ring culture, feed every 2-4 days; outdoor tomatoes can be fed every 5-7 days"

Tomorite says:

"Under glass: When first truss has set feed at alternate waterings

Outdoors : When second truss has set feed every 7-14 days. Use 4.5 litres for two plants.

Growbags: Use 4.5 litres per bag, feed once a week, under glass increase to twice a week when the second truss has set"

Personally I found that frequency too often last year - my Tomatoes were in 14" pots stood on soil, and the fruit split despite very even watering, and I think they were being over fed.

Source: http://www.wyevale.co.uk/Scotts-Levington-Tomorite-+1lt/0800000338,default,pd.html - select back of bottle and zoom in

[shaun]

just keep things simple i say 

[Ice]

 

I just buy the own brand stuff and feed with it once a week.  Might be more interested in exact ratios if I were a commercial grower, but I'm not, so I don't bother worrying.

[Kristen]

Well I got through two bottles of Tomorite last year - call that 26 quid. If one bottle of £4.99 Doff would do me instead (given that it makes twice as much as the Tomorite) that will work for me!

[Howard]

...if the tomorite makes more concentrated feed, that's fine, but I'm still going to splosh about the same amount on each plant aren't I? (unless I am careful to measure the amount)

Plus I've just read on the Doff instructions "Growbags or Ring culture: use at double-strength" which levels the playing field rather ...

Full Doff instructions:

"In the greenhouse: when the first truss has set apply the feed every 7 days. 7 litres should be sufficient for 9 plants. Feed every 3-4 days when the second truss has set.

Outdoors: when the second truss has set apply the feed every 10-14 days. 7 litres should be sufficient for 12 plants

Growbags or Ring culture: use at double-strength and feed every 7 days

High performance recommendations: for higher yields the above rates can be applied twice as often - i.e. in the greenhouse, in grow bags, or ring culture, feed every 2-4 days; outdoor tomatoes can be fed every 5-7 days"

Tomorite says:

"Under glass: When first truss has set feed at alternate waterings

Outdoors : When second truss has set feed every 7-14 days. Use 4.5 litres for two plants.

Growbags: Use 4.5 litres per bag, feed once a week, under glass increase to twice a week when the second truss has set"

If you take Doff's Growbag recommendations and double up the feed rate from 7l for nine plants to 14l, that's 4.6l per growbag - much the same as the Tomorite recommendation.

But that's still only half the 'dose' if you like - you would need to adopt Doff's 'High performance recommendations' to get somewhere close to similar doses.

But that would still only be £1.72/litre - 64p cheaper than Tomorite.

[Kristen]

Well its Doff for me this year ... I'll keep you posted

[peapod]

I buy wilkos if that helps?   

[DD.]

Back to University for me.

Never realised you needed a degree in mathematics & computer science to cultivate an allotment. My 33 year old electronics degree is not cutting the mustard, (we used punch cards to program computers).

I've survived so far by reading the back of packets of seed & labels on bottles, scribbling on bits of paper etc.. Evidentally we moved on!

[richyrich7]

just keep things simple i say 

Me too, I just splosh a bit in the can