issues with coir

Lately we have been having some torrential rains; for example, 3 1/2' in less than an hour. This has happened several times recently and all of a sudden I have noticed that the soil in containers with coir mixed in and the flats of seedlings I had growing in coir are badly compacted. On the container mix I was using four parts good potting mix to one part coir. Under normal conditions this worked very well for my climate and I had excellent water retention and drainage.
It appears that the weight of the water coming down that fast just packed that coir down solid. I watered one pot yesterday, that had been planted about a month ago, then noticed the water just sitting on top; it did not penetrate the soil at all. I had no problems with older containers where coir had not been incorporated.

I'll continue to use coir as these weird rains are usually rare but I'll I think I will use less or add some Perma til. Today I will have to go out and unpot a lot of things and loosen the soil.

The hydrophobic (water repellent) tendency of your soil is not the direct result of using coir, which, unlike peat, is excellent at absorbing water, even when it's completely dry. It's coming from the fact that the peat incorporated into the soil is drying down to under 30% and becoming water repellent as a result; or, if you're using fertilizers that gain their nutrients from an organic source, it could be from an algal crust that tends to form on the surface during extended periods of wet conditions. I can go into a little more detail on the water repellency issue if you'd like.

You should expect soils with a high % of peat and/or coir to compact. It's what they do. Perlite helps to alleviate some of the compacting, so it would have been helpful if you'd added a perlite component when you added the coir. Even more helpful would have been to incorporate a substantial % pine bark fines in your soil at the same time.

Al

My soil mix has bark fines and there was plenty of perlite and the pots without the coir did fine. I had not had this issue before with coir; it always appeared to wet and drain so easily. It may well have been an algal crust but I found it interesting that it did not occur on an other pots.

dunno

- i read coir should be mixed with at least 20% Perlite.
maybe that is why.

there is a VeryActive Coir Group of gardeners here (DG) under
Self-contained Box Gardens Forum.
- just scroll down the forum list PAST this forum"ContainerGardening"

BocaBob and several others can address coir issues.
- and they are good!

GoodLuck!

Thanks, I'll check it out. We had another 2" of rain last evening and it has not been coming down gently, the bottom just drops out and in less than an hour we can have several inches. The weight of this water is just beating the potting mixes to death to death this year. I am always careful to moisten my potting mixes well before using them. I have found this helps to keep the perlite well incorporated throughout the soil but this year when the pots are so super saturated, the perlite still floats up up and away.

Obviously this weather pattern is strange and I will just have to wait it out but I am still going to start experimenting with Perma Til which is much heavier and won't float.

A soil of 5 parts pine bark fines, 1 part perlite, and 1 part coir or peat will remain well aerated (won't compact) and serviceable even during downpours like you're experiencing.

During periods of heavy rain, it is a good idea to tilt your containers at as steep an angle as possible w/o them being in danger of being toppled in the wind. This changes the volume of soil that will be occupied by the perched water table and thus reduces the total volume of water the container will hold. To prove how well this works, saturate the soil in a container and wait for it to stop draining. Then tilt the container and note the considerable volume of water that exits the drain hole. It works even better if your drain holes are on the bottom at the perimeter, and the/a drain hole is at the34 lowest possible point. After it stops raining & the containers are done draining, simply right the containers again.

Also, inserting a wick into the drain hole and allowing it to dangle below the container 'fools' the water in the perched water table into 'thinking' the container is deeper than it really is. The water molecules will travel down the wick, 'looking' for the bottom of the container and be pushed off the end of the wick by additional water molecules coming down the wick behind them. A wick combined with with tilting the container should go a long way toward solving water retention issues, even in soils as water-retentive as yours.

Permatill is rather large for use in container soils. A smaller product like Turface or NAPA floor-dry would actually be superior at increasing drainage and aeration. I won't go into details here, but if you ask yourself how much Permatill you would need to add to pudding, you'll get a picture of what I mean. When you have a soil of fine particulates and you add a quantity of considerably large particulates to it, it doesn't tend to change the drainage characteristics until it becomes a considerable % (around 60 - 75%) of the soil.

