Rule of thumb for blueberries - your nitrogen source should never be from nitrates. That will be fatal to your blueberries :-) You are correct, this would NOT be a good source. I would find a urea nitrogen source. EB Stone has a product for Fruits & Berries that will work just fine. Blueberries don't need a lot of fertilization, 10-20-10 is a good balance. I would check with your local county extension office to give you correct guidance for
your area. Here is a link to Purdue University's Fertilizing Blueberries. It's for Indiana, but will be helpful for you, too, I would think:

http://www.hort.purdue.edu/ext/HO-65.pdf

Patty S.

Here is a link that might be useful: Blueberry Council: How to Grow Blueberries

I think blueberries want more than chemicals anyway. Give them an organic fertilizer, even plantone or miracle gro organic if that's what you can find quick, topped with at least 3 inches of mulch. Without a surface mulch the plants will never be really happy. Sawdust or wood chips are great.

No, it will do no harm to your blueberries. The conversion to nitrate happens continuously in the soil, even with organic sources. I believe Osmocote is an ideal synthetic fertilizer for blueberries as the slow release assures you won't damage their shallow roots. I know that Carl Whitcomb recommends it for that purpose.

I agree that blueberries want more than "chemicals" if by that one means the chemicals supplied by your fertilizer. Blueberries thrive in soil high in organic matter. Mulch is extremely useful as is amending soil with compost and/or peat moss.

However you can supply the blueberries with either synthetic of natural fertilizer- the chemicals that the blueberries absorb will be the same in the end.

The reason ammonium fertilizers are recommended for blues is their slightly acidifying affect to soil. Blueberries like acid soil so it can be helpful. Some plants also are better at absorbing ammonium than nitrate which might be true of blues. Have to admit, I don't know about their ability to absorb nitrate- maybe a google researcher here can give you the final answer on that. Whitcomb could be wrong, the book I got his rec from is over 20 years old.

Thanks everyone..........I was doing some searching last night on youtube and ran across this interesting link on the use of osmoscote and blues. I thought it was interesting how he applied the product. If the link doesn't work, go to youtube and search on 'how to apply long term fertilizer to blueberries in pots'.

RM

Here is a link that might be useful: fertilizing blueberries

Well, everything I've ever read, all the seminars I've ever attended - and the seminars were presented by some of the most knowledgeable folks here in the State of California with growing blueberries commercially - have stressed nitrogen sources from ammonium sulfate or urea, not from nitrates. Dave Wilson Nursery also stresses 'no nitrogen from nitrates'. Not sure of Osmocote's nitrogen source, it sounds like it is derived from a nitrate, but perhaps because it is so slowly released that the plant and soil microorganisms will have a change to convert it so a form that is not toxic. The microorganism count with blueberries in pots will be lower than in the ground, even though mine are potted in 1/2 peat compost and 1/2 azealea mix, so for me, I'm not going to risk a fertilizer with nitrates. It is really hard to grow blueberries in the ground, although commercial growers here in California ha e developed a very successful method. For us home growers with limited space, growing in pots is the best alternative. I've included a link from Purdue's Extension (which is where I received my Master Gardener's certification), and below I've also included DWN's link on how to grow blueberries in containers, which is really helpful:

http://www.davewilson.com/homegrown/promotion/bluecontainer.html

U of Conn Extension says the same thing:
soiltest.uconn.edu/factsheets/FertPracBlueberry.pdf

West Virginia Univ. Extension, too:
http://www.wvu.edu/~agexten/hortcult/homegard/fertsmlft.htm

And here is the rationale from Cornell University, Dept of Ag Extension:

'Blueberries also have the unique ability to directly absorb the ammonium ion. Most plants absorb nitrate, which is then converted to ammonium by nitrate reductase, before incorporation into proteins. However, nitrate fertilizers can be detrimental to the blueberry. For this reason, ammonium forms of fertilizer are recommended, such as ammonium sulfate or urea. Ammonium sulfate is particularly good because it acidifies the soil, and most New York soils tend to have a pH higher than 4.5. Our soils are often underlaid with limestone, or the irrigation water source is neutral to basic. Furthermore, soils with clay slowly release potassium, a basic ion. These conditions tend to increase the pH over time, so even if the soil pH was reduced to 4.5 at planting, it can rise to unacceptable levels by the third or fourth year.'

http://www.fruit.cornell.edu/berry/production/blueberryproduction.htm

So for me, it's either ammonium sulfate or urea nitrogen sources to play it safe.

