Zero or low nitrogen fertiliser

[Luke308]

Hi, I am starting to think about Autumn and its fertiliser requirements and I have to say I am having trouble deciding on the best path to take. Most books (northern hemisphere) refer to a 0.10.10 NPK ratio, but I have been unable to find something locally. I have come across "Canna PK 13 14" which is as it says 0.13.14, and it is used for hydroponics. Also I came across "Rapid bloom which is 0.50.30!!!" I think the rapid bloom is most likely over the top, but I am interested in hearing what others use for their low/zero nitrogen ferts? Has anyone tried the PK 13 14? I have been told the secret to strong healthy maples in Adelaide is a good fertiliser in Autumn to prepare it for its dormant period through winter. I would assume this applies to all deciduous trees?

So what are others using, where do you buy it and what are your results??
Thanks
Luke

[EdwardH]

Hi Luke, most of the info from the northern hemisphere relates to countries with cold winters...think ice, snow etc so they do not want any new growth on their trees as the freezing temps will kill it. Most parts of Australia do not have such issues so the zero nitrogen isn't really an issue here. You might want to get some feedback from members living in Canberra or western NSW etc who experience really cold winters.
I use normal ferts like osmocote, dynamic lifter, aquasole miraclegrow etc and have had good results on all my trees. I stop fertilizing in April and don't start again until August or September. My maples, pistachio, liquidambers and oaks all colour up well. They get better colour if they are kept on the dry side during autumn.
Hope this helps.

[shibui]

Luke, Read fertiliser ratios in conjunction with the application rates. The 0.50.30 you found will use a lower application rate than say 0.10.10. In the end the plant gets the same amount of stuff, theres just less 'filler' in the packet. Its about ratio rather than absolute numbers.

This subject has been discussed on this site before. I believe Grant Bowie (Canberra) responded then as Edward has this time - there appears to be no need to use 0 nitrogen ferts in Aust. I have always just reduced the amount of fert in autumn and put the high N fert back on the shelf and use something with lower N like 'for flowers and fruit, for that time of year.

[NBPCA]

Hi all,

We had our coldest winter for a while with a very big Minus 9 or so in the middle of it. This is very unusual for Canberra but will happen from time to time.

We had a problem with the Callistemon in that it would not stop growing into early winter and we lost about half of the potential flowers to the frost on the coldest day. The foliage however was not affected.

One other deciduous tree received some damage to the apex but has since recovered quite well.

We have no need to over winter the Bonsai as they have to do in Northern Europe but we are certainly colder than most parts of Australia and have a much shorter growing season.I do have to be carefull. We will start to taper off our fertilizing in March or so and be stopped by May; although the conifers could go on longer.

Grant

[AGarcia]

I agree that low N fertiliser during winter is okay, but if you are still keen for something with no Nitrogen, then it does exist.

I bought something called MKP (? - Mono potassium Phosphate?) or MPK. This is a 0-x-x soluble fertiliser that I use in Winter. I bought it from a Farming/produce store. Remember to keep it away from natives.

Regards

AG

[Luke308]

Thanks for everyone's replies, you have cleared up a misunderstanding for me. I now know that I don't need a zero nitrogen fert here in South Australia. I will have a look amongst my fert collection and see what has the lowest N rating for Autumn. I am growing mostly decidious trees at them moment, and assumed that being they go dormant they don't need nitrogen prior to winter. I was concerned about new growth not "hardening off" before the cold winter nights hit, I was partially right, but also wrong I will take Edward's advice and stop fertilising in April, and resume August, and that should keep my trees happy as a kid in a candy store

Thanks again guys and girls, maybe people could add to the name (brand and product) of fertiliser's they use during Autumn?

[Luke308]

I'd forget my head if it wasn't screwed on I forgot "Bretts" started a thread ages ago where I mentioned what I used last Autumn, and he recommended a similar PK 13 14. here is the link viewtopic.php?f=20&t=9115&start=0

Please forgive my forgetfulness

[shibui]

Remember Luke that the lowest N number does not necessarily mean the lowest N! its about ratios and application rates. eg 1:2:3 is higher N than 5:13:20 (just making up numbers at random, don't go looking for that fert).
A fert that has a N of 6 applied at 5ml per 10 litres potentially supplies twice as much N than a fert with N=15 applied at 1ml per 10 litres. (again just made up numbers to illustrate the point)

Comparing fertiliser applied as solids with those applied as liquid gets much more complicated however I have found that most trees appear to be self regulating and do not take up elements they do not need at the time so trees will still go dormant even when N is available. In this case, and with super heavy feeding, excess is wasted and leached out of the mix by watering but this also has potential to cause other problems - nutrification of waterways; excess N leaching through the soil profile is also held responsible for acidification of farmland(not sure of the effect in potting mix??)

The winter before last I pruned trident maples in the growing beds quite late and the new shoots carried leaves right through the winter with no apparent ill effect. Our winter nights mostly below 0, occasionally to -4 (have known -7 but not that winter) so its reasonably cool for Australia. From this experience it would seem to me that pruning is a far more important factor in preparing for winter than fertiliser.