Al

Just curious, the physical principles of perched water table makes sense but wouldn't the soil in the lower part of the pot feel somewhat moist if the soil ball was removed from the pot?

I am using Perma-TiI because that is all I can get and I had to drive 3 hours one way for that. Not all amendments are available all over the country. Chicken grit as you know it, is non existent along the SE coast. They use ground oyster shell for chickens here and that product is way too alkaline for container garden use.

It would be more moist than soil in any other part of the container. The wick won't necessarily remove ALL the perched water, and it won't remove water tightly held in internal pores of the soil ingredients.

I wasn't criticizing your choice of Permatill, only pointing out there are better products. I understand you have to use what's available to get the job done. ;o) I take it you've made a considerable effort to find grit there? I know they use ground shell extensively for grit in coastal areas, but FWIW, I've been able to find it for several people who thought it was not available by contacting potential suppliers in their area by phone from MI.

Take care.

Al

I have asked about having grit ordered but the shipping charges are prohibitive. In the past I have brought it home from travels in other parts of the country. There is just no market for it in small towns with few garden geeks who would buy it.

Except for the coir issues I really don't have any drainage problems. In this heat it is much harder to keep things adequately hydrated than drained. The perma till will be used in large (24") permanent containers to replace some of the bark that breaks down too quickly around here.

OK. Sounds like you have everything under control. I DID do a quick Yellow Pages search for grain elevators (most likely to have the granite - it's chicken grit, so rural businesses that sell feed are likely prospects) and I found 19 possibilities within an hour's drive of you. That's how I found it for the others, BTW.

I'll leave you with the info that conifer bark breaks down at about 1/4 the rate of coir (or peat), which means it remains structurally stable in soils far longer than either. Good luck.

Al

Thanks Tapla, I can get chicken grit all over the place, this is a rural area - but they do not use granite for chickens around here; that is the problem. They use the ground up oyster shell material; it makes for some very strong egg shells however so there is some good from it.

If coir breaks down that fast it is no wonder I am in trouble. Bark practically disintegrates within months in this heat and humidity.

Tip: If you are using organic-based fertilizers, it greatly exacerbates the issue (soil collapse).

Al

I am assuming that would be from increased microbial action??? If so, I see that as a positive thing.

Obviously, increased populations of micro-organisms have to consume something to remain viable, so they dine on the organic particles in your soil, causing it to collapse structurally - something, by what you describe, your soil can ill afford. While we all covet organic matter and the benefits the large populations of micro-organisms that come along with it bring to mineral/garden soils, trying to promote large populations in container media can be problematic. There are very distinct differences between what works well in gardens and what works well in container culture and these practices are very often at odds with each other.

Al

WOW the scientific talk on this topic is facinating and very informative,
thanks guys!
Ann

My containers are year round plantings and a richer soil helps keep the plants healthy and happy through all their seasonal transitions.
IMO, more microbes means more mycorrhizae which helps deliver more food to the roots.


LOL Annabell, it does sound geeky.

Ok - but your original post says your 'richer soils' are NOT keeping your plants happy because of the rain - and possibly other reasons, if you read between the lines; yet, when the science is discussed that illustrates specific areas that could be worked on to bring about the changes needed to relieve the soggy soil situation, it's geeky.

Your plants don't need a "richer" soil to be happy and healthy, nor do they need symbiotic relationships with mycorrhizal fungi to be happy. They also don't need more microbes to deliver nutrients to the roots as they break down your soil's structure. In fact, because of the compaction and water retention you describe, your soil is a very poor environment for any type of soil biota, except perhaps anaerobic forms. With a suitable nutrient supplementation program, your plants would grow just fine (read that to say 'better') in a totally inorganic, appropriately sized mix of nothing but Turface & pumice, expanded shale, or crushed granite (even though I'm not suggesting you adopt a mix like that). I can say this because I've grown in mixes like you're using now before I took the time to study soil science in considerable detail. I grow many perfectly healthy plants in soils with NO organic component in them and I can guarantee you wouldn't have to suffer the issues you lament in your opening post if you were open to suggestions.

Al