Blueberry pH maintenance

The posts i have seen of folks who dont do much science or testing yet still have nice looking blueberry plants add woodchips. I have even asked local farms that grow them and they also add woodchips.

If you do a google search:
Do woodchips raise or lower pH…

You will get around a 50/50 answer. Lots of sites and studies that say that woodchips lower pH… also lots of sites and studies that say that woodchips do not lower pH.

Same for pine bark… anyone that says that it increases or decreases pH can be proved wrong or right by a simple google search.

Myself and one rare guy that grows cane fruits believe that its not so much the woodchips but the leaves that also get shredded and composted into the woodchips… which often leads to a fungal bomb… which in turn leads to a mycorrhizae relationship…which thrive in lower pH environments.

So my theory is… if you grow plants that thrive in lower pH situations… fungi is good.

The most common materials used in mulch are wood and bark chips, peat moss, pine straw, and even hay. All of these create an acidic substrate that fungi absolutely love.

1 Like

Wood chips tend to move the ph of soil toward neutral regardless of whether it is alkaline or acid. If your soil is ph 5.0 and you add wood chips, ph will tend to move up toward 6.5 or 7.0. Do the same in 8.0 ph soil and it will tend to move down toward 7.0. Pine needles and pine bark tend to slightly acidify the soil. Pine trees thrive in acidic soil because they can best absorb nutrients. It makes sense that they have mechanisms to acidify the soil over time. All this proves is that there are a lot of websites that don’t have good information. As I stated above, wood chips, pine bark, pine needles, and similar materials all contain large amounts of cellulose which is broken down by soil microorganisms. They require nitrogen in the process. This is why wood chips can improve the soil, but also can create problems with plants growing in that soil. Use wood chips as mulch and the soil surface layer will be depleted of nitrogen in a few months. Work the wood chips into the soil and all of the tilled soil will be depleted of nitrogen until such time as the wood chips are completely broken down. I’ve seen this first hand too many times. A gardener friend got a large load of wood chips placed at the end of his garden. He wondered why corn would not grow near the wood chips. I laughed and asked if he added any nitrogen. “no, should I?” was his response. I told him to get some ammonium nitrate and put down 3 pounds per 100 square feet where the wood chips were on and in the soil. His corn then produced a crop.

Not sure depleted is the correct term… this study of woodchips in orchards says that N is ‘immobilized’ and is ‘temporary’.
It goes on to say that as they break down they ‘return’ N and other elements to the soil.

I can also provide links saying what you are saying… as well as saying its a myth altogether that woodchips ‘remove’ N from the soil.

So the internet isnt reliable at all in coming to any kind of conclusion.

If anyone is on the blackberry growers group a fellow by the name of Jim Elliot from Arkansas did some nice videos on plants that he planted in a row at the same time. He added woodchips heavy to some plants and none to the others. The plants that received the woodchips grew substantially more and faster than the ones without.

Even though science can likely prove that this is wrong… it works. And i too add woodchips to all of my cane fruits, strawberries, garlic and things that i want to grow… I am new to blueberries but will likely do the same and just add woodchips to top dress… like the local U-Pick does with success.

Maybe its magic not science.

1 Like

I could have used “tied up”, “tightly bound”, or other phrases to make the point. Any way you slice it, wood chips remove nitrogen from being accessible to growing plants. That nitrogen is eventually released but in the short term, nitrogen depletion is a show-stopping bad problem. Remember the gardener I mentioned above? His corn was 6 feet tall 20 feet away from the chip mulch pile but only 2 feet tall near it. He added nitrogen and the plants then turned dark green and grew 4 feet taller in about 2 weeks. I’d bet money the gardener with chips around his brambles didn’t put them down covering the ground 10 feet away from the plants. Bramble roots on average extend 10 feet from the growing crown and I’ve seen some that were 20 feet. If the roots are long enough, the chips can’t cause much problem for the plant.

There are multiple effects from using wood chips. One of the effects is to bind nitrogen while the chips break down. Another effect is to mitigate soil temperature which permits roots - and the plants they feed - to grow with less stress and more efficiency. Pecan trees given a wood chip mulch grow significantly faster than pecan trees on bare soil. BUT - and it is a big one - pecan trees with wood chip mulch and added nitrogen grow much faster than with chip mulch alone. This was documented by Bill Goff and others about 30 years ago. Encouraging rapid plant growth is not just a matter of addressing one facet of growing conditions. Mulch alone won’t fix the problems with brambles. That requires considering soil type, soil nutrition, soil temperature, disease pressure, sunlight exposure, etc.

1 Like

This isnt corn these are blackberries. Fungus and bacterias are thriving it seems. Planted these last month. Woodchips top dressed. One little guy loves his life so much hes fruiting at 4 inches tall.

