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Question about water retention/drainage

Posted by caterwallin 6-PA (My Page) on
Fri, Feb 3, 12 at 16:11

With the 5-1-1 mix and the gritty mix, are they both water retentive and also have good drainage? When I decide to take the plunge and start using these mixes, I'd like if they wouldn't get water logged if it rains a lot, and it would also be nice if I wouldn't have to be watering them more than once a day in the summer. Is it possible to have both or is it asking for too much? Every year I have some plants in 3-5 gallon containers and have them planted in potting soil; some days it feels like I'm constantly watering them in the summer. Sometimes they get so dry that when I water them the water runs right through and out the bottom of the pot. Would that happen with Al's mixes?

I sure am excited to try them if I can find all of the ingredients. I'm in central PA and there's a Farm & Tractor Supply (right name?) store in the area where I could probably find the grit. I'm not sure about the turface. I could probably get pine bark (mulch) at Lowe's. I almost have to go with whichever mix I can find the ingredients for. At least I guess either one would be better than what I'm using for the plants now.

I have an Amorpha fruticosa that I have in a 5-gallon pot and is about 3 feet tall that I want to use one of these mixes for. I also have 2 hackberry trees that I'd like to do it with too. I also have a crabapple tree that's been in a one-gallon pot for about 3 or 4 years that I'm not sure what I'm going to do with yet. Maybe it's good for bonsai?

Oh, and there's a feed store up the road a few miles from us that I can maybe get the grit from (either there or that tractor/farm place). Am I right in understanding that I should ask for grit that doesn't have calcium in it? I'm wondering, though, why a feed store would carry such a thing when chickens should have calcium in their diet so their eggs have thicker shells (isn't that right?).

Cathy


Follow-Up Postings:

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RE: Question about water retention/drainage

If your worried about water retention, try filling the pot with the drainage holes are plugged, let it sit for a few minute the drain it, this would allow the mix to absorb as much as possible. Inevitably, you will have to water at least once a day if it gets to hot, but it will help with water retention.


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RE: Question about water retention/drainage

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Feb 3, 12 at 21:11

Hi, Cathy. Over the course of a year, I maintain a LOT of plants in both the 5:1:1 mix and the gritty mix, some of them in very small pots (bonsai). The only plants that need watering every day with any regularity are a few mature plantings in small container, and usually in July/August. Everything else is usually able to make it 2-3, sometimes 4 days or longer between waterings, depending on where the plants are sited, weather conditions, species .... The exception might be some of the vigorous & thirsty plants like tomatoes, that when mature might be counted on to require daily watering, depending on the cultivar and size of the soil mass.

Fortunately, growing in soils with better aeration allows you to use larger soil volumes than you could when using heavier soils, which helps to increase the intervals between waterings at the same time it eases the stress & limitations imposed by tight roots.

I don't know why, but some growers insist on calling the intervals between waterings unfavorable when they compare well-aerated and fast draining soils to the heavy soils they might be using. This may be true from a grower's personal view when grower convenience is a very significant, if not primary consideration; but from the plant's perspective, soils that require frequent watering offer the best opportunity for plants to grow to their potential. I honestly think it's more reasonable to consider the interval between waterings when using a heavy water-retentive soil as being too long to ensure optimal root health, which would make soils that require more frequent watering a considerable benefit from the plant's perspective.

I don't think you'll be growing your veggies or mixed display containers in the gritty mix, but even if you did, about the only time I've seen the gritty mix difficult to rewet is when the grower is using organic fertilizers, like fish emulsion and various meals. These fertilizers sometimes promote algal growth on top of the containers that when dry, form a hydrophobic crust. If this crust is absent, even a completely dry gritty mix is easy to rewet. The Turface absorbs water very quickly, and the surface of the granite is easily rewetted. Once that occurs, even if the bark had dried down to below about 30% moisture content (the approx point at which bark and peat become hydrophobic), the water absorbed by the Turface and adsorbed by the granite diffuses into the bark, bringing its moisture content up enough to break its tendency toward hydrophobia. It's best to water a very dry gritty mix twice at 10-15 minute (or longer) intervals, as the second watering allows water to move into the formerly dry bark particles.

It's more important to not allow the 5:1:1 mix to dry down to less than 30% moisture content, lest it become difficult to rewet. The same guideline is true in peat-based soils as well.

What city/town do you live in, or what large city are you near? You don't want a grit that has any Ca or salts added, and you don't want grit made of any fraction of shellfish. Look for crushed granite or quartzite if possible.

Best luck, Cath.

Al


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RE: Question about water retention/drainage

Bob, True, that's a thought to find out. I might try it.

Al, Thanks for that very detailed thorough explanation. I don't know how you got to know so much but after you say it it makes sense to me. I just wish I could think of all of those things! ;-)

I won't be growing any vegetables in pots because I grow all of them out in the gardens. I raise butterflies and release them and what I have in pots are plants that are host plants for butterflies like the Amorpha fruticosa, rue (I also that planted out in the one garden), hackberry tree, birch tree, and milkweed. I plant at least 50 tropical milkweed plants in 3-gallon pots every year for the Monarchs and will probably keep planting them in potting soil because it would cost me too much to replace all of that potting soil with 5-1-1 mix. They've done pretty well so far that way; it just seems like I have to water them a lot though.

I live in central PA, about 50 miles north of Harrisburg, although I wouldn't travel that far for anything. Other than that city, the only city closer to me than Harrisburg (population about 50,000)is Sunbury (pop. of about 10,000), which is much smaller than Harrisburg. Williamsport (pop. about 20,000). I'm not sure what businesses in the Sunbury area would carry Turface, grit, etc. I hope that there is someplace(s) where I can get those things so I can at least put my Amorpha and potted trees in the gritty mix. I'm sure that I could find the ingredients for the 5-1-1 mix in the area if I'd use it for some/all of those things that I mentioned, but I guess the gritty mix would be better for the long haul.
Cathy


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RE: Question about water retention/drainage

Oops, I should have proofread before I clicked the submit button. About Williamsport...I mean to say that it's about the same distance from us as Harrisburg, only to the north instead of the south.


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