Fertilizer numbers

Hi Geoff,
Graeme is right about the elements, and N is for top growth, P of roots, and K for flowers and fruit growth. The figures are the percentage of each nutrient, so you are right in that those with the higher numbers are usually the most concentrated

At this time of year a balanced fertilizer is great as that will make the plants grow, - growmore has a 7:7:7 ratio.
When you are planting in the autumn, Bonemeal is great as it's 3.5:20:0 ratio helps the roots. In high summer, particularly for perennial/ bedding borders, or for tomatoes, then something like tomorite has a 7:7:17 ratio.

Don't be tempted to use a stronger one, for better results, some plants will like some fertilisers, others will prefer a different mix, - and always ask if the customer wants organic or not, - it's a bit too late when you've used a chemical to find they want an organic alternatice

Interesting................... I wasn't suggesting just putting on the strongest one you can get hold of though!!...... thought that if you used some that was twice as strong, you could just use half the volume with the same overall effect?

niall gibb said:

hi, it certainly would not make economic sense to use the strongest one. This would result in a real flush of growth, which would be soft and require more cutting!

I would advise you read up on NPK and get a basic understanding. Also a soil sample will advise what nutrients are required. As phosphorus levels do not normally need to be raised.

Fertiliser companies do not have to declare any percentages below 4% so say a 8:0:0 can still have 3% phosphorus and 3% potash, which inturn means if you double up products you are increasing these levels.

Also there is interesting research into phosphites v phosphates for uptake and good root hairs for healthly plants.

I wonder how many maintenance companies get soil samples done for customers, and provide a nutrient programme based on this...... just a thought

Replies

Graeme @ BGS April 5, 2010 at 8:33pm

Hope not teaching you to such eggs....

NPK represents the key chemical elements Nitrogen (N), Phosphorus (P) and Potassium (K), these values will help you to identify the best fertiliser for a particular problem / job. For example the higher the N rate will promote leafy top growth of the grass.

If unsure then opt for a balance fertiliser where the NPK are in equal measures and reflected so in the ratio such as 3.3.3

In your examples given, yes you are basically correct about the value of the given element being double etc. However if should always check the doseage rate on your fertiliser and follow their recommended application rate.
Claire Brown April 7, 2010 at 4:10pm

Hi Geoff,
Graeme is right about the elements, and N is for top growth, P of roots, and K for flowers and fruit growth. The figures are the percentage of each nutrient, so you are right in that those with the higher numbers are usually the most concentrated

At this time of year a balanced fertilizer is great as that will make the plants grow, - growmore has a 7:7:7 ratio.
When you are planting in the autumn, Bonemeal is great as it's 3.5:20:0 ratio helps the roots. In high summer, particularly for perennial/ bedding borders, or for tomatoes, then something like tomorite has a 7:7:17 ratio.

Don't be tempted to use a stronger one, for better results, some plants will like some fertilisers, others will prefer a different mix, - and always ask if the customer wants organic or not, - it's a bit too late when you've used a chemical to find they want an organic alternatice
Geoff Norfolk April 8, 2010 at 12:14pm

Interesting................... I wasn't suggesting just putting on the strongest one you can get hold of though!!...... thought that if you used some that was twice as strong, you could just use half the volume with the same overall effect?

niall gibb said:
hi, it certainly would not make economic sense to use the strongest one. This would result in a real flush of growth, which would be soft and require more cutting!

I would advise you read up on NPK and get a basic understanding. Also a soil sample will advise what nutrients are required. As phosphorus levels do not normally need to be raised.

Fertiliser companies do not have to declare any percentages below 4% so say a 8:0:0 can still have 3% phosphorus and 3% potash, which inturn means if you double up products you are increasing these levels.

Also there is interesting research into phosphites v phosphates for uptake and good root hairs for healthly plants.

I wonder how many maintenance companies get soil samples done for customers, and provide a nutrient programme based on this...... just a thought