Not saying this is wrong or right… just how im doin it.

Planted 2022. Primocanes are thickness of a quarter. Its only May. Heavy woodchip mulch when planted and again in fall again this Spring.

If blueberries grow this good im ok.

Those wood chips looks like it’s been outside for a season or more.
I would think some of the smaller pieces may have already disintegrated and started returning the bound nitrogen.

I’m also planing to cover my newly planted raspberry rows with wood chips (mine are 2 years old and look like yours).

I use wood chips on pretty much everything. Besides what’s already been said, as a plus, it also helps prevent erosion, especially on mounds. It also can prevent soil particles from splashing to the underside of leaves, making the area less prone to disease.

I grow blueberries and blackberries (and most everything else) with bark mulch.

I put down new woodchips each spring as needed.

I fertilize my blueberries and blackberries early spring… b4 buds swell… and fertilize my blueberries again after last fruit picked… (normally mid july)… and fertilize my blackberries again after the fcanes are done fruiting… i cut them out and fertilize the pcanes (normally early Aug).

I have rabiteye blueberries… 5 ft tall and quite bushy. I mixed a lot of peat and compost into my planting beds… my soil normally test between 5.5 and 6. Rabbiteyes… seem to be ok with that.

2 Likes

No they are very very fresh. I got the load in April and they were putting off steam on the trailer… full of green leaves. I usually start in March or April when they are clearing power lines and they dump them locally and offer them for free.

I prep my rows 6 months to a year in advance…i will attach a picture of a row that has been waiting a year for a cultivar that has taken me 2 years to obtain. The thing with the ones that i grow for the most part is that there is no room for error… if they fail then i cant get them again.

Row prep is mostly just adding leaves from my property… along with some horse manure and woodchips that i mix. When i am ready to plant its teeming with life and woodchips get eaten quick. I guess another thing is the worms… alot of folks love worm castings ‘black gold’… i have also talked to folks that hate worms… maybe thats what im doing different…i dont know. I do know that my worms eat woodchips and leaves… so maybe i have more worm castings than normal due to the row prep.

I am asking alot of questions about blueberries because again im growing a few that are very hard to find. I have asked every soul that i could find about getting Cara’s Choice… i lucked into finding 8 plants on Friday… so i really only get one shot at it. If i fail then i probably wont be able to get them again.

This row gets fed leaves and woodchips and manure every couple of months and it looks like i havent added a thing to it…they just get eaten.

I will put this in my notes…

My mentor only fertilizes cane fruits during flowering… and not again until the next year same time… which i also do. We use other methods instead of fertilizer in spring and fall so will keep this in mind.

Not meaning to highjack the thread but are your Obsidians flowering? Mine just set flowers… may have a few fruits even though they are just younglings.

@krismoriah … no blooms yet on my obsidian… i only have pcanes at this point… and they are near 2 ft tall… growing nicely.

I would not expext blooms until next year when they are fcanes.

I have some odd stuff happening with Ohio Treasure Black rasberries… they sent up some very nice pcanes last year… which i tip pruned around 4.5 ft… and they then sent out a bunch of fruiting laterals… which did not fruit last fall (they are supposed to double crop)… but did not happen… then over winter (3F) here…most of those fruiting laterals died. And here is the odd thing… this spring they sent up several (what looked like pcanes) but those canes are blooming now. 3 or 4 ft long and tips are breaking out in blossoms (like they should do in the fall).

They look just like new pcanes… but are coming off of buds located at the very bottom of the canes that grew last year.

OTB seems to be a little confused with my southern heat… it may be ok in a more northern location.

I am back home now… we were visiting my wife’s mom earlier.


These are some of my older blueberry bushes… that tifblue front left has a shoot near 7 ft. They are pushing a lot of new growth this year (all that lighter green growth) and have a decent crop of berries on too. Wood chip mulched…

This is what my obsidian look like today… 2 crowns there and i am letting each crown push 2 canes.

4 Likes

@krismoriah @steveb4

For comparison… pcanes on my older logans… Monsters already.

Obsidian may do better in a year or two.

1 Like

@TNHunter
Obsidian in flower. I am behind you in top growth but i think i will catch up. No fertilizers only fresh woodchips in an unprepoed row. I am pushing my spacing limits with this new row… i will add manure next time it rains.

2 Likes

I got the same fiberglass rods from Tractor Supply.

What is your spacing? 5 ft?

@sockworth … that is where i get those fiberglass rods too. They work great for something like a raspberry or anything you need to support.

I could not say for sure on the spacing on those blueberries probably not what is recommended :wink:

3 … 4 ft ?