Patty S.

Here is a link that might be useful: Purdue U Extension: Fertilizing Blueberries

Patty, I believe Carl Whitcomb's advice was researched based. Can you lead me to any research that confirms the theory that nitrate based fertilizers are harmful to blues or that blues can't absorb N in the nitrate form?

That's not to say I'm not grateful for the links you've already listed here and I will read them to see if they contain what I'm asking you for. I just want to be sure that this isn't some kind of groupthink thing.

The common stated advice of these gurus that blueberries only thrive in a 4-5 pH makes me a little skeptical of other assertions. I've seen so many healthy and productive blueberries thriving in the low 6's.

It doesn't make any sense to me that nitrate in itself could be harmful to blues because ammonium is always in the process of being converted to nitrate and the blueberries can only absorb a certain amount before this happens.

I have used Osmocote in a similar form as the one the questioner mentions and it worked very well for me for years. I can't be sure that another formulation wouldn't have worked better, however.

I guess now others here can understand why I asked about osmocote and blueberries. About half the information I was able to find online says osmocote is safe (including the link I provided above) while the other half says to never use nitrogen in a nitrate form.

BTW, I wrote osmocote directly and they sent me a somewhat generic response that reads:

"Thank you for your interest in Scotts and for the opportunity to help you with your lawn and garden endeavors.Osmocote Outdoor & Indoor Plant Food is registered for use around blueberries. This product is specially formulated for the special needs of your vegetables and bedding plants. Osmocote Outdoor & Indoor Plant Food delivers the proper proportion of nutrients to help your plants thrive".

I'm glad we are discussing it.

RM

I found this on the internet from the University of Oregon and it appears even the research is still a bit murky but now that I've been looking around I see where Patty's opinion is coming from. I guess I'd save the Osmocote for something I know would benefit from it.

Ammonium-nitrogen vs. nitrate-nitrogen. Many studies
have been conducted regarding which form of nitrogen
blueberries prefer. Studies in hydroponics and sand (I
would call this semi-hydroponics) growing systems,
blueberry plants do take up both ammonium-nitrogen and
nitrate-nitrogen. However, in mineral soil production
systems (like in Oregon), blueberry plants that received
nitrate-nitrogen performed poorly compared to those
fertilized with ammonium-nitrogen. More recent studies
found that blueberry plants have limited nitrate reductase
activities, meaning the assimilation of nitrate in blueberry
plants could be limited. Therefore, blueberry plants
prefer the ammonium (NH4) form of nitrogen.

I'm pretty sure the blueberries could utilize the nitrate and I'm certain in the Osmocote form it wouldn't hurt them, but why not use what by blues would like the most. These days I just use my own urine which is one step from urea but with plenty of soluble P and K as well.

Thanks Patty, for your input. I learn something new on this site, well not everyday, but often enough.

Hmmm, interesting. Well, as an experiment I already gave two of my 20 plants the osmocote, I will let you know how they do............or don't do! lol.

thx.

RM

I have used Osmocote slow release for acid loving plants with good results. It is 9% N. 1.3% nitrate and 7.7% ammonium. Some nitrate must be OK.

Also, the Cornell extension statement that most plants can't absorb ammonium is either a misprint or mistaken (I suspect the former and should read urea instead of ammonium). I have read that some plants can absorb urea directly but can't remember which plants- maybe blueberries.

If most plants can't absorb ammonium, I vow not to make any more statements about soil chemistry without first rechecking my sources because it will mean that my memory has really gone further south than I thought. Urea is recommended as an N source for apples in wet cool soil because the trees can absorb the ammonium it becomes before it gets leached away. It's charge holds it to the soil. Nitrates are free spirits.

Out of curiousity I just looked and the slow release fertilizer that Dave is having so much luck with (Florikan Nutricote) has half it's nitrogen source in a nitrate form also.

7.45% Nitrate Nitrogen
6.9% Ammonical Nitrogen

RM

Hman,

The use of urine as a fertilizer been has been presented on the forum several times in the past. I know blueberries are sensitive to sodium/salt... Is there any concern in using urine as a fertilizer because of salts? Hard to find good info on this.

