Cocunut Coir--seed starting

March 25, 2010

What are the board's thoughts on using Coconut Coir for seed starting? I'm curious with regards to both seed starting and initial potting up after true leaves appear. Last year i used peat pods to start seeds and then potted up in a miracle grow potting mix. Does the coconut coir have sufficient nutrients to last between potting up and garden transplant? If not, what kind of fertilizer should I use--I have various tomato ferts but have never used them at potting up and I know that dilution is very important here.

I'm not married to coconut coir if people have had bad experiences, but I'd like to identify a non-peat alternative.

Comments (31)

  • markmein

    I use re-uable plastic pots, of a couple sizes, for most of my seedlings, including tomatoes. I've used coir pots with success for seedlings that are sensitive to tap root damage at transplanting, as with squashes. The coir doesn't break down very quickly, so I slice cuts across the bottom and along the sies before planting to help with eventual root penetration. I doubt coir has any nutrients at all that are available to a seedling.

    Also, I don't fertilize most of my seedlings. Only the ones I start too early to get into the ground before they get too big. Not saying that's the right thing, just that I think most seedlings of nominal size don't need fertilizer.

  • tomatomanic

    Thanks, to clarify, I'm not talking about Coir pots (although I have those too) but rather coir-based "coco-peat" that I got in a brick at the garden supply store. I have seen coir-based pellets as an alternative to jiffy pellets as well, but they were only available online and with the retailers minimum order requirement and shipping costs, I declined to spend $30 on them.

  • digdirt2

    I tried 1 brick of it last year after a customer passed it on to me. Good germination - faster than peat based mixes - and doesn't compact nearly as much or retain water for as long IME with it.

    But we found that you have to transplant out of it quickly for seedling survival. Not a problem if you normally transplant at the cotyledon stage as we do but I sure wouldn't use it for growing on for any length of time.

    And as already mentioned, the cost. For starting just a few plants, fine but for large numbers of plants it's just not worth it to me.


  • HoosierCheroKee

    I've used coir (coconut fiber) for three years in a row now. I also use other products for seed starting like peat based mixes with perlite. Just depends on who's got what on sale.

    The coir is economical and easy to use. Coir also is sustainable (renewable annually) product where spagnum moss is mined from limited, ancient resources.

    Some coir sold in bricks is much coarser and has longer fibers than other coir that is finely ground, like in the pellets. But what I've found best is mixing the coir with 25% coarse sand or 50/50 with a cheap bag mix like Plantation seed starting mix made from peat and perlite.

    The nutrient value of any seed starting mix, whether made with peat or coir, is negligible. Neither is going to give you any nutrients to speak of. I depend on the plants to tell me when they need a nutrient boost, like when the cotyledons or first true leaves begin to yellow.

    If the yellowing is even and progressive from the leaf tips inward, I feed the seedlings Miracle Gro or Peters at 1/2 strength and say 1/3 gallon per cell tray bottom watered. If the yellowing is lacey patterned (intervenal chlorosis), I add a tablespoon of Epsom salts per gallon of blue water. If the intervenal chlorosis is advanced, I add 1 tsp. Ironite per gallon of blue water with the Tbs. Epsom salts.

    Usually it takes only one feeding per plug tray between 4 to 6 weeks of age to carry the seedlings to the garden unless they are held longer than 8 weeks.

    In cases where the seedlings show signs of nutrient deficiency while they are outside harding up or holding in 4-inch pots, I might give them one more feeding (overhead and foliar) from a sprinkling can mixing 1 Tbs. Miracle Gro or Peters, 2 Tbs. Epsom salts, 1 Tbs. Ironite in 2 gallons of water (I use 2-gallon sprinkling cans).

    As far as using coir for container grown tomatoes, I have a friend who grows tomatoes commercially in hoop houses and plants 2 indeterminate vines per 5-gallon grow bag filled with 100% coir fiber he buys in blocks shipped from India. He has 5 hoop houses with probably a total of 2,500 tomato plants and has excellent results using coir exclusively. He grows Geronimo, Trust, Big Beef and Fabulous this way (just saying he grows greenhouse cultivars and field cultivars under plastic hoops and in coir medium). He fertigates 4 nutrient injections per 24 hour cycle with a high percentage phosphorus solution, plus a calcium injection once per day. His tomatoes are beautiful.

  • tomatomanic

    Thanks, this is very helpful. I'm trying to stay away from peat for the enviro reasons you mentioned, but it sounds like I'm gonna need a potting mix for stage 2 that has peat in it anyway right? (unless I do what your commercial grower friend does which seems like a whole lot of work).

    I guess what I'm asking is what is a good non peat alternative for both germination and potting up to get me through transplanting?

