Hi Carol,

Are you feeding them, and if so with what? A balanced fertilizer, i.e. equal amounts of N-P-K (Nitrogen-Phosphorus-Potassium), is a good all-round fertilizer.

The problem could be that they are getting too much Nitrogen. A high Nitrogen fertilizer can cause lots of leaf and stem growth which can be detrimental to flower growth.

I would feed them with a fertilizer with a higher Phosphorus content as this will promote flower production and see how they go.

Myron.

Myron did you mean Potassium?

Sorry Steragram, phosphorus primarily influences roots, flowers, and fruits. From what I understand potassium is important for overall plant health, but doesn't contribute directly to flower/fruit production.

I've had the same argument about potassium stimulating flower growth before, and I've even heard that The RHS says this. Some time ago I did a bit of research. I'm now satisfied that this isn't the case and it's phosphorus that is important for flower growth.

The old maxim is "Potash for petals"
Potash being the old name for potassium.
I add my own "phos-for-roots and that leaves nitrogen"

Well you're entitled to your personal opinion Myron, but potassium is more important for flowering than phosphorus - as Urbanite says, phosphorus is more important for roots. But all three (nitrogen, potassium, phosphorus) are critical to plant growth for other reasons, including cell structure of the entire plant.

Tomato food, which we all use for flowers as well as tomatoes is high potash Myron - strange if they are wrong after all these years. Would be interested in your research.

Hi, welcome to GoY, when you planted your bare root plants, did you plant them vertically, or horizontally, if the former they take a while to establish, they prefer to be planted horizontally, so you can either dig them up when they die back in autumn, or leave them, they will establish eventually, the choice is yours, Derek.

Well, I always thought that potassium was the fertilizer for flower growth too. That is until I searched the web and found lots of conflicting information. Some say that that potassium helps flower and fruit growth and others say it's phosphorus.

Do an internet search and have look at various web sites and you will see what I mean. It's very confusing.

I see what you are saying. The advice is usually to start feeding eg tomatoes with potash when the first flowers have formed because it doesn't make flowers form but enables better transfer of water an nutrients to them. Until then they need the balanced NPK.

But I always give my gooseberries a high potash feed in late February and I get bumper crops. Difficult isn't it?

This is the answer I gave to a fertiliser question in March...

"Basic ingredients are N-P-K

N Nitrogen helps the plant build protein. Plants will take up nitrogen at the expense of other elements. Too much nitrogen will lead to foliage rather than flowers. High nitrogen fertiliser is used for lawns.

P Phosphorous is needed for good root and shoot growth.

K Potassium is used for general vigour. It regulates the movement of water and food within the plant and encourages fruit development.

Plants also need traces of other elements particularly:
magnesium to help make chlorophyll - the 'green stuff' needed to process sunlight.
Calcium builds cell membranes (the equivalent of our bones)"

The problem with saying that one element does this and another does that is that plants need a mixture of elements throughout the year - and they will suffer if they are starved of any. It may be that if phosphorous has been in short supply in the soil then using a high phos feed will give the appearance of giving better flowers simply because it is helping the plant to grow - although many plants set seed as a sign of stress, very few plants will flower if they are not healthy to start off.

There's a nice, simple explanation of NPK at http://eartheasy.com/soil-test-kit (there are similar kits available in UK and EU)

Thanks, that makes more sense now that you have explained it that way.