Fertiliser question

[Phil Wright]

Hello everyone,

I have a question about the rather dull subject of fertiliser.  In particular fertilising palms in containers.  Having done a little reading (and confused myself as much as clarified matters) I’ve tried to set out below the problem and what I believe is the answer.  If anyone can help I’ll happily summarise the responses so others can learn from this.

Many thanks,

Phil

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I’ve been growing palms in a greenhouse for a number of years now as well as gradually moving them outside and re-potting into large grow-bags as they mature.  They’re growing well but don’t seem to be growing at the pace they could be.  In the past we’ve used rotted bark as potting mix but have now switched to quality potting mix.  I’m also sure we’re not using the right fertiliser (it’s been recommended but I’m doubtful as to whether it’s right for palm trees).

The climate in northern NZ is maritime, warm-temperate (night/day16/24C in summer, 8/16C in winter, rare light frosts, damp and humid).  There are two groups of palms (all grown in grow-bags); young palms several years old in 2-15 litre bags, older palms in 40-120L bags.  The smaller palms are in an unheated greenhouse, the medium sized palms in a shade-house and larger ones outside with some or no protection depending upon the species.  The palms grow well (a little yellow in spring if exposed to frost) but don’t grow very fast.  Some of this may be due to water and being kept in small bags for too long (we’re resolving both of these problems) but I don’t feel they’re growing at an optimum speed.

We’ve recently switched from using rotted bark to using a quality potting mix with someone called CAN (Calcium ammonium nitrate).  We’re also using Yaramila Complex slow release during the growing season and recently started using Nitrosol liquid fertiliser on the leaves every few weeks.  Details on the two fertilisers below.

This is where I get stuck.  Fertilising seems to have many complex rules and exceptions to these rules.  I’m trying to find a general ‘one-size-fits-all’ solution (albeit with refinements for the age and location of the palm) that I can then improve on over time.

What I know so far has mostly been picked up from Timothy Broschat’s excellent book ‘Ornamental Palm Horticulture’...

·         High Nitrogen is required: ideally an NPK ratio of 3:1:2

·         Dolomite is needed to release Mg and Ca

·         Sulphate forms of Mn, Zn, Cu, and Fe are also required

·         Other trace elements required are B, Cl

·         It’s practically impossible for the amateur to figure out what trace elements are missing from a sick palm (symptoms of practically all deficiencies look the same to me) so best to ensure a good mix of trace elements.

 

The fertiliser we’re using is:

Yaramila Complex

·         NPK analysis 12-5-15

·         Nitrogen (N) 12.4%

·         of which nitrate N 4.9%

·         and ammonium N 7.4%

·         Phosphorus 5.2% (water-soluble P 65%)

·         Potassium 14.7%

·         Sulphur 8.0%

This seems to have the wrong NPK balance to me.

Nitrosol (liquid fertiliser)

“Designed as a total replacement, one-step fertiliser containing:

·         A balanced supply of the major nutrients N. P. and K. (8.3.6.) - all readily plant available to feed through BOTH the foliage and roots.

·         The organic matter from blood and bone includes amino acids, albumin, globulin, cholesterol, humates and protein, the building blocks of life.

·         A carefully balanced formulation of all the essential trace elements and minerals

·         Two naturally occurring growth promotants”

A better balance but I’m not sure we can rely upon this alone.  Also, it’s time-consuming to apply.

We’re also considering YaraBela CAN:

·         Nitrogen (N) 27%

·         of which nitrate N 13.5%

·         and ammonium N 13.5%

·         Magnesium 2.0%

·         Calcium 4.0%

·         Bulk density 1.04 kg per litre

No idea about this one but I’ve been told that many growers use high nitrogen fertiliser mixed with other things.

My question is relatively simple; if you were in my position, what one or two things would you do differently?  Or, put another way, what’s the one (or more than one!) thing I’m doing that just looks plain wring to you?  My guess is that Yaramila Complex isn’t right for palms but I’m happy to be corrected.

Thanks again.

Phil

 

[Hamal]

Hello Phil,

I am not sure that Yaramila Complex is completely wrong for palms. I have a very similar fertilizer with the following ingredients (slightly higher content, but about the same ratio):

16% N (of which is 9.7% nitrate and 6.3% ammonium)

8% P

22% K2O

3% MgO

and trace elements.

I add epsom salt, so in the end it contains a total of about 7% MgO (K:Mg ratio of 3:1) and also enough S.

In addition, I use organic N fertilizer (slow release), which I just sprinkle on the surface of the potted palms in March and June (that would be September and December for you). My substrate has excellent drainage (70-80% anorganic material), which means that some of fertilizer will probably not stay in the substrate, but that does not seem to matter. I feed and water my palms lavishly every two weeks during the growing season and about every four weeks during winter.

It is hard to say whether they achieve optimal growth, as Germany is not the optimal place to grow palms, but I am quite happy with my potted palms.

 

[edric]

Hi Phil, for potted container palms I use only Nitrosol (Green Ganic here) and a little Dolmite a cople times a year, Ed

[Phil Wright]

Thanks guys,

From what you say it sounds like I’m not doing anything too stupid.  Certainly it’s worth me continuing with the current fertiliser plus Nitrosol but it’s worth adding Dolomite twice a year – any idea of the quantities one should add based upon the volume of the pot?  I ask as the suppliers here will likely use it for pastures so I’m not sure they’ll be well placed to advise when it comes to palm trees!

Thanks again,

Phil

[peachy]

You can buy palm specific fertiliser but it is not cheap. (like I  am)  I use plain old chicken pellet fertiliser on the outside palms and indoors a weak mix of fish emulsion. A sprinkle of pre mixed trace elements twice a year and a monthly dose of liquid seaweed. Over the years I have tried everything but this formula seems to work quite well for a non scientific person like me.

[Phil Wright]

Thanks Peachy,

I'm going to look into using fish and/or seaweed based fertiliser.  Especially if we can make our own.

Ed, do you know the rough amount of dolomite you're using please?  I've read 7lbs/cubic yard which sounds rather excessive?

Thanks again,

Phil

 

[edric]

Hi Phil. about a quarter cup sprinkled around for the ones in ground, and a tablespoon per one gallon, for the potted ones, Ed

[Phil Wright]

11 hours ago, edric said:

Hi Phil. about a quarter cup sprinkled around for the ones in ground, and a tablespoon per one gallon, for the potted ones, Ed

Thanks Ed - very helpful.

Phil