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ellenr22

great idea for a pebble tray

I was in the supermarket and I saw a roasting pan and rack which would make a great pebble tray.

The drawback is I don't think it would look too good on my plant table.
but it would be easier than balancing my pots on small pebbles.

Comments (20)

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Good idea, Ellen. Pebbles and water in the pan and plants on the rack - tidy and effective.

    Al

  • ellenr22 - NJ - Zone 6b/7a
    Original Author
    9 years ago

    Al, do you know if the pebbles in the 'usual' pebble tray serve any function other than to keep the pot raised above the water level?
    I decided to go with my idea of a rack and I can buy a foil pan in the dollar store, but I also have pebbles I bought.

    any purpose served by putting them in the water, since I don't need them to raise the pots?
    maybe they contribute to more humidity...

    thanks,

    ell

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Yes, the pebbles increase the surface area from which water can evaporate. For instance, a 10 x 13 cake pan filled w/water would have an evaporative surface area of 130 sq in, but if you arranged a single layer of Hydroton clay spheres in the bottom of the pan and added enough water to cover them by half, you would more than double the evaporative surface area, so water would evaporate from that arrangement more than twice as fast. Also, the material you use impacts evaporation rates. If all the spheres were the same size, water would evaporate faster from the surface of rocks (because of their surface porosity than marbles, and faster from hydroton than rocks.

    Keep in mind though, that once the rocks or whatever you use are covered by water so the water's surface is unbroken, the marbles/ rocks/ Hydroton/ other, serve no purpose insofar as evaporation is concerned. Even a sponge half covered by water in the pan adds a lot of surface area, so by extension, increases the rate of evaporation.

    Al

  • ellenr22 - NJ - Zone 6b/7a
    Original Author
    9 years ago

    hmm...I need another cuppa coffee. :) So - to get the most evaporation surface - is the distinction to use the pebbles, and cover the pebbles only half-way, rather than totally?

    thanks, I really appreciate your knowledge, altho sometimes I am rather slow .lol.

  • asleep_in_the_garden
    9 years ago

    Pebble trays just took on a whole new significance for me.

    Surface area..of COURSE! *slaps forehead*

    Thanks Al!

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Yes - the shape of the surface can have a very large impact on the actual surface area. For example: Turface is a baked clay granule so porous that 1 lb of the product can have up to 14 acres of surface area. Seems impossible, but that's a figure the manufacturer uses to illustrate the product's porosity.

    Al

  • asleep_in_the_garden
    9 years ago

    Real quick off topic question for ya Al...regarding turface,are there any brands that one needs to avoid because of added stuff that's toxic,or is any turface product okay?

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Turface is nothing more than (Montmorillonite) clay, fired (calcined) at temperatures high enough to fuse the clay particles together so they form a ceramic-like particle full of pores that occur as the water in the clay turns explosively to steam, so there would be nothing phytotoxic about any of the Turface products unless Profile Corp had agreed to produce the same product under a different name and add dye or perfumes to it - say, if Profile contracted with Kittypoo Corp to produce green colored cat litter that smelled like daisies. None of the products produced for apps like sports fields or golf courses would be phytotoxic. They're designed to HELP plants grow, so one of the fundamental requirements would be that the product should be safe for plant material.

    Schultz (the fertilizer company) contracts with profile to bag Turface MVP as their own brand of soil for aquatic plants (Schultz Aquatic Soil for Plants). All it is, is Turface MVP at twice the price of MVP. Espoma does something similar by packaging Haydite as 'Espoma Soil Perfector'.

    Al

  • asleep_in_the_garden
    9 years ago

    After some digging around I think I figured out where I was going wrong...my question wasn't actually about turface but about the stuff you can pick up at an auto parts store to sop up oil spill with. Any of those that are a bad move?

    Again,apologies for derailing the thread...I'll behave myself after this last intrusion. ;)

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Yes. Calcined DE is often treated with clumping agents and/or perfume when used as cat litter. Also, it's often fired at temps too low to ensure stability. A good stability test: Freeze it in a cup of water overnight. If the particles are still stable after it thaws, it's stable enough for use in plant media ...... if it's free of clumping agents and scents.

    Al

  • asleep_in_the_garden
    9 years ago

    Excellent!

    Thanks for the info!
    The freezer tip in particular will help a lot!

    Appreciate your help in this small matter :)

  • ellenr22 - NJ - Zone 6b/7a
    Original Author
    9 years ago

    so if I understand Al's comment re surface area, if I raise the wire rack and put shards of pottery below the rack, cover them halfway with water, I will have more humidity?

    btw the rack works great, so much better than balancing pots on pebbles. Plus it lets me group my high-humidity plants together, and takes up less room.

  • paul_
    9 years ago

    An issue with this idea to consider -- keep in mind that even stainless steel will rust after a time if constantly exposed to water. I can say from personal experience that the aluminum/foil roasting pans can develop holes in them over time via chemical reactions.

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Ellen - yes - that's right; and pottery shards are a very good choice because they absorb water like a sponge and have a porous and irregular surface (under magnification) that contributes substantially to evaporation.

    Paul - the chemical reaction you're describing is electrolytic action/reactivity or galvanic corrosion. Aluminum is particularly susceptible to this reaction when in direct or electrical contact with other metals.

    Al

  • MsGreenFinger GW
    9 years ago

    Clay pebbles float so you can't cover them with water, no matter how much you pour in the tray.

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    MGF - the ones you buy float? I'm curious if anyone stateside has encountered a product like that?

    Anyway, we don't want them completely submerged, and even if they floated, they wouldn't float completely above the water. A fraction (say about 50%) would still be submerged in water, and capillary attraction would wet the remaining above-water surface - making the arrangement about equal to clay balls half submerged that didn't float.

    Al

  • ellenr22 - NJ - Zone 6b/7a
    Original Author
    9 years ago

    Paul: yes, and my aluminum trays are from the dollar store; I know from experience they have a limited life.
    I will have to watch carefully, to prevent spillage all over the floor.
    but for as long as they last, this is a very convenient arrangement. Instead of each plant having its own pebble tray, I have 5 small and one mid-size plant on a tray. So have only one to keep filled, and takes less space. and it doesn't look as bad as I thot it might, the plants direct one's eyes away from the aluminum.
    I could get one of those roasting pans that are not aluminum, which would look better and last longer.

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Stopping at a garage sale every now & then will yield a lot of containers suitable for a variety of chores related to our plant hobby. Glass and aluminum pans, as well as containers well suited to be pressed into service as pots are usually bountiful, based on what I've seen.

    Al

  • queen_gardener
    9 years ago

    great thread
    I use a plastic serving tray I got on clearance at the dollar store and I lined it with small pebbles - it's working perfectly! I don't have trouble balancing pots on the pebbles, as they are very small.

  • MsGreenFinger GW
    9 years ago

    Al
    I've tried 2 different brands so far and they both float. At the moment I have a bucketful of them soaked in water for about 5 days now and about 90% is still on the top.
    I thought this was their normal behavior.

    As a pebble tray I use cat litter trays (2 for â¬1.50). Plastic, easy to clean and the perfect size to accomodate about 4 plants each. Very handy for me as reservoir.