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RE: Container Soils and Your Plant's Nutrition (Follow-Up #118)

posted by: tapla on 03.24.2013 at 06:14 pm in Plumeria Forum

Should I rinse the lime out of the screened bark I am assembling for the gritty mix? So far I have only about 4 gallons. First, thanks for the kind comments. If it's not a hardship, I'd use the bark you already limed as an addition to the 5:1:1 mix or somewhere else. If that's a problem, rinsing it thoroughly will help, but since dolomite is only very slightly soluble, there will be a residual fraction, though I doubt it will present a problem if you at least try to flush it out. If you notice any chlorosis as a result of a pH that might be a little north of Ideal, you can just add a little white vinegar to your irrigation water for those plants in the limed bark ..... but as noted, I wouldn't anticipate a problem.

I have been digging some fir bark into my garden beds over the past few years to provide some organic matter and aeration. This before I came upon your excellent and informative threads. I didn't know about adding lime to bark beforehand. Am I in deep trouble in the beds? Can I do anything to ameliorate the situation? I don't think any action is necessary. The buffering capacity of the soil is very significantly greater than the bark and small amount of lime you're adding, so unless your soil (in the beds) is already very basic, there shouldn't be any problem.

I usually keep my potted trees and hydrangeas over the winter in my unheated garage along with my potted tulips and lilies (thwarting the squirrels/mice/critters). One half of the garage (my potting shed) is separated by a wall and has its own door so temps don't fluctuate when garage door opened. I make sure the pots are well watered before I put them in the shed in October and check on them in March/April. The temperature inside can go down to -16C but gradually and warms up slowly in the spring. I can avoid the big swings in spring temps. I usually bring out the maples when I see the in ground ones starting to show signs of bud break. That's a great strategy. I bemoan the warm temps in my garage where my stuff over-winters, every year. I wish I had a large pit, like many of my bonsai friends, where I could keep things quiescent longer - so I don't have to move the early risers in and out of the garage as temps allow - after they put on their spring flush.

My problem is room. I have a dark enclosed storage space under the front porch that would accommodate a 4 foot high pot & tree combo. The floor is concrete and if I put the pots against the house wall and covered the exposed sides with bags of leaves or sawdust what do you think? I think it would be colder than the potting shed but it would be out of the wind and sun. Sounds good. The only concerns are root temps that react killing lows and dessication (soil/roots). You might find that any elaborate insulating efforts are unnecessary - depending on where you live & the plant material.

I had assumed (wrongly?) that the perlite/granite and the Turface/FloorDry were inert and the lime was reacting only with the bark. Technically that's correct, but the dolomite is a source of Ca/Mg, as well as being a pH adjuster, so it's a part of the chemical composition of the soil as a whole.

In the 5:1:1 mix can I skip the sphagnum moss and add the finely ground bark instead? Or just leave the moss out and rely on the fines from the 3/8" screened bark? I look as soils as a compromise. In general, the more often you have to water, the greater the potential for healthy roots - as long as you're willing to keep up with the watering. You could grow perfectly healthy plants in a bucket of broken glass, if you wanted to water 5 times each day. Some growers are simply not willing to admit that the fact they can't or won't water more frequently has an impact on their plants' potential. We admit that not eating right or exercising has an impact on our potential, but somehow it's difficult to admit that plantings that go a week between waterings with no trouble are limiting our plants. They do - period. There is no way you can partially inhibit oxygen to a large fraction of the root mass and not affect growth and vitality. What the grower needs to find is the right balance between how often they are willing to water, and how much potential they are willing to give up. Personally, I look at the size of the plant and repot it into a pot that I will need to water daily or every other day when the planting is mature. You'll learn how much peat you do or don't have to add based on a visual assessment and by feeling the texture of the soil after the first year. After that, you'll be able to make soil like your grandmother baked bread - by feel and based on your experience. When you start with a large fraction of chunky material, it's a lot more difficult to go wrong. Conversely, when you start with a large fraction of fine material as the base of your soil, it's going to have water retention issues. Even though there are ways to ameliorate those issues using tricks like wicks & tilting the containers, they don't change the reduced aeration inherent in soils based on fine particulates.

I'm on the hunt for coarse perlite. Try a hydroponics store or greenhouse operations that make their own soils - but ask early because they might need to order it for you. The stuff available is very fine with a lot of dust. It is lighter than the granite which makes a big container very heavy. Does the angular surface area of the granite provide more surface area than the rounder Perlite? No - the perlite has more surface area on a size for size basis, and holds a considerably more water (on its surface). If you use the perlite as a substitute for granite, you need to use more perlite ands less Turface to get the same amount of water retention. Something like 4 Perlite, 3 bark, and 2 Turface, would be about right.

A hundred thank yous for figuring out the optimum fertilizer numbers for us. You're welcome. This is a chart of the
average usage of each element plants take from the soil.

I gave Nitrogen, because it's the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.
N 100
P 13-19 (16) 1/6
K 45-80 (62) 3/5
S 6-9 (8) 1/12
Mg 5-15 (10) 1/10
Ca 5-15 (10) 1/10
Fe 0.7
Mn 0.4
B(oron) 0.2
Zn 0.06
Cu 0.03
Cl 0.03
Mo(lybdenum) 0.003

To read it, look at P. The chart tells you that plants use 16-19 parts of P for every 100 parts of N, for an average of 16 parts, which is 1/6 the amount of N the plant will use.

Professionals base their supplementation program on these numbers, but tailored to a specific plant. However, the variance in usage from plant to plant varies little, as you can see from the chart, so thinking plant A or plant B somehow uses nutrients in a ratio that varies widely from other plants is well wide of the mark. If growers wish to increase the number of blooms a plant will produce, they usually reduce the amount of N, which curtails vegetative growth and forces the plant to put more energy into reproductive growth - flowers & fruit. They don't start providing massive amounts of P, because they know what problems are associated with that approach.

Plants are very remarkably alike in how they wish to be treated, and the sweet spot isn't hard to find. Snapdragons, sequoias, and sedum, can thrive equally well with exactly the same treatment. Most of the trouble and limitations surface when we're thinking what we're doing is a good idea, when actually we're asking our plants to thrive when we're providing cultural conditions that put them at the limits of what they are programmed to tolerate. Plants should thrive because of what we do for them, not survive in spite of what we do to them. ;-)



clipped on: 03.24.2013 at 08:59 pm    last updated on: 03.24.2013 at 08:59 pm