Coconut coir stunted growth, yellow seedlings??

Central Valley, CA(Zone 9a)

I intially started my fall seedlings in coconut coir seed cells. The second batch were started in peat cells about a week later.

There is a huge difference between the seedlings. The ones in the peat cells are very healthy and large, about 3 times the size of the ones in the coir. Moreover, the ones in the coir are very stressed. Their leaves are yellowing and the stacks are purple.

Nothing is different between the seedlings except for the type of cells. Same light, starting medium and even the same types of plants.

Has anyone else had similiar experiences with coir?

Calgary, Canada

Coir is not a good gardening product and it is not environmentally sound to use it.
I bought some by mistake and finally buried it. Nothing will grow where I buried the coir.

Elmira, NY(Zone 6a)

I don't know about coir, but I know that some plants really love the acidity of peat and will germinate well in it and not germinate at all in other stuff.

Dublin, CA(Zone 9a)

One issue could be that they need fertilizer--coir doesn't have any nutrients in it unless you add them. The seedling will sustain itself for a bit with the seedling leaves, but once they have their true leaves if you don't give them some fertilizer (diluted so as not to burn), they would tend to look a bit sickly. The other possibility is that coir can tend to be high in salt--most reputable sources selling it for horticultural purposes ought to supply coir that's been washed/salt removed, but if you've fertilized and they're still not looking great then that's another possibility.

Also worth noting that coir IS considered environmentally friendly. The whole reason you find coir based products out there today is because of attempts to find more sustainable/environmentally friendly substitutes for peat. Not saying coir is perfect--I don't know enough about all the processes involved in making it, but it's certainly more environmentally friendly than peat is.

Calgary, Canada

Coir is not environmentally friendly when shipped over to here by diesel burning, smoke spewing ships.
The peat bogs in some parts of the world may be becoming depleted, but not here in Alberta.
I prefer to support local business.

Watertown, WI(Zone 5a)

My spring seedlings did better in coir than in peat pots. I did find that fertilization was the key to keeping any of them looking decent, though, so I kept up a regular routine. That said, I probably won't use either peat or coir pots again--they seem to keep my seedlings either too dry or too wet. I'll probably reuse all the small nursery pots I collect over the planting season.

Mountlake Terrace, WA(Zone 8a)

Both coir and peat moss have little in the way of fertilizer in it. The seeds themselves have enough nutrition to start growing, but not much more, using a seedling mix with fertilizer is a good strategy Don't blame the coir or the peat. I start seedlings on a seedling mix, and grow mature plants in coir. All grow well.

Central Valley, CA(Zone 9a)

They were planted in seedling cells MADE of coir or peat not in medium made of either. The medium used is an organic potting soil with compost and fertilizers. Fertilization is NOT the problem.

Mountlake Terrace, WA(Zone 8a)

that's bizarre.

Dublin, CA(Zone 9a)

I'd consider the salt theory then--if the coir that your cells were made of was high in salt, that could leach into the potting medium inside the cells and high salt content would definitely not make seedlings happy. The only other thing I can think of is if coir and peat wick water out of the soil differently, maybe the seedlings in the coir cells ended up consistently a little wetter or dryer than the others.

MIddle Blue, Indonesia

The pure coir is useful for germination purpose only, not as growing medium, because they are lack of nutrient. You must either fertilize or remove the seedling once the true leaf appear.

The coir works great on cycad (sp silver) when compared to the common vermiculite, they enhanced the germination time.

Everett, WA(Zone 8a)

I've seen a few sources report that coir from many commerical sources has a lot of salt in it. One site advised at least three flushes, "pressing" excess water out each time.

For me, a little coir fiber mixed into heavy clay soil seems to aerate it better than peat moss. And I have lots of rain three seasons out of four, so any salt that came with the coir long ago washed away downriver to the sea.

I've stopped using it in potting soil because I'm too lazy (or busy) to rinse rinse rinse my soil components. Maybe if I were smart I'd leave a few bales in the runoff through one fall, winter and spring. Hmm, why not?


Bordentown, NJ(Zone 7a)

I decided to sow my seeds in coir this year because I had a problem with gnats last year. They came in via some invested seed starting mix. I know that most peat mixes are not pre-infested but had read that the gnats don't bother as much with coir.

The coir-sown seeds germinated fine but were in trouble as soon as true leaves appeared. The first true leaves were pale and many of the seedlings died. Here are some pics. These are all petunias.

First, a closeup of green cotedylons (I know that's misspelled) but pale true leaves.

Thumbnail by NisiNJ
Bordentown, NJ(Zone 7a)

Then a comparison of petunias planted in peat mix. Different variety, but still petunias. ALL the varieties of petunias I started in the coir had trouble. And ALL the ones sown in peat were fine.

This message was edited Mar 6, 2011 9:11 PM

Thumbnail by NisiNJ
Bordentown, NJ(Zone 7a)

I tried to save some of them by transplanting them into peat mix today. (Promix) We'll see if they survive.

