Fill For Large Planter

Discussion in 'HortForum' started by nlw, Mar 8, 2008.

  1. nlw

    nlw Member

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    I have a large planter/pot (30" tall x 20" wide) for a Tasmanian Tree Fern. What shall I fill it with? Can I put volcanic rock in the bottom for drainage? Any other suggestions that might be better? I am planning to use a potting soil suitable for ferns, but if there is something better, I am interested in hearing about it. Thanks!
     
  2. globalist1789

    globalist1789 Active Member

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    You can fill the bottom with anything you like. Both rocks and chunks of styro-foam are classic choices.
     
  3. Ron B

    Ron B Paragon of Plants 10 Years

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    Kind of a small container to be putting drainage material into. Large, wide planters can benefit from having drainage material to transport water sideways to drain holes, otherwise the potting medium should go all the way to the bottom, without a layer of differently textured material that will cause water draining through the soil column to back up.
     
  4. Debby

    Debby Active Member 10 Years

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    I just read a thing by Graham Rice that said perlite or styrofoam peanuts could be used in the bottom third of a container...
     
  5. Ron B

    Ron B Paragon of Plants 10 Years

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    Hort. literature abounds with descriptions of and recommendations for erroneous practices.
     
  6. Olafhenny

    Olafhenny Active Member 10 Years

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    I am not sure how big you think a planter should be, before you put drainage material at the bottom. I put a few rock pebbles even into the smallest pot, which I then cover up with a sheet of fly screen, before I add the soil mix. That ensures good drainage of excess water and eliminates any chance of root rot, without wasting pot space for a lot of special drainage material.
     
  7. Olafhenny

    Olafhenny Active Member 10 Years

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    If you expect, that you will have to re-pot into something bigger at a later stage, make sure, that the opening is the widest part of your pot. Getting a plant out of a potbellied container is a major undertaking and almost impossible to accomplish without damage to the plant or sacrificing the pot. I have learned that the hard way and am now using my 'bellied' pots only for annuals.
     
  8. Ron B

    Ron B Paragon of Plants 10 Years

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    Pebbles on bottom of small pot don't insure good drainage actually, the water draining through the soil column backing up when it hits the markedly different texture of the drainage material until the soil above becomes saturated (field capacity is reached), at which point the water rushes through and creates the false impression that drainage has been enhanced by use of the pebbles. Same thing happens in large wide planters, but in this case drainage layer is used anyway so water is transported sideways to drain holes, which are usually farther apart than in a small pot. It's like installing drain lines in a garden with a high (perched) water table, the water will be there anyway and you need to be sure it moves off.

    When you put a drainage layer in the bottom of a small pot you are elevating the perched water table in the pot from the bottom of the pot to the level above wherever the drainage material starts, allowing the plant a shallower and smaller area of well-drained soil.
     
  9. Liz

    Liz Well-Known Member 10 Years

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    eliminates any chance of root rot"

    aka "Dicksonia antarctica "
    http://www.apstas.com/sgaptas-ferns.htm

    Don't think there will be much chance of that with one of these. TheY practicaly grow in the creeks here. Just make sure the soil you give it is good leaf mulchy stuff. That you don't cook it in the pot in warm sun. In fact they are understorEy plants and live a cool moist evironment. To water it place the hose nozzel on very low and dribble water into the crown where the new growth comes out. This is the way they gather moisture fom the rain coming out of a 60 foot + tree canopy. Let the water dribble down the trunk and into the mulchy soil. Only use blood and bone (bone meal) as fertilizer about once a year. You may have to repot it eventually to give it some new soil but if it is in a good sized container it should be fine for many years..
    Liz
     
  10. Olafhenny

    Olafhenny Active Member 10 Years

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    Physics do not seem to back up this assertion, neither do decades of my own experience.
     
  11. Ron B

    Ron B Paragon of Plants 10 Years

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    Gravel in the bottom of containers does not improve drainage. In fact, by reducing the depth of the soil mix, the gravel complicates the drainage process. This is due to the perched water table above the gravel instead of at the bottom of the container as before. A key factor to remember in water relations in soils is: water moves from a coarse-textured material to a fine-textured material readily. However, water will not move from a fine-textured material to a coarse-textured material until saturation occurs and the weight of the water above forces the water below into the coarser material

    --Whitcomb, Establishment and Maintenance of Landscape Plants (1987, Lacebark Inc., Stillwater)

    http://www.lacebarkinc.com/establish.htm

    Nearly 100 years ago, soil scientists demonstrated that water does not move easily from layers of finer
    textured materials to layers of more coarse textured. Since then, similar studies have produced the same
    results. Additionally, one study found that more moisture was retained in the soil underlain by gravel
    than that underlain by sand. Therefore, the coarser the underlying material, the more difficult it is for
    water to move across the interface. Imagine what happens in a container lined with pot shards!