  • HoosierCheroKee

    Well, I'm currently having an argument/discussion with another grower over at our chat room regarding coir. Seems a study in Florida found coir retained too much moisture and caused seedlings to grow too fast (become leggy) but retarded maturity (with regard to root ball, etc.) and may cause problems for commercial growers who plant mechanically.

    So, I'd rather not comment too much right now regarding coir vs. peat except to say, I have not experienced any problems in the past 3 years of starting plants in coir.

  • elskunkito

    I used coconut coir the last two years for my potting soil mix
    before final transplant. I had no issues with leggy plants.
    I user the more fibrous kind. Some brands are fine as dust, other fibery, and yet other with big ol' chunk of coconut in it.

    IIRC it has no nutrient value. I used it as a direct replacement for peat with vermiculite and compost for the potting soil mix.

    worked great. Prices vary wildly and is much cheaper in bulk.

    Used alone for seed starting for potting up I do not know if it would be wise. It can be somewhat acidic. Check the pH.

  • digdirt2

    I guess what I'm asking is what is a good non peat alternative for both germination and potting up to get me through transplanting?

    That's a good question and off hand I can't think of any commercial growing mix or seed starting mix (other than the coir) that doesn't contain peat in large amounts. Even most of the make-you-own recipes I know of include peat.

    There is always the cheap problematic potting soils but I 'think' even the Hyponex dirt stuff contains some peat. I suppose there is always compost. I know some say they do their seed starting in homemade compost but I don't think it is generally recommended.

    If you want to avoid peat all together then hoosiercherokee 's approach detailed above sounds like the best route to me.


    PS - or there is always hydroponics ;)

  • HoosierCheroKee

    Another thing we discussed this evening was mixing coir with charcoal. I think this might be a good way to go and may even try coir, sharp sand and charcoal ... just give it a trial and see.

  • mickyfinn6777

    From several studies on coir fibre across Europe-mainly for horticulture use as well as private use, it was found that the addition of 20% coir fibre to your normal peat based mix, and well mixed in to an even texture, gave much better results generally,in as far as much better air retention of the compost which is better for the roots being formed, also it was noted that there was far less surface disease problems like damping off disease, grey mould etc,forming on the surface and rotting the little seedlings.
    Drainage problems of the compost was also much improved so that there were no very damp soggy patches retained in the compost.

    Most of the coir fibre blocks or bricks sold usually have a basic starter fertilizer in them already-but I am not sure about the large bales of it.

    Generally speaking the survival rate of freshly emerged seedlings in a coir fibre 20% mix added to your usual peat based mix, is much higher, and healthier seedlings result despite many common mistakes like over watering,not enough air flowing around them etc,etc.

  • mickyfinn6777

    Here is a web site that will explain it all, plus a lot of other interesting things too.

  • mickyfinn6777

    Despite what the web site indicated above says,( as they only use Coir with no added peat)most companies that make good use of Coir fibre still add it to a peat mix, and also often add a further percentage of pine bark fines , as well, which seems to make a near perfect mix that's hard to fualt.
    For those pioneers like the webs site listed above, who have successfully licked any problems using just pure Coir based products-it is a credit due to them, and will no doubt be very useful in the near future as peat bogs gradually run out-but in the meantime much knowledge can be gained from the use of it in various forms and mixes.

  • HoosierCheroKee

    MickyFinn: What has your personal experience been with coir as a seed starting medium? Did you use it straight up 100% or mix it with other materials?

  • mickyfinn6777

    No- I always just used it mixed in with a normal peat based starter mix, it often saved me from a lot of compost surface problems in cold or cooler weather in the early part of the year,such as damping off or stem rot diseases.etc,

    The reason I never used it as a straight seed starter mix, is because when it first became popular three or four years ago, several big horticultural companies had problems with watering issues with it used as a straight compost, as it did such a good job of drainage that it often left the surface of the compost bone dry within an hour of watering, so it was not good for any emerging seeds or seedlings.they often had to keep up the watering on a daily basis for a while -however, since that time they have experimented a lot and have come up with just the right combo's and mixes, where it can now be used as a straight mix.

    One has only to look on the web site link above to the coir pots and plugs photos to see the sort of very good root growth coming through the sides of the pots and plugs.

    personally I still prefer to err on the safe side and mix it with a peat based starter mix, I usually obtain a Coir Brick or block, place it in a large bucket or tub, and soak it for a couple of hours with quite a lot of water-about three gallons, and then when it breaks up into a fluffy easy to use compost as such, I then mix it in with a good brand of seed starter mix 20% minimum-saves me no end of problems later, and the young seedlings seem to lift out of the compost easier when transplanting.

  • tomatomanic

    I had very little success with the coir as a seed starting medium--I don't know if I kept it too wet or what but I got pretty good germination followed by basically no growth and then what I believe was damping off. any ideas?

