Buckets + bark - compost? Peat? Calcium Carbonate grit?

Everett, WA(Zone 8a)

I was setting up some buckets for tomatoes using a lot of small bark nuggets and some bark fines to assure fast drainage and aeration. I plan to use drip emitters and mainly fertilize with soluble Miracle-Gro, but probably mix some granular fertilizer in with the bark.

I'm new to tomotoes in buckets, but I tend to overwater things in containers. Hence the bark nuggets. I'm using some chunks that pass through 1/4" screen, and all pass through 1/2" screen. I'll try to remove the remaining bark dust, but then I need to add something fine for wicking and some water retention.

Can I add my own compost so my soiless mix isn't "soulless" ? What would be the limiting factors on adding compost to a bucket. I'm thinking of the very finished, fine black stuff that filters out the bottom of the pile.

I figure the livng populations added might be welcomed by the roots. I realized that the mix I had planned would have been pure hydroponics, and I don't necessarily want to avoid soil ... but neither do I want my buckets to turn into mud pudding..

(I planned to water once per day with drippers and a timer, but could water twice per day as easily).

Or, I have plenty of bark and coir fines and had planned to add a little of them for wicking. Maybe skip the compopst and stay with a 100% soiless mix?

Is there any big advantage to buying a bag of peat-based potting mix, instead of using bark fines? I assume any commercial mix will hold more water than bark fines would.

In the past, for starting seeds, powdery peat mixes have killed me with my tendency to over water: they suck up and hold all the water in sight, become totally sodden, never drain through, and drown the roots. But I plan for the fines + compost + peat mix to total no more than 10-15% of my mix, so that should not happen.

Other questions:

1. Is it a mistake to try to mix a little granular fertilizer in with the soiless mix? Generic lawn or garden fertilzer, like 16-16-16.

2. I thought I was buying a bag of crushed GRANITE grit (#2 chicken grit), but they gave me the Calcium Carbonate kind. Crushed oyster shells? Two Master Gardeners told me that "Calcium CAUSES BER". OK, searching here, I see it neither causes it nor cures it, BER is probably poor distribution of Ca++ inside the plant. So they were NOT 'Mater Gardeners.

However, since I have it, and it is coarse, is mixing 5-10% crushed oyster shell into the mix too much calcium for tomatoes? I figure that chemical fertilization is likely to increase acidity over time, and why not limit that increase? I don't know what pH oyster shells tend to buffer towards - might it be too basic for tomatoes? I read they like to stay below 7. Should I go very light on that kind of grit, or just not use it for tomnatoes at all? I can always spread it on raised flower beds. And I have saved some crushed stone that has been sitting outside for over a year, I could use that.

I know it is late in the season in most regions for getting plants into the ground (or bigger buckets), but nights were below 50 until fairly recently. These have been in one gallon buckets on my deck for several weeks.

Hornell, NY(Zone 5a)

Rick, you can buy really good potting mix for about $10-15 a bag that will solve most of your tomato planting problems. The mix will not sog out if there are holes drilled in the bottom of the container. Your fertilizer should be okay if used in moderation. A handfull of pulverized garden lime would be good also, might prevent the dreaded blossom end rot problem so often seen in container tomatoes. If you're dealing with tomatoes, keep in mind that they are very thirsty plants, especially during the blossom and fruit set time. Larger containers work better than small ones. Using dwarf varieties helps also.

I don't know where you're going to find healthy transplants this time of year. Might be easier to start this project in May.

Good luck.


Saylorsburg, PA(Zone 6a)


Instead of peat you might consider using coir and adding perlite which prevents compaction of the soil. Somewhere on DG someone suggested this composition which I used this year in my coir bags for tomatoes and eggplants with great success: 1 part compost or manure (I used rabbit manure and mixed it with bagged compost), 2 parts coir or peat moss, 1 part perlite or vermiculite (I believe this holds water whereas perlite releases it). I mixed all that with a general organic granular fertilizer (Espoma is good), some bone meal and rock phosphate. I could have added lime but I use an organic spray system (Aggrand products - www.aggrand.com/ which includes bottles of liquid lime and a liquid kelp (potassium). The plants in my coir bags are doing even better than the ones in the ground or straw bales since it is easier to regulate the water. When they begin to dry out I add the water. During the heat waves I put wet straw on top to hold in the water. The same should apply to buckets as you planned.

Everett, WA(Zone 8a)

>> I don't know where you're going to find healthy transplants this time of year. Might be easier to start this project in May

It sure is late in the year! But I have had 6 Sungold plants growing in 1 gallon buckets since evenings have been cool (instead of cold). 4-6 weeks? I'll wince when I strip the few flowers as they go into bigger buc kets.

>> you can buy really good potting mix for about $10-15 a bag

That is what I'm trying to avoid. Using mostly bark at $4.25 per 2 cubic feet sounds nice to me, no matter how much screening and fussing I have to do. And I know I will have better drainage with 85-90% bark plus 10-15% compost or commercial mix, than I would with commercial mix alone.

I'm willing to believe that the peat-based mixes I have tried up to now were simply all crummy rip-off products. The wholesale nursery supply place I found certainly does not stock any brnad I saw in Home Depot!

And buckets may be less sensitive to over-watering-drowning than seed flats. But I want to see some water come out the bottom, when I pour enough onto the top!

For sure you know very effective ways to grow tomatoes! And buyin g the potting mix would be much easier and faster than making my own. But a large part of my interest in plants is in cultivating the soil, or even more CREATING the soil.

Everett, WA(Zone 8a)

>> Instead of peat you might consider using coir and adding perlite which prevents compaction of the soil.