    http://www.puyallup.wsu.edu/~Linda ...ural Myths_files/Myths/Container drainage.pdf
     
  12. KarinL

    KarinL Well-Known Member 10 Years

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    So, apropos that and a couple of other threads here recently including my own about my root-rotted rhodo, is the trick to use coarser potting medium/soil, rather than a dense soil that you expect the water to drain from? This would serve the purpose of keeping roots aerated (and able to stay cool when pot is in hot sun) as well as allowing water to move through the medium rather than being stuck in it.

    A couple of people I know mix styro bits into their soil, and report great results. Personally I can't abide having non-biodegradeable or unnatural stuff in the soil because at some point the pot has to be emptied and I don't want the stuff in the yard. But the concept seems solid.
     
  13. Ron B

    Ron B Paragon of Plants 10 Years

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    Many concepts seem solid but are found not to be when checked out. Great results are not established without controls, if all the plants are given the same treatment there is no basis for comparison.

    When I worked on a rhododendron farm they were potting the evergreen azaleas in pure tree bark.
     
  14. Olafhenny

    Olafhenny Active Member 10 Years

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    That may well be so, as a matter of degree, Fact is that, if there is a void at a lower level, water will fill it every time, providing it has access. I water usually in large intervals and then until it starts to escape from the bottom of the pot. That alone id proof, that it can escape, no matter what your studies say.

    My method of covering a few small rocks with fly screen has two advantages:
    -


    --Whitcomb, Establishment and Maintenance of Landscape Plants (1987, Lacebark Inc., Stillwater)

    http://www.lacebarkinc.com/establish.htm

    Nearly 100 years ago, soil scientists demonstrated that water does not move easily from layers of finer
    textured materials to layers of more coarse textured. Since then, similar studies have produced the same
    results. Additionally, one study found that more moisture was retained in the soil underlain by gravel
    than that underlain by sand. Therefore, the coarser the underlying material, the more difficult it is for
    water to move across the interface. Imagine what happens in a container lined with pot shards!
    [/QUOTE]
    That may
     
  15. Olafhenny

    Olafhenny Active Member 10 Years

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    That may well be so, as a matter of degree. Fact is that, if there is a void at a lower level, water will fill it every time, providing it has access. I water my plants usually in large intervals and then until it starts to escape from the bottom of the pot. That alone is proof, that it can escape, no matter what your studies say.

    My method of covering a few small rocks with fly screen has two advantages:
    - It uses less than an inch at the bottom of the pot, therefore leaving plenty room for soil.
    - It leaves plenty voids between the pebbles into which excess water can (and will) drain and then travel to the drain holes.


    I really don't think these studies are relevant to my assertion, that water which seeps to the bottom of the soil body will drop through the fly screen and then run off with little impairment through the gaps between the rocks to the drain holes. Saturation of the soil with water can therefore not occur.
     
  16. growest

    growest Active Member 10 Years

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    Saturation of the soil with water can therefore not occur.[/QUOTE]

    Hi Olaf--actually if water is coming out the bottom of our containers, saturation with water has occured. It's the only way water will flow downward, is after the capacity of the medium has been reached.

    An inch of rocks in the bottom of a container is reducing the usable depth of the medium by an inch...

    An interesting little project would be to water one of your pots (with an inch of rocks in the bottom) and one of ours (with uniform medium right to the bottom) then slide the root balls out once the water has finished dripping out of the drain holes. If our potting mixes are identical, there will be an identical thickness of saturated soil visible at the bottom of both root balls...only yours will be an inch higher, occuring above the rock layer.

    You're going to a lot of work to reduce the useful capacity of your containers. I'm sure your plants are growing fine...but so are ours...with an extra inch of roots at the bottom of every container and a bit less work expended.
     
  17. Olafhenny

    Olafhenny Active Member 10 Years

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    True, but only briefly. As the water drains out through the bottom, which it can with my method very freely, air voids between the irregular shapes of the particles of the growing medium will re-establish very quickly, aided by the fact, that some of the particles are still absorbing moisture after the excess water has drained out

    I did not say "an inch of rocks", I did say that it will take "less than an inch". How much depends partly on the size of the drain holes. The rocks, about a dozen or so for a 12" pot, less in a smaller one and more in a larger one, combined with the fly screen will take considerably less than half an inch at average.