Thumbnail by NisiNJ
Bordentown, NJ(Zone 7a)

And the final picture is of healthy peat-started petunia seedlings transplanted up into Promix.

Note, RickCorey, that the one on the right is yours from the Robin.

So could it be too much salt? The seed starting peat mix had no fertilizer either. It is Fafard. My (grown) daughter Kat, who gardens with me, tried to help the pale seedlings by bottom watering in diluted MG. Would that have added more salt, and compounded the problem? (I just came across this thread today and didn't know about too much salt in coir.)

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Calgary, AB(Zone 3a)

I tried the coir last year and was very disappointed. I will never use it again.

Elmira, NY(Zone 6a)

If the seedling(s) raised in the coir and transferred to the peat don't make it, you probably were saved a lot of trouble, because IME, seedlings that start out weak usually grow into weak, disease- and bug-prone plants.

I have been hearing a lot of stuff about coir stunting seedlings. Some people say coir is full of salt, others that it's heavy metals. Whatever, it seems to be a problem for a lot of people, which is why I am sticking to peat for now.

Everett, WA(Zone 8a)

I delighted to see my "mongrel" petunias going strong! I was only able to find a few pods last fall, and only one of those pods had any mature seeds. (Late start, early rain, low polination rates?)

I'm going to see how those 10-15 seeds do this year (I think they are now F4 hybrids from several commercial varieties back in 2009 - especially "Pearl's Royal Blue" from Burpee (I think). But mostly I;'m planting petunias I got from swaps. This time I'll try to keep varieties separate.

I heard the suggestion that we "flush" coir before using it. Hydrate it as usual, but then let water run out and try to wring it like a sponge, or squish it to expell as much water as possible. Soak again, squish again.

Or live in the Pacific NorthWet and just leavee it out in the rian for a few days! I like the coarse fibrous teture and would like to use more of it.


Stoystown, PA

This year, I used Burpee's Eco Friendly Seed Starting Mix which was made from the coco coir. It also had some composted natural fertilizer added. The seedlings did ok then quit growing and turned yellow. I am very disappointed with the results from this medium. I won't use it again. I wasted time and money on seeds that sprouted, turned yellow and died. I even tried adding a very weak solution of plant food, a pinch or two to a gallon of water. Only made things worse. Very frustrating. Those seeds I planted in peat based medium are normal. Too late now to replant the seeds. Never again.

Everett, WA(Zone 8a)

I tried making seed-starting mix mostly from screened pine bark muclh, to get more air into the mix and have faster drainage. Despite over-watering, it worked very well for every seed type except petunias. They need light to germinate, hence "sow on surface". My mix was so coarse that they fell into the cracks and were nev er seen again.

Next time I would sow very fine seeds onto a layer of vermiculite laying on top of the pine bark shreds.

Also, for big seeds, I would screen the bark shreds coarser ... rather, I would work harder to get rid of as many fines as I can.

Corinth, MS

yeah i started these roma tomato in perlite. then transplanted to either peat, perlite, fresh pine bark fines, or composted pine bark fines. all are fed with chemgro 10-8-22. my experience with bark has been poor. this pic is a week old. there is even greater differences now. the peat and the perlite plants are twice the size of the ones in composted bark. the one in the fresh bark is ok, but not as good as the peat or perlite.
from left to right. peat ,perlite (i covered the top with bark to stop evap), fresh pine, and composted fines.

Thumbnail by rebelhead

I am using coconut coir for more than 2+ years to keep garden in healthy condition which saves water. Coir is a very popular planting medium for environment friendly gardening. It is the best alternative to peat moss with long lasting effects.

Till I don't notice any bad effects of using coco coir in gardening. I think you have to consult it with the local coco coir manufacturer or supplier i.e., They provide you the exact solution for your query.

Sydney, Australia

Cocopeat which we buy should have a quality. It must be 100% composted, brimming with beneficial microbes and fertiliser, hydrated. Also it should be originated from the pure husk of the coconut without any addition of chemicals. High quality Cocopeat has unique aeration and high water-holding qualities. The pure Cocopeat is mixed with worm juice and nutrients and then composted to produce the best growing media. So, if we prefer pure Cocopeat, then yellow seedlings will not happen.

East Kingston, NY

Trying to be environmentally conscious this year I decided to try coir as my medium for seed germination and growing on. Everything germinated well and they are growing on with their second and third set of leaves and there is no yellowing. However, I find that the plants are spindly and unable to stand up without support. I realize that coir has no nutrients in it, so I use a very diluted fertilizer each time I water. I think that before these seedling get any bigger, I am going to attempt to transplant them into a standard growing medium mixed with the coir from the pots. I just do not think coir is enough on it's own to grown on seedlings. I have tried strengthening the stems by using a fan to circulate air in the room (to simulate breeze) but it is not helping. The one good thing I can say about the coir is that there has been absolutely no dampening off. Next year I think I will try using a combination of coir and a regular potting medium. I have too much invested to run the risk of losing my seedling crop.