"Posted by riverman1 (My Page) on Mon, Apr 18, 11 at 21:31

Out of curiousity I just looked and the slow release fertilizer that Dave is having so much luck with (Florikan Nutricote) has half it's nitrogen source in a nitrate form also.
7.45% Nitrate Nitrogen
6.9% Ammonical Nitrogen"

I'm glad someone else brought this up..I was sitting here dumbfounded on should I say or should I keep my mouth shut...lol...

Fruitnut,Harvestman, and myself have discussed all of this stuff in so much detail in the other posts that we should copyright it and have it published...lol...

Percentages and release times it what makes it safe or unsafe...Trust the 3 amigo's...lol...

Ammonium sulphate is the preferred source of nitrogen for blueberries when soil pH is above 4.0 . The sulphate helps keep the pH low. Ammonium sulphate is a common fertilizer and is cheaper to produce than nitrate fertilizers. So it is common in many fertilizers. Read the analysis. Urea is also ideal for blueberries but can volatilize in warmer weather.

I plan on using Scotts turf builder lawn fertilizer 30-0-4
Caution: make sure any lawn fertilizer you use does not contain herbicide, ie. weed N feed. I also plan on using a light application of a balanced fertilizer eg. 10-10-10 for additional P and K.

Turf Builder Analysis: 5.4% ammoniacal nitrogen, 19.8% urea nitrogen, * 6.3% other water soluble nitrogen.

Derived from *methyleneureas, urea, Potasium sulphate, ammonium sulphate, iron sucrate.

contains 5-7% slowly available methylenediurea nitrogen and dimethylenetriurea nitrogen.

soluble potash K2O, sulphur 7%, iron (water soluble 2%).

Nitrogen is the most important nutrient for blueberries of the NPK macros. Using a balanced 10-10-10 type exclusively will under supply N and oversupply the others. P is fairly stable (doesn't leach) and can become oversupplied. Excessive P can inhibit Fe uptake and lead to Fe deficiency.

If your water or soil has too much calcium, that can inhibit Magnesium. This can be alleviated with magnesium sulphate (epsom salts). Typical Mg deficiency causes a green Christmas tree pattern in the center of the leaf with chlorotic margins. Symptoms often start with basal leaves.

Finally pH is a measure of percent hydrogen. The amount of hydrogen itself is not directly important to the blueberry plant. However it affects the availability of important nutrients. So if all the nutrients are made available the pH can be higher than is typically recommended.

Using rain water gathered from gutters on your house can really help if you have well water with pH 7 and higher. I just tested the water in a pail I left out all winter and it was 5.0 (laboratory calibrated meter). Perfect for blueberry irrigation.

A 1/4" rain on a 2000 sq. ft. home will yield 310 gallons of water. I'd rather invest is a few rain barrels and gutters than mess around with acids, vinegar and pH meters for irrigation water.

Chloride is not tolerated well by blueberries. Therefore if you plan on using urine for fertilizer a low sodium diet might be in order. Probably would be healthier for you and the plants.

The deicing salt calcium chloride applied to highways in the winter near blueberry fields is a source of contention and a lawsuit against the road commission in Ottawa county MI. It can cause considerable crop damage.

The question about urine and salt is one I can only answer anecdotally in east coast conditions, where the salt has posed no problems for me in 20 years, even when used on shallow rooted vegetables. We usually get rain all growing season but sometimes get up to 2 months of drought.

I first got the idea of using it from my brother in law about 40 years ago- when we both lived in CA and he was using it.

Of course all available N is capable of burning roots if used in excess.

Check out blueberry plants grown using Osmocote vs 21-0-0.

Here is a link that might be useful: Osmocote vs 21-0-0

I'm with harvestman on the use of urine for fertilizer. If more people did this it would save large amounts of water and greatly decrease the amount of nitrogen in wastewater.

Urine is by and large sterile. However, it should be diluted and used quickly. Once it leaves the body it deteriorates quickly and takes on a strong foul odor. It can also be added to compost heaps for additional heat.

I ran across an old quote in a gardening book I read a few years ago.

"Throwe al about your apple trees on the roots thereof, the urine of old men, or of stale pisse long kept, they shall bring fruit much better" Leonard Mascall, 1592.

He is credited with introducing pippin apples to England. He is also the author of a book titled Of the arte an maner howe to plant and graffe all sortes of trees (1572).

Using urine as fertilizer has been successfully practiced or a long time, perhaps since antiquity.

