Experimental Design : Gravel

Gravel with Screen
A reader, Pete Sims, has a clever idea for a one-bucket design. We've asked Pete to send us some pictures of his setup. If you've used a similar design please let us know and we'll post your ideas. Pete writes...

1) Make a mark on the inside of the bucket all the way around at 12" from the top

2) Place a tin can with holes punched into it and place it in the center of the bucket

3) Make sure that you have your input water hole/line and your exit water hole/line installed (if you are connecting in series), before you go to the next step

4) Fill the bottom of the bucket with gravel that is maybe 3/4 to 1 inch in size all the way up to the mark on the bucket

5) Get a piece of screen or material that will let water through and place it over the gravel with a cut out for the tin can

6) Now you can fill the bucket with potting mix and plant the same as usual.

You can easily adjust your water level by either raising or lowering the float valve or the bucket. This method as you can see utilizes one less bucket and at the same time uses a product that is found worldwide, gravel!

Lessons Learned, Advice and Comments from Readers

Red Party Cups
In our video, BUILD a Global Bucket, we're using 18 oz Kirkland Chinet Premium Heavyweight plastic cups purchased from COSTCO . The 3 1/2" hole saw makes a perfectly sized hole for the 18 oz cup. A 16 oz cup should work fine, but you'll need a smaller hole saw.


"Food Grade" Buckets
A reader wondered if the possibility of plastic leaching from a bucket is a health concern. We do not express any opinion on this question, but if you do have concerns you may want to use "food grade" buckets (buckets that once held food in them).


Irrigation and Root Disease
A viewer from YouTube (jj8a) questioned if root disease could transfer from one bucket to another bucket via the 1/4" tubing in the automatic watering system. This is a great question. To be honest, we don't know the answer. We don't think water or a disease would migrate from the end of one tube in the bottom of one bucket back into the 1/4" tube and then into the main 1/2" line. Why? The siphon is "pointing" away from the 1/2" line towards the bottom of the bucket. It's a one-way force. Perhaps to be on the safe side, we should eliminate the optional "T" in the 1/4" line that feeds two buckets from the 1/2" line. If you're an expert in agriculture who appreciates the siphon's one-way force we would love an expert opinion. Thanks!


Avoid Mosquitoes
The water refill pipe should be covered or capped. In tropical climates, the opening will invite female mosquitoes to breed and consequently diseases such as malaria or dengue could spread rapidly. (from YouTube viewer "asanov" writing from Malaysia)
Editor's Note: Shouldn't be a problem if you're using our automated watering system as seen in the videos.

Use Level Ground
If you're using our automated watering system (see the videos) make sure the buckets are on the same level ground as the reservoir. We had our buckets and reservoir on a sunken patio which had an "invisible to the naked eye" 1/4" per foot drop. The main reservoir was eight feet south of the buckets. This resulted in the bucket's water level two inches too low. Ooops!

Float Valves
This is where we buy float valves: US Plastic Corp
Make sure you get the adjustable valve. We upgraded from the 1/4" to the 1/2" because during the summer the plants were drawing a lot of water from the yellow reservoir and it appeared that the 1/4" valve couldn't keep up with the demand.

Renewable Peat?
"Just so you know, the 'traditional' thinking has been that peat bogs take 10,000s years to form. I have seen college text books that teach this. However recent research has found that Sphagnum moss grows up to 30 inches tall each year. I own 150 acres of forestland which includes peat bog. I can harvest peat, and it does grow back. Allowing re-harvest every 8 years. If I remove a 3 foot thick layer of peat, and come back 8 years later I can do it again. Peat is a renewable resource. Northern Scotland, Ireland, and Finland have been performing renewable harvests of their peat bogs for about 30 years." Galen Young of Argyle, Maine.

Dolomite

Probably the most confusing material is Dolomite. Often it's not labeled as Dolomite, but don't give up, you can find it if you look a little. Dolomite is commonly sold in garden or farm stores.

Dolomite is added to the potting mix to:
1) adjust the pH : it lowers the acidity ("sweeten")
2) add magnesium (important!)
3) add calcium (important!)

Key Points When Shopping for Dolomite:
-Often the bag will NOT say "dolomite"

-It might be labeled as "Agricultural Lime", "Agricultural Limestone" or "Garden Lime". Check the ingredients label. It must have CALCIUM & MAGNESIUM.

-"Agricultural Lime" and "Garden Lime" are broad terms. Just remember, if it doesn't say calcium, magnesium or calcium/magnesium carbonate or some variation of this, then it's not dolomite.

-"Hydrated Lime" is not dolomite. Hydrated Lime is highly concentrated, highly caustic and dangerous to handle or breath. Also, it contains no magnesium.

-Any bag of "lime" labeled "DOLOMITE" containing calcium and magnesium is suitable.

-Dolomite can be sold in finely powdered, pulverized or pelleted form. Buy the powdered or pulverized and avoid the pelleted form. The finer the dolomite is ground, the faster it becomes available to the plants. Talcum powder fine is best.

-Price: For a 50lb bag the cost should be US $4.00 to US $6.00

-Acid loving plants, like strawberries or blueberries, only need 1/2 cup or less.