Fertilizing Plants/Shrubs

Good Morning all,
Hubby and I have been busy since the beginning of March planting many new evergreen shrubs and trees. We ammended the soil, raised beds, mulched and watered. Now I am wondering about the best type of fertilizer to use. The recent issue of Geogia Gardening Magazine has an article on fertilizing plants. The author recommends a 16-4-8 fertilizer for March, May and September. George Reeves recommends 10-10-10, in March or April and then switching over to a 15-3-15 fertilizer in May and June. I'll be honest, I am at a lost as to what the numbers mean and with the big investment we have made in new plantings, I very much want to do the best thing to ensure a heatlhy landscape.
Thanks for any advice you can give.

This is a really big question with answers that will go in all directions! Soil testing, what ratio fertilizer, organic, micro-nutrients, some newly planted shrubs don't get extra fertilizer their first year... It is - or can be - a confusing topic!

I'll watch this spot to see how the others vote, but I am currently working 10-10-10 (equal amounts of (nitrogen, phosphorus, and potassium) into the top layer of soil around the plants. Except for the peonies where I use Kow Power composted manure.

Wikipedia has a lot of solid info at http://en.wikipedia.org/wiki/Fertilizer which will explain the numbers and a lot more.

Sterling in Atlanta (Dunwoody)

10 10 10 is an all around safe number fertiziler. i use stay green from loxwes ita a thre month slow release and then during the spring and summer i also add miracle grow water fert once a week. some plants i use the water soulable more. but all my stuff gets the 3 month slow release.

all my plants get it once planted.

Thanks. I think that 10-10-10 is the way to go -seems to be the best all purpose fertilizer. Do you do anything different for camillas and azaleas? Maybe some organic compost spread around the plants that flower?

Here's a question:
what is the difference between 10-10-10 and 3-3-3? Now don't say that the first has a higher percentage of ingredients. I know that part. But all-in-all - why would you buy a 3-3-3? Wouldn't you have to use more of it to get the same effect? Same with 20-20-20, you'd just use less. So why the option of the same balance in different concentrations?

Gliz,

re azaleas/camellias.......about mid. Feb. I feed with food especially for azaleas/camellias, then top dress with manure, compost or both. Some will say you should only feed after flowering but I feed then also. Mine have been beautiful ever since I started this pre-feeding and top-dressing routine........about four years now.

Thanks bugme for the azalea/camilla advice. Once you have a proven routine, stick with it.
Sterling, my head is spinning. Is it not so much the amount that is applied as to the frequency of application?

I hope you get the corect answer to that one sterhill,I've been wondering about that question,for over 40 years.I know the first is Nitrogen,the2nd,is potassium,and last potash,but the analisis has blown my mind,with the precentages.I know you get stronger roots with 0-15-15,2-12-12 is a good orchard fert analisis,but for the garden,you can't go wrong with 10-10-10.I hope to see some concrete results.Mike

OK - here is what I know:
The three numbers are the three primary ingredients of nitrogen (N), phosphorus (P) and potassium/potash (K). Walter Reeves says you can remember it by the mantra: Up, Down, All Around.

"In simple terms, the first number on a fertilizer bag promotes the growth of leaves (UP), the second number promotes roots (DOWN) and the third number promotes resistance to stress (ALL AROUND)"

Now - sorry but that still leaves me a bit confused...

(N)-Nitrogen: he goes on to say that for lawns you want a high first number like 16-4-8 to feed the intense upward growth of grass. I guess trees and non-flowering shrubs fall into this catagory.

(P)-phosphorus "6-8-8 or 18-29-6 work well as root-stimulating fertilizers. An additional benefit of a fertilizer having a high middle number is that flowering and seed production are also increased."

(K)-potassium/potash 22-3-16, etc contain a high amount of the last number: the nutrient Potassium. Keeps plants from being too stressed.

Sorry - I am still confused. Doesn't grass want to have good roots and not be stressed by intense summer heat? I guess the last two numbers in the 16-4-8 help with that.

So I use a 10-10-10 and figure that's a good compromise! Maybe a 10-15-10 would be better for bloomers but I start getting confused again.