Using at least 80% bark nuggets should give me plenty of drainage and aeration. I won;'t need to worry about compaction of the small amount of compost or fines or commercial mix: rather IK should worry about it washing out from between the nuggets and out of the pot, or packing all togther at the bottom of the pot.

I think the mix you described is very fine whereas mine will be very coarse. I just need to add SOME fine stuff to mine to give the root hairs something to grab.

>> general organic granular fertilizer (Espoma is good), some bone meal and rock phosphate.

I might splurge on a small bag of organic fertilizer, but if I go in that direction I would probably rather use my own compost. I'm sure the idea of slow-release and low-intensity fertilizer is safer, but "a little chemical fertilizer" may be OK. 16-16-16, not urea (highly soluble 46-0-0, a.k.a. "burn those roots on contact!").

And I'll buy some dolomite lime. Someone else pointed out that CaCO3 from crushed shells may be salty, or pull the pH too basic.

Omaha, NE(Zone 5b)

Rick, you might consider using an "earth bucket" approach. I made seven that I've been using for 5 seasons now.

A little more work up front, yes; but (properly used) impossible to over-water.

Thumbnail by RussMartin4154 Thumbnail by RussMartin4154 Thumbnail by RussMartin4154
Everett, WA(Zone 8a)

I like the idea of internal reservoirs and a soiless mix that wiull "wick", but was always dubious about planning to flood several inches at the base of the bucket. Won;'t any ropots that go that deep drown as often as you add water?

My thoguht was that you also can't overwater if the mix drains well.

So far I've been able to get buckets for free, or use buckets that had cracked or leaked. Thus even a colander would be "a big invetment" compared to nothing. Some year I might try that as an experimentg. Do Dollar SW tores have 99 cent colanders strong enough to support the soil?

I have played with the idea of a "cheapo earth bucket". Use the bottom 3/4" or 1" of the bucket as a reservoir, by drilling the lowest row of holes a little above the bottom. Supplement my bark nuggets' wicking with some small cotton wicks. Trust that the entire root ball plus wicks will pull the very shallow "reservoir" water back up into the aerated part of the bucket fast enough that no roots drown.

However, if my timer can water twice per day, isn't that enough that I need no reservoir? These plants won't get huge, they will only have a few more months of growing season, or rather "warm enough to ripen fully" season.

How do real earth buckets deal with periodic flooding of part odf the root zone

Omaha, NE(Zone 5b)

Rick, if you look closely at the first photo (repeated here), you'll see a couple of small black circles drawn in. That's because others have asked some of the same questions. The circles show one of two overflow drain holes on each bucket. The reservoir can never fill above those holes.

The "wick" is a quart plastic paint cup with slits cut in the side. It doesn't need to support any weight because its bottom rests on the inner bottom of the lower bucket. I've also seen this done with red Solo brand plastic drinking cups.

Part of the "physics" of the system is that the mix in the upper bucket never be allowed to go dry. The easiest way to ensure this is to fill the bucket(s) daily. However, if one does go dry, it's a simple matter to fill (slowly) from the top, next to the plant, until water runs out the overflows.

At first, when the plants are small, it takes very little water to top them off. When the plants are large and leafy, and the weather is hot and dry, transpiration will nearly empty the reservoir in a day.

Thumbnail by RussMartin4154
Charlotte, NC(Zone 7b)

Rick -here's link that you might find helpful


I think this is very similar to Russ's set up

Omaha, NE(Zone 5b)

The "Global Buckets" site wasn't around when I started looking around 5 years ago, so I worked from this:


There are only a couple pages (17-19, I think) dealing with nested 5-gallon buckets, but that's where I started.

This message was edited Jul 29, 2012 2:43 PM

Vista, CA

i use drip emitters and where my soil is sandy or has above average drainage, the moisture from the emitters does not spread very well. So if you are using soil like you are describing, you should perhaps consider the little spray heads that will give a wider wet area than just a drip emitter.


Everett, WA(Zone 8a)

I see the PDF that shows a central wick, like a Solo cup filled with soil, and slit sides. That does look cheaper than an inverted colander. If I like the idea of veryh water-holding, wicking soilless mix, that would be a way to gol.

But indeed I will have something more like sandy or even gravvely mix. I recently bought one cubic foot of commerical "peat mix", and one cubic foot of compress sphagum peat, to be 10-20% of my mix, for wicking and water retention.

Ernie's point is well taken - I might use shrubblers to spreade the water around. Or 2-3 small emitters, along with 15% peat, might distrbute it enoguh.

Sierra Foothills, CA(Zone 8a)

Corey ~ OK, now, what have you done so far? And how are your tomatoes doing now? It is definitely a better year for tomatoes, weather-wise, though I put mine out late as well. I will have to take some pics and post them to you. I have some in SFG beds, some in pots of various sizes, and a few in the ground, though the gophers ate most of those.

Everett, WA(Zone 8a)

Well, more home tasks came up, including visits from someone that I CLEAN THE HOUSE for, so a lot of time went there.

I knew that hours spent on real soil would pay back fatser than making up the buickets, and I had one bed pooped out, so I put half the seedlings (now 2-3 feet tall with blooms and green marbles) into soil in a riaqsede bed. Improved that soil a lot, with composted manure, coffee grounds and screened half-done compost from my heap (humus and some fine wood fibers).

Fulfilled a dream I've had for decades of setting up drip irrigation for uniform mositure. (dripline)

Thjree days later, we had one night6 go b elow 50 and average temps are dropping steadily.

The next part of The Plan was a plastic tent or hoops tall enoguh to keep adult toms warm enough to ripen tastily ... ... maybe next year.

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