    Also, I used the coir as the potting up medium for some of the seeds that I originally germinated in peat pods. The ones in the coir are substantially smaller and yellowing--even after some dilute fertilizer with 2-3-1 fish/seaweed solution. What do I need to do to address the yellowing?

  • gardningscomplicated

    I'm using a mix of 2 parts coir, 1 part perlite, 1 part compost, and small amounts of greensand, azomite, rock phosphate, and cottonseed meal. So far, I don't think I'm having any problems related to coir. But I am a little concerned about the size of the perlite. I may try sand next time. I'm using 1.5 inch soil blocks. And I potted up my first one yesterday to a 3 inch block. Last year I used a coir based mix I bought online, and didn't seem to have any problems with it. But I've never used a peat based mix, so I don't know how it compares.

  • struwwelpeter

    Starting this year, I am substituting parboiled rice hulls (PBH) for perlite. I am using a mixture of 2/3 peat moss plus 1/3 PBH by volume. PBH is cheaper than either peat moss or perlite (and maybe coir). So far, so good, but the jury is still out.

  • woodcutter2008

    A couple of weeks ago I posted about my success using Burpee Super Growing Pellets and the quick germination that resulted.
    I ran a little experiment and was getting ready to post my results when I found this older, longer thread.

    I have 3 varieties of seeds: Manalucie OP, Olena Ukraine OP, and Wisconsin 55 OP. All were "fresh for 2010" seeds. I planted six seeds of each variety in two different media. Each media has three separate planting cells for each tomato variety. Nine "cells" with two seeds in each cell. The media is really the item of interest, not the variety. Planting depth, and other factors were as equivalent as possible.

    At three and one-half days after planting (this AM), the results are:
    1) Burpee's Super Growing Pellets (Coir?): 8/18 (44%) visible seedlings.
    2) Regular peat-based seed starting mix: 0 visible seedlings.

    At four full days after planting (this PM), the results are:
    1) Burpee's Super Growing Pellets (Coir?): 16/18 (89%) visible seedlings.
    2) Regular peat-based seed starting mix: 0 visible seedlings.

    Of course, germination and emergence is only the start, but my previous batch of seedlings grew well to transplant size and were planted in regular potting mix.

    I'm very impressed!


    Here is a link that might be useful: Another

  • gardningscomplicated

    struwwelpeter - I'd be interested in hearing how the rice hulls work out. I'll probably use up my perlite, then look at alternatives. I'm not so sure my perlite's a problem, but I'd rather have something that doesn't create so much dust.

  • woodcutter2008

    Last update on the germination experiment:

    5-1/2 days:
    1) Burpee's Super Growing Pellets (Coir?): 18/18 (100%) visible seedlings.
    2) Regular peat-based seed starting mix: 5/18 (28%) visible seedlings.

  • struwwelpeter

    struwwelpeter - I'd be interested in hearing how the rice hulls work out. I'll probably use up my perlite, then look at alternatives. I'm not so sure my perlite's a problem, but I'd rather have something that doesn't create so much dust.

    See some of my potted tomatoes here. I also tilled PBH into my top soil and planted some tomato plants there yesterday and today. One problem is that the hulls are packed into the bag so tight that they are difficult to remove without first cutting the bag open along its length. Riceland PBH comes in very nice fiber reinforced plastic bags and it's a shame that I can't easily reuse the bags.

  • gardningscomplicated

    struwwelpeter - Sorry for the late response, but those plants look really nice. Mine did alright with the perlite, but I may try the rice hulls next year, if I can find any around here.

  • nygardener

    I've had very good success with peat-based seed starting mix. Sometimes I use organic potting soil, which has slow-release nutrients that help the seedling once it's started to leaf out; my favorite is Ocean Forest.

    As for coir, there's some debate about which is more environmentally friendly. The pro-peat camp say that North American peat bogs regenerate more peat than is taken out for horticulture each year, and that coconut coir robs tropical regions of organic matter for soil regeneration, and requires a lot of fuel for transport.

  • plantslayer

    There a fellow named Al (user name tapla) who has posted many times on potting soil- I believe he is a pro greenhouse/nursery grower. He has a recipe for _potting_ soil that uses many parts of pine bark fines, and a small amount of peat. I wonder if it could be tweaked to make a starter solution? Maybe you could grind the fines up a bit more? Also, you could probably use coir to replace the peat in the recipe.

    See one of his many threads here:

    He is somewhat of a divisive person from what I gather, but what he says about potting soil seems like pretty useful information.