    Tossing a small handful of rocks in the bottom of a container and a piece of fly screen on top of that, hardly qualifies for "a lot of work" in my books. Both, BTW, can be reused, when it comes time to re-pot.
     
  18. johnnyjumpup

    johnnyjumpup Active Member

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    What if you mixed coarse and fine evenly throughout the big pot, i.e. coarse coir chips, bark or styrofoam peanuts? Would it drain well and use less potting soil?

    What would be an ideal potting soil for big pots. Most commercial ones seem to be mostly peat which is really difficult to rewet. I like the idea of the coir substitute.
     
  19. Liz

    Liz Well-Known Member 10 Years

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    If we are still talking "Tasmanian tree fern"
    I just make a mix of garden soil, plenty of compost leaf litter a dry manure and river sand mix well. In the bottom of the pot I too do the flywire and a small layer of gravel (blusetone road chips/ basalt) river stones would do, broken terracotta. I also mulch the top of the pot and have in semi shade. Watering is done with dribble hose into the top of the fern so it oozes down the trunk.

    Liz
     
  20. johnnyjumpup

    johnnyjumpup Active Member

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    Hi Liz,

    Even in my wildest pushing the envelope I never considered a tree fern attractive as they are. We get lots of snow and as low as -23C in winter. It might ride out the winter in the potting shed, coldest it got was -5C this winter. I was thinking Hydrangea Romance. I have two and want to see what one looks like pink and what the other looks like blue. Hence, one is going in the pot.

    I was wondering about the fine soil to coarse material barrier at the bottom of the pot Ron B and Olafhenny were discussing and wondered if mixing the coarse materials uniformly throughout the pot would stretch the potting soil and provide aeration and drainage as well as some moisture retention from the coir. The pot I have in mind is 20 in across and 17 inches deep. I don't think the hydrangea needs the whole pot. I will have to unpot it for the winter anyway as the concrete pot fills with water and snow and ice. I could put some crumpled plastic plant packs and styro peanuts in the bottom and cover with landscape cloth and then put in the potting soil/manure/compost/sand/coir mix.


    I'd like to plant a hydrangea in my big pot.
     
  21. Liz

    Liz Well-Known Member 10 Years

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    Ah I see. Don't think I will be of much use to you over this as I don't get the snow and cold stuff. My Hydrangeas stay in the garden under the apple trees so they get summer shade. Mine grow in an acidic loam and are mainly blue to purple with good autumn colour if the temps drop for a few crisp nights (rare these days)

    Are you able to put the pot in a sheltered spot and do the winter pruning and then maybe wrapp the whole thing in bubble wrapp or a straw jacket or what ever is used to protect plants to over winter. You could also perhaps make cuttings from prunings to start new plants for the next season. [easy cuttings to make] They do go dormant for winter so probably some protection would keep it going. I wonder what would happen if you had a box in a sheltered spot, put the pot in it and filled the whole thing up with saw dust or woodshavings to over winter. Might be an interesting experiment. I think the soil for the pot still needs to be well draining. Acid will give the blue alkaline will give you the pink. Some of the sites I located also said to mulch well.
    Liz
     
  22. johnnyjumpup

    johnnyjumpup Active Member

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    Hi Liz,

    H. Romance is supposed to bloom on new wood so even if dies back to the ground (which it will) it will bloom on the new wood the same year. The big pot is the problem. I have tried several ways to insulate it over the winter in the past, styrofoam, mulch and wrapping in tarps, etc. The problem is not the snow and ice, but the melt water which drowns the plants' roots. Have lost brunnera, hosta, rogersia, all pretty hardy to this last over the years so don't mind removing the plant and enjoying the shape of the pot over the winter instead of having to look at an eyesore for months.

    I think I read that Romance was developed by a Kyoto plantsman/rock guitarist. Don't you just love gardeners? The photo looked intriguing. Sort of a double lacecap.
     
  23. Liz

    Liz Well-Known Member 10 Years

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    Is there anyway this snow water can be kept off. Storing under an eve (sp) in a shed or maybe using a rubbish bin lid or similar as a collar for the pot.
    I would be encreasing the gravel under the soil and maybe bigger drainage outlets covered by the flywire and the whole pot standing on some blocks of some sort so not in touch with ground. But given I have seen snow a couple of times in my life I guess your problems are dead opposite to my drought conditions. :)

    Liz
     
  24. lorax

    lorax Rising Contributor 10 Years

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    I actually used to build little sandwich-board shelters for the stuff I didn't want to drown. It's pretty easy - just take two pieces of plywood and hinge them together on the short sides. This then just tents over the pot and keeps any snow off, and voila! meltwater is no longer a problem.
     

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