1 Like

RE: wood chips as mulch.

We’ve used wood chips extensively as mulch for trees and various garden plants for 15 years. Many years we’ve received 60 truck loads or more.

While there is some research which indicates top dressed wood chips can deplete N at the soil/wood chip interface There are generally few plants with a root structure that close to the soil surface. Wood chips should never be incorporated, unless the site is expected to remain fallow of desirable plants for a season.

Fusion, if you can find any links to the pecan research caused N deficiency by top dressing with wood chips, I’d like to read it please. Unless the pecan trees were brand new transplants, I can’t imagine an N deficiency by top dressing wood chips. As you know, pecans have very deep root structures. But every climate is different, and every soil is different, so I can only verify what I have seen in my climate with my soil.

My experience is that plants and young trees are substantially more vigorous with wood chip mulch in my climate, with or without supplemental N. This would be on non-irrigated plants and trees.

I suspect the mulch benefits (some mentioned by Fusion and Kris) outweigh any possible N deficiencies in most cases (i.e. water retention, less soil compaction, more overall nutrients, more mycorrhiza, soil temperature moderation, weed suppression, etc.)

My opinion is that wood chips start to break down so rapidly it would be difficult to produce an N deficiency in my climate. A load of wood chips which has sat on the chipper truck just a couple days is so hot it’s steaming when it’s unloaded, so the breakdown process seems to start immediately. After a heavy rain these wood chip piles will produce a visible “compost tea” at the base of the piles, which I suspect has supplemental N, since the most broken down part of the mulch will leach away first. My theory is with a heavy mulch pack, every time there is a heavy rain, the plants/trees get a small dose of supplemental N from the compost tea.

Dr. Linda Chalker-Scott has several good articles on arborist wood chip mulch. Below is one.

We use hay (occasionally straw) to mulch our tomato plants (we add no supplemental N to the tomato plants). The plants are almost overly vigorous even without supplemental N. We’ve observed the same with wood chips. Tomatoes are noted for shallow root systems, so N deficiencies should be more pronounced if there was a problem using wood chips.

One could argue that since we are applying it every year, the soil has banked enough N that subsequent wood chip or hay layers aren’t able to rob the soil of N. But even the first year applying wood chips or hay does not produce an N deficiency. We continue to add rows of tomatoes, so this has been observed many times.

Here is a pic I took a couple days ago where we are in the process of again adding mulch (this time hay) as a top dress to the tomato rows.

6 Likes

@krismoriah … blooming on primocanes in early spring… that is just odd.

Mine are not doing that.

When I started mine last fall… they came with about a foot of growth. I left that on and it stayed nice and green until hard frost. I left them until this spring… which made them floricanes… and they greened out this spring and looked great… no winter damage at all.

But when my pcanes started coming up… i cut all thise short fcanes off… leaving only the pcanes.

If i had left those short fcanes in place… i am sure they would have produced some blooms.

Are you sure your blossoms are on pcanes ?

I thought i had blossoms on pcanes on OTB…but when i inspected them closely i could tell the growth that was shooting up and blooming on the tips was coming off very low buds on fcane.

I will keep an eye on my obsidian and let you know if they produce any blossoms on pcanes.

If you think about it, when you apply wood chips, you are allowing those plants growing under woodchips to access the stored “energy” (loosely used) which the original tree spent years of its life accumulating into its own body. No wonder it works so well.

3 Likes

Those are floricanes on mine from when i planted them i didnt trim… and there is some primocanes mixed up in there. I didnt trim mine or do anything other than plant it… im losing energy by letting it bloom and letting the floricanes still live…thats why im behind you in top growth… however i should be getting very good root growth with the way things are looking and once they set in…i will catch up to yours. and hit the top wire i hope.

The row that these are in…are mostly ones that i have multlples of… Obsidian, Halls Beauty, Columbia Sunrise, WIld Treasure, Siskiyou, Silvan, Tayberry, Thorny Logan, Cascade, Newberry, Tayberry, Black Diamond etc. All are babies and planted at the same time… i made a huge mistake and was given a bale of straw which i thought would help…it gave some voles a home and i had to reset and replant a few varieties. they gnawed on the root growth.

Since we are on the blueberry topic… im not sure if you shared your planting methods on your blueberries… but if you dont mind can you tell about your holes…and what you put in them to get them going?

As of right now my local u-pick said to shovel 1 foot down and a 2-3 foot wide hole and put that dirt in a wheelbarrow…and mix it half and half with peat and put that in the hole. Which will end me up in a bit of a mound… Top dress that with woodchips. I asked about mixing with pine fines…they said that they dont… but dont see why not.

1 Like