  • gardningscomplicated

    I stay away from peat, because I don't believe they can restore a peat bog (or whatever it's called) to the way it used to be. Just like I don't think they can clean up the gulf and "make it whole" after bp's oil gusher. But that's just my opinion, and I'm no expert on peat. I'm also no expert on the environmental problems with coir. I'd be happy to find an alternative to both, if there is one. Anyone know what they used before peat? I think I read somewhere that they used to use blocks of sod. Maybe it was in one of Eliot Coleman's books.

  • oregonwoodsmoke

    I gave the COIR a test drive. Mixed 50/50 with sand, it worked fine, but no advantages that I can see and it is very expensive.

    They tell you that a block of coir soaked in 3 gallons of water gives you 3 gallons of coir---- no it doesn't, it gives you 3 gallons of water soaked into a little sponge. The stuff is darned expensive.

    You can use pine (or fir) bark fines. That's a major component in potting soils. If you buy by the cubic yard, bark fines are very inexpensive compared to potting soil.

    I mix the fines 50/50 with course sand. It drains well and yet holds a nice level of dampness. The top dries pretty fast, but I mist my seeds a couple of times a day and don't water the pot until the plant is well up.

    If the seed pots are wrapped in plastic, they shouldn't need any water added at all.

    I just finally found a source for turface and am about to start testing it. If it works for the potted plants, I'll try some seeds in it next spring. Mostly, though, I bought it or the potted citrus and figs.

    I do not use peat moss any more than I have to. My opinion is that it retains water too well, and wet roots give problems.

  • Robertj0794_gmail_com

    I've been looking at many comments and posts. The medium you use is very important. A good seed starting mix is just one part of the equation. What ever you use for the soil, I've got a great mix of starting solution.
    In one gallon of water add:
    1 table spoon of miracle grow 15-30-15
    1 teaspoon Epsom salt (magnesium sulphate)
    1/2 cup of hydrogen peroxide 3%
    It may sound strange but it works great for all seeds. Also for transplanting as well. The hydrogen peroxide acts as a soil oxygenate and kills fungus/molds also the fizzing helps loosen the soil. For tomatoes and roses the Epsom salts works very well to add sulpher and magnesium to the soil. If your a sceptic try it, it will cost pennies and you most likely have the products already in your house. As a side note you must use the liquid mix quickly. Peroxide breaks down rapidly in sun light or open air.

  • taz6122

    Fertilizer inhibits germination of many seeds. I don't use anything but water and rain water gets better germination than tap. IMO there's no need for fertilizer until they are at least 4 weeks old.

  • Edymnion

    I use coco-coir pellets for starting my peppers (peat is too acidic, along with the non-renewability factors), and I've run some tests on them (as well as on old leftover peat pellets), and my results show "Great for germination, but get them out ASAP!".

    My last batch was 3 broccoli seeds. Two I planted in straight soil, one I planted in a coir starter. After the coir sprouted, I cut the fabric liner off and dropped the whole pellet into the same soil mix I used for the other two.

    They kept pace with each other until just after the first true leaves. The two that I grew in straight soil shot up and thrived, the one that was in the coir stunted and eventually died. No yellowing, just came out one day and it was laying over dead. Pulled it up to examine the roots, they never did grow out enough to reach the real dirt.

    Right now I have peppers I've got started in coir, had the first one come up today. I carefully broke most of the coir away leaving just enough around the nice fuzzy white roots as to not damage them and put it into a starter pot with real soil.

    So, long story short, coir is an excellent way to start seeds. Keeps them nice and moist without being soppy wet (even if you leave the base of them in standing water), but there's no nutrients in there at all, not even enough to let the plant grow deeper roots. Break your plants free and give them the real thing.

  • Peter (6b SE NY)

    My results with it this year are the same, the seedlings are languishing and stunted in it. With my hot peppers, though I got much better and faster germination in the coir (it is a Burpee seed starting mix), the ones in the peat are doing very well and are right on track, but the ones in the coir got severely purple and 2 months now still don't have true leaves. I dug one out and even the roots are not good at all. I think they are a lost cause at this point. Even the brassicas I started in it were slow growing until potting up into a peat mix, the ones I started directly in the potting mix are 2 weeks ahead or so of the coir starts.

    I am transplanting everything else from my later sweet pepper and eggplant sowing out into a quality peat mix in the cotyledon stage hopefully before they wind up stunted like my hot peppers. I did a few last night and removed as much of the coir as I could without killing the seedlings. Some are already showing significant purpling. I will definitely not start my tomatoes in it, which I will be finally planting this weekend! I got this Espoma mix I am trying which looks like real quality stuff.

  • ddny64

    I mixed black gold seed starter with coir and added a very small amount of bio tone to the mix and they are doing fine . I like coir because there is less a chance of fungus or bacteria . I also find it great for cuttings and economical as well.

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