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(Pam) Warren, CT(Zone 5b)

I gave up on coir last year. I loved the idea of it, but the seedlings didn't. I'm not sure what the problem was, but I ended up composting a lot of it just to get rid of it.

Everett, WA(Zone 8a)

Some sites suggest that some coir is sold a little salty.

IF that is the problem, heavy top-watering and removing the flow-through ought to cure that eventually.

Another option is screened pine bark. I don't hear about many people using it for seed starting, but it seems to work OK for me, with around 10-20% conventional mix like Pro-Mix added.

For starting seeds in small cells, I try to get bark screened to be mostly BB-sized to 2-4 mm. If I can get rid of ALL bark powder and fibers and fines I'm happy, because for seed starting I can use things like 10-20% Pro-Mix to make up the water-retaining component. (For potting mix for buckets, I like more fine bark, and coarser bark up to 5-6 mm, frequent watering, and less peat-based Pro-Mix.)

P.S. Maybe bark is good for me for seeds because I still over-water, and screened bark lets me make my seedling mix VERY fast-draining and airy.

P.P.S. If you start tiny seeds that need to be surface-sown, or need light, you can't have a rough or "open" surface. The seeds fall into cracks and die. I add a thin layer of medium vermiculite on top, just enough to fill the cracks and give a smooth surface.

Pueblo, CO(Zone 5b)

No personal experience with Coir yet -BUT-
Nutz4plts: if the plants looked bad and fertilizer made them worse, that does sound like salt. Salt interferes with a plants ability to take up water, and fertilizer can aggravate this. For this reason, you don't fertilize drought-stressed plants, either.
pH can interfere with a plants ability to take up nutrients, soil that is too acid or too alkaline can also cause yellowing - but fertilizer shouldn't make it worse unless you used too much. Organic matter that is breaking down can tie up Nitrogen and make it unavailable for plants, but you should see some improvement with fertilizer.

Denison, TX(Zone 7a)

I use coir as well, and normally have good luck with it.
I never have damping off problems, and it's very easy to use, to water, and from which to re-pot seedlings. The *only* problem I might see are gnats, and when they become evident, I back off on the watering and add Bt Thuringiensis. Problem solved.

However, this year I am seeing the same problems as originally posted (in 2010) by dlbailey: "The leaves are yellowing and the stacks are purple." Specifically on my tomato and pepper seedlings.

Most of this year's seedling are already out in the garden beds and doing well. The only ones left are the tomato & pepper seedlings, a few amaranth, cabbage, and swiss chard (all from Baker's Creek.)
None of these seemed mature enough to take out with everyone else.

However, I DID pot them up into "garden" soil (the name escapes me, but it's a very peaty, enriched mix) Still, weeks later, nothing seems to be actively growing! There are no additional leaves on any of those mentioned. In fact, several of the amaranth in the same pot have died, leaving only one or two seedlings.

I've fertilized with a weak solution of Alaskan fish fertilizer. Still no change.
I'm beginning to think I need to take them out and place them (still in their trays) on the garden beds for....I don't know....revitalization? :) Even though they get plenty of sun in the greenhouse, they act like weak shut-ins!

(The included photo is btwn potting up all seedlings and taking some out to the garden)


Thumbnail by Rookerie
(Pam) Warren, CT(Zone 5b)

This year I did a lot of experimentation with growing media, and ran into the problem of fertilization. I was used to MG, because that's all that was available locally, but started mail-ordering better brews geared toward micro nutrients and drainage. No more time-release fert. Maxicrop, a seaweed type, didn't seem to have much of an effect except for germination. Then I started using Peter's Classic, half-strength because I do continuous watering, and Wow! What a difference! I've never had such robust seedlings!

Maybe they're just hungry?

Everett, WA(Zone 8a)

Did you test the idea that coir sometimes comes from the vendor "salty"?

You might rig an absorbent mat or towel under your trays to pull excess water out, and then flush them a few times with excess water, probably warm water.

If you have a soft, well-draining soil surface, you could just press the trays down firmly into the soil and then flush them (though that would carry the supposed salt into your outdoor soil).

I stopped trying coir when I read about that. Admittedly, it might have been the "Peat Moss Vendors' Association" that spread the rumor!

Actually, I gave up on coir when I got too much variation from batch to batch: sometimes nice coarse fibers, but usually a mish-mash of powder, fibers and chunks.

East Kingston, NY

Thanks folks for your input about the coir. Started another batch of seedlings (perennials) and went right to using Espoma potting soil. What a difference! Nice, strong seedlings and thriving. Next year, no is enough work nursing my seedlings. I don't want to have to deal with washing coir to remove salt. Just when you think you are doing something good.

Everett, WA(Zone 8a)

I also had very high hopes for coir. Coarser and longer-lasting fibers than peat, high water retention without necessarily reducing aeration, sustainable ...

Too bad the vendors didn't think about quality control.

I suspect that, when an industry finds a way to sell what used to be a waste product for them, that they have a hard time thinking about the "quality" of their waste products.

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