When is fertilizer too much?

Ok, every publication and plant label seems to say something else, but in most cases they say "fertilize in spring and again in summer" or, occasionally, "apply fertilizer regularly during the growing and flowering season" - which sounds like more than twice a year...
On the other hand I remember my dad (who was more of a farmer than a gardener but used the technique on both the vegetables AND the flowers) taking out the horse once a week dragging a cart with a tank filled to the brim with horse and pig pee and gushing it over the beds as fertilizer. Regularly.

So I wonder, when is fertilizer too much? can you apply freely (as long as you don't take the bottle and spray it on the plants undiluted) or is there a point when the plants die of overfeeding? When I planted this spring, I threw some slow release fertilizer granules in the planting holes and used loads of compost, and every now and again I add some liquid fertilizer to the watering can. Is this already too much? The plants are so far looking ok (except the marguerites which look as if they are dead now, foliage at least, flowers are doing fine still!)

How do you experiences gardeners handle the fertilizing issue? I may have to add that our soil is very alkaline heavy clay, which can be rock hard in a dry spell but easily becomes a bit waterlogged when it rains too much at once...

 

Depends what plants you have, but for the record, i use loads, and I never have any problems. I use chicken pellets, lots in the spring and early summer and the the same but disolved in water for a weekly feed. The only thing i would say is, if you feed lush plants to excess they may grow beyond their ability to support themselves when it gets windy.

:D

 

Simply put, the fertilizer disolves into the water in the soil and increases the concentration of salts in it - not table salt but all kinds of salts. Increasing the concentration of nutrients obviously gives the plant more to feed on, but once the concentration gets to a certain point it is so strong that the plant cannot actually draw it in and the plant derives no benefit from it. If the concentration in the soil water goes beyond this point it can actually draw water OUT of the plant which will then appear to be dying of drought. This is rarely reached, but local concentrations in the ground (for example around fertilizer granules that weren't dug in properly) can cause local damage - usually called scorched roots in the gardening books.

So the answer is you can apply loads of fertilizer if there is sufficient water for it as there is in pig poo and pee etc, but not loads of concentrated fertilizers such as granular feeds, growmore etc.

Another point worth noting here is that with with the dry weather that is affecting some of us it is better to avoid applying fertilizers at all as they will make scarce soil water harder for the plant to extract. So save your money and time until the drought breaks.

 

Its a good question Wishaw. I usually only feed plants in pots. I use Miracle Grow and feed once every week, watering with a solution of one small scoop per pint of water as they recommend - but more often than they recommend. I also add Growmore sometimes and a slow release fertiliser. I don't seem to have any problems. As long as the feed is diluted I suspect that it is quite hard to overfeed - I have heard that said.

As far as the garden is concerned, I think that the feed value of manure is actually quite low. It is really added as a soil conditioner. But a good soil conditioner is perhaps more important than feed, especially on clay, which has a lot of nourishment in it.

 

Ok thanks for that - so once a week liquid fertilizer diluted in lots of water seems alright then. jazid, I believe you just answered my question regarding my marguerites - they looked poorly soon after planting, they grew and flowered, but the foliage turned yellow from the tips and further and further in. I now believe that the slow-release granules (Miracle Gro) I put into the planting holes are likely to blame, that they may have scorched the roots and that affects the foliage (and some of the flowers too, which die before they open, but not all of them, there still plenty of nice blooming going on too!).
Does anyone know, when I maybe dig up the marguerite bush and re-plant it in a new planting hole with no granules added, is it possible that it will recover? Worth trying? Or will it be alright next year if left in place and no more fertilizer added, to allow the granules to dissolve and get washed out? Maybe cut it back ti within a few inches of the ground and let it renew itself? I always thought marguerites are pretty much hard-wearing, but then again that could mean that they don't need any added fertilizer whatsoever in rich soil and it was simply too much...
On Sunday I get an outdoor tap and then I can use a watering hose! Finally! Dragging tens and twenties of watering cans across the garden at half past 4 in the morning is getting slightly to the "aaaaaargghhh!"-stage now!

 

I didn't know all this stuff! Thanks guys!