I save mine all winter and can't see how this could be detrimental. In this state, I wouldn't think that N could volatize and I'm sure all the K and P would stay put.

Yes, urine will change over to ammonium which will increase the odor but if you put it out during rain no one will notice.

This is the second time someone has suggested the importance of freshness so maybe there's something I'm missing, such as it turning into nitrite. Until someone steers me to some clear info I'll run with what seems to work.

Fruitnut,

I'm curious, the osmocote you were using for acid loving plants, is this the same osmocote you were using on the plants in the pictures? You mentioned that the higher Nitrogen fertilizer did 20% better than the osmocote which left me wondering which osmocote...........just curious.

thx.

RM

RM:

I used 9-6-6 Osmocote on the one year blueberry growout. I won't consider the difference in growth significant. Both grew very well and perhaps I just didn't apply enough slow release or it wound down too soon. But I've used the 21-0-0 often and I've never damaged the plants at 1 tablespoon in 2-2.5 gallons water. I have burnt the plants applying 21-0-0 and watering it in.

I'd only use 21-0-0 if pH is above 4.5. Below that urea would be better because it doesn't lower pH , at least not as much.

The controlled release is easy to use and effective.

Elmer, maybe I should have said ammonia instead of ammonium, which might explain why urine should be fresh. I'll have to check my books to see if that would cause the N to volatize- even when applied during of just before rain.

I apoligize for hijacking the thread but I think we've answered the original question.

Thanks Fruitnut.....

I was reading an article published out of Texas last night and the author used cottonseed meal on his blueberries. Has anyone tried this?

Link pasted below.

RM

Here is a link that might be useful: fertilizing blueberries

Cottonseed is the usual organic fertilizer for blueberries- lots of N but not real quick release I guess...and it's acidic.

Funny though, I believe cotton growers tend to use very strong pesticides because they can- it's not a food crop. Surprised that wouldn't cause some pause.

I'm using cottonseed meal on my blueberries in half whiskey barrels. I'm also using urine, greensand, coffee grounds, leaf mulch and iron sulfate. I'm doing it organically, but I have yet to find the golden combo to get the kinds of results I see from Fruitnut or Dablaw. I suspect I'm just not watering enough, because I am indeed a water miser.

I like the idea of cottonseed meal for blueberries. I would think it would eliminate all chance of plant burn. I'm going to get some and give it a try. It should be good for all my potted trees.

Thanks for the idea.

Hey Fruitnut,

Doing some reading this evening on fertilizers and came across this thread. Did you ever try the cottonseed meal?

thx.

RM

DeGraandchamps blueberries in South Haven, Mi carried(s) an approx. analysis 19-7-7 slow release Osmocote product that was similarly formulated for slow-release throughout a 6 mo. period. I guess if you drench the soil with a higher concentration it could kill it. These -cote fertilizers don't tend to leach into the water table and are released through biological action, if I'm correct. They are prolly the greenest chems around.
I do think they respond well to kelp, though.
noogy

RM:

I tried bloodmeal and soon after had chlorosis. Perhaps not related but that, right or wrong, soured me on organic. So ever since it's been 21-0-0 or Osmocote for acid loving plants. I know they work.

For any other plant bloodmeal is converted to nitrate. Not good for blueberry. But it could be that the ammonium form factors in there somehow. Using ammonium sulfate I know it factors in, and lowers pH.

Thanks Fruitnut,

I found the recommedations of bob randall in the article I posted above interesting.

This summer I may try some cottonseed on a couple plants and see how they do. Like you I'm always concerned about ph and I know for sure ammonium sulf will drop ph so its hard to go away from it. I do wonder, however, if my plants are getting the full compliment of micronutrients while growing in mostly bark and peat and only using ammonium sulf.

RM

riverman,
I started using Jack's Classic Acid Special 17-6-6 for some cuttings from last summer.It has all the micros.They are pushing good growth with only about 1/4 teaspoon per gallon of water.The company also makes a 21-7-7 mix.The best price for 25# of that, that I could see with shipping is from A.M.Leonard. Brady

That looks like good stuff Brady, thanks for sharing. I couldn't find the acid classic on AM Leonard but did find it somewhere else. Here is a summary of the ingredients:

http://www.jrpeters.com/Products/Jack-s-Classic/Acid-Special.html

On the AM Leonard site,type in Jacks Acid in the search bar and it should bring up the 21-7-7.Brady