Still don't know about the 10-10-10 vs the 3-3-3. I have asked two Master Gardeners I know and some other folks. Everyone wants to take off with the NPK explanation but then stops and realizes that was not the question. Scratches their head and says... dunno...

okay here is what i know and people always disagree but its the truth if you actually ask the manufacturers of fertilizer( which we have here.


the numbers are corect in what has said above but not the whole truth.

the numbers on the bag 3-3-3 (100 pound bag) are poundage numbers. there are 3 pounds each thing in the bag. 3 pounds nitrogen 3 phosphourous and 3 pounds potash. so in this example the bag has 3% of every ingredient by weight.

the numbers are actually called grade product numbers no wait i thinks its product grade numbers. oh shoot its one of those..

hubby is a construction worker so have to know this stuff. because in some cases of dirt they need less of one then the other to mix in the dirt to make it stable for asphalt and concrete or when they are growing new grasses they messed up doing a job.


so if you want more of one number then look for the highre number. its really just an amount of each in the bag percentage wise.

hope this is understanable. i hope., hehe Marie

the rest of the bag is filler stuff and things i really dont know.

Yes,the numbers represent the % of the NPK,and the rest of the 100% is "inert ingreatance".I went to the soil lab @ uga,just got too courious,but I have to confess,I still dunooo.I guess the fert. bag reprences 100%,10,is 10% N,10%Pand 10%K=30% useful stuff,and 70%,doesn't much matter,and I'll try not to worry about it,just except it.Now what is inert ingreatance,I'm worst than George.Mike

I do understand that the numbers indicate the percentage. The rest can be inert or micro nurtients. I'm good with that. But why - if you are looking for a balanced fert - would you choose 10-10-10 over 20-20-20 or 3-3-3?

They are similar in price so it would seem that you could use a smaller amount of the 20-20-20 to get the same effect as a 10-10-10. (?)

Sterling - It may be a good idea to email the UGA Agricultural and Environmental Services Lab with this question. Sounds like a great question for a final exam...

Great idea - I just sent them email! Will post when I have an answer.

here is the answer
***************************************************
The difference in the 1-1-1 ratio fertilizers is either 1. in the ingredients that are used to make the fertilizers or 2. in the amount of filler added to the fertilizer. In some cases, the filler used is pelleted finely ground limestone, and the amount used can vary. I am not sure of the specifics of why 10-10-10 vs 13-13-13 vs 17-17-17 are different, ie whether they are made from different materials or if they simply differ in the amount of filler. Differences in materials might be:

For N (the first number in the ratio), either ammonium nitrate, or urea, or ammonium sulfate are typically used and they differ in their N concentrations.

For P (the second number in the ratio), either normal superphosphate, triple superphosphate, diammonium phosphate, or monoammonium phosphate may be used, and they differ in their P concentrations. If the later two are used, they also supply some N which makes them more concentrated and therefore they could be used to make a more concentrated 1-1-1 ratioed fertilizer.

For K (the third number), potassium chloride is generally used but potassium sulfate is sometimes used. They too differ a bit in their K concentrations.

To answer why you would choose a 17-17-17 over a 10-10-10, I would do it on the basis of the cost of the nutrients contained within. The 17-17-17 contains 70% more nutrients than 10-10-10, but if it costs only 50% more, I would choose the 17-17-17 because you only need to add about 60% as much 17-17-17 to your plants to supply the same amount of nutrients as the 10-10-10.


David E. Kissel, Professor and Director
Agricultural and Environmental Services Laboratories
University of Georgia
dkissel@uga.edu

Thanks Sterling for following through with this. How lucky we are to have a great resource such as the UGA AES Lab. I will certainly carry this information with me the next time I go shopping for fertilizer.

Thank you sterhill,I see you have done your home work,and it is most informative.I grew up on a farm,have used fertilizers in many diferent aplications,mostly routinely,but never developed the love for plants,and the science of agriculture until I had been away from it for several years.What I mean by science is,the care and nurture of the plant,instead of stressing the land for the dollar.I find that vericulture is the best way to go,if you have the worm beds. Mike

This message was edited Mar 20, 2006 1:30 PM