Build a Sprouter





Build an Automatic Bean Sprouter And Misting Sprouter


"Our daily paper would surprise us if it carried an ad: `Wanted, a vegetable that will grow in any climate, rivals meat in nutritional value, matures in three to five days, may be planted any day in the year, requires neither soil nor sunshine, rivals tomatoes in vitamin C, has no waste, can be cooked with as little fuel and as quickly as a pork chop.' The Chinese discovered this vegetable centuries ago in sprouted soy beans. Today they are an important food for many millions."

Clive McCay, Cornell University 1943

Fatbean Sprouter:



The Fatbean Sprouter is a simplified and improved version of my Automatic Sprouter that has been in continuous use since 2011. The inspiration for this design comes from “The Sprouting Book” by Ann Wigmore.

Existing commercial home sprouters don't provide pressure for the growing bean sprouts, or a simple way to trim the root hairs. This sprouter is made up of an upper Growing Chamber nested into a lower Plumbing Chamber. This design allows the Growing Chamber to be quickly inserted and removed without the need to deal with the plumbing. Once set up, the Plumbing Chamber can be left connected to the water supply and drain. The resulting bean sprouts are straight, tall, plump and happy. The fine root hairs grow naturally downward into the root blanket, made of Rockwool fibers. Most of the root hairs can easily be cut off when you harvest the sprouts.

Rinse water is supplied by the programmable water valve timer. It is programmed to supplies 2 min of flow every 4 hrs. A garden hose adapter connects a 1/4 inch polyethylene tubing to the sprouter through a ball valve. You can operate multiple sprouter by simply adding a tee fitting and ball valve for each sprouter.

The outer Plumbing Chamber is a modified 1 gal Sterilite plastic pitcher. The sides are cut to allow the Growing Chamber to tilt into the Plumbing Chamber. A drain fitting is placed at the bottom of the chamber. Supply water is plumbed into the top of the chamber through a bulkhead feed-through union. A 5” perforated tube directs the supply water downward onto the porous weight. Water diffuses through porous weight rinsing the beans sitting on the root blanket.

The inner Growing Chamber is made of another 1 gal plastic pitcher. There is a hole cut in the side of the chamber at the height of the water supply feed-through. The bottom of Growing Chamber is perforated to allow water to drain.


 Fig 1. Sprouter with finished Mung Bean sprouts


Porous Weight:

The porous weight is made by combining 2 lb of 1/8” to 1/4” washed crushed stone with just enough clear epoxy to thinly coat the stones. It's important that epoxy does not run down the stones and clog the spaces between stones. Cut a 20” length of 1/4” fiberglass rod. Drill a small hole through the rod  near the end of the rod and insert a 3-4” cross piece of plastic. This will prevent it from pulling out of the stone weight. Drill a 1/4” hole in the center of the pitcher cover.

Spray the inside of the Sterilite gallon pitcher with non-stick cooking spray. This is a mold release agent for the weight when the epoxy sets.

Mix equal parts of epoxy and hardener to make 2 oz (6 Tbs) in a disposable paper cup. Place the 2 lbs of crushed stones in a 1 gal zip lock bag. Add small amounts of epoxy to the bag and mix thoroughly. Add just enough epoxy to just coat each stone, but no more. You will need to mix a long time to distribute the epoxy evenly.

Pour a 1/2 inch layer of coated stones into the bottom of the pitcher. Tamp the stones down to level them. Be sure to to fill the corners. Insert the 1/4” rod, cross piece down, and center it on the stones. While holding the fiberglass rod upright pour in the rest of the coated stones. Tamp them down to level. Be sure to pack the stones around the rod and into the corners. Install the cover on the pitcher to support the rod to keep centered and vertical, until the epoxy sets. The rod will keep the weight level when the beans start to push up. Allow the weight to set at room temperature for 24 hrs.

After 24 hrs, lightly tap the outside of the pitcher to loosen the stone weight , and carefully lift it out by the fiberglass rod. Wash the oil out of the pitcher and weight with hot water and dish washing liquid.

porous weight molede in the 1 gal pitcher(1)

Fig 2. Molded Porous Weight in 1 gal pitcher



Root Blanket:


The root blanket is a 5 1/2” circle x 1” thick disk cut from Grodan Stonewool. This material can be sliced with a bread knife. I cut 6” x 6” squares, from the Grodan block, them slice three 1” squares. Mark a 5 1/2” circle on the face of each square. You can make a cardboard template. I made a round cutter by purchasing a 6” drywall hole saw and grinding the teeth down to a knife edge. You don' t need to get that crazy. It is ease to cut with a serrated bread knife.



Fig 3. Cutting the Root Blanket



Plumbing Chamber:

The lower chamber provides a spray of rinse water in at the top, and a drain at the bottom. Water is sprayed down from a short piece of perforated poly tubing.

Use a fine tip felt tip pen to draw a vertical line on the outside of the chamber 25 degrees clockwise from the middle of the handle (top view). Make a dot 1 1/8” down from the top of the chamber. Use this dot as the center of a 5/8 ” hole for the bulkhead union. Always work in a well ventilated area. The fumes from the melted plastic are toxic. Mark a second center 3/4” up from the bottom of the vertical line. Make a 1/2” hole, be sure that the plastic drain fitting nut clears the corner of the chamber.

Draw 4 vertical lines at 100, 120, 260, and 280 degrees. Draw a horizontal line 3 3/8" above the bottom, between the 120 and 270 degree lines. Use a flexible ruler to draw a line from the junction at 120 degrees to the top of the 100 degree line. Do the same on the other side. Draw a line from the junction at 260 degrees to the top of the 280 degree line. Use a hot blade to cut away the section of the pitcher. Clean up the edges of the cut with a sharp knife. You can flame polish the edge with a propane torch. Clean the felt pen lines with alcohol.

Install the through wall feed through fitting. Install the bulkhead hose barb fitting at the bottom of the chamber with the rubber seal on the inside.


pitcher with lines drawn

 Fig 4. Plumbing Pitcher with lines drawn


plumbing chamber

 Fig 5. Assembled Plumbing Chamber


Water Supply Tube:

Heat the end of a length of 1/4” polyethylene tubing to soften the plastic. Squeeze the tip of the poly with a pair of pliers, fusing it closed. Hold it closed until it cools. Use a candle to heat a needle to melt an array of holes in the bottom 20 degrees of the poly tubing. The holes should be only 4” from the capped end. This will distribute the supply water evenly onto the porous weight without to much water dribbling down the side walls. Cut the poly tube  off at 5” from the capped end. Insert the tube into the inside feed-through fitting. Rotate the tube so that the holes are facing down. Heat and bend the tube horizontally 5 degrees or so. This will avoid a collision with the center rod. Mark the top of the tubing with a felt tip to make alignment easier.

Water supply tube with needle

 Fig 6. Water supply tube with needle and bulkhead feedthrough


Growing Chamber:

Use a felt tip pen to mark the top rim of the pitcher 155 degrees clockwise from the center of the handle. Draw a vertical line from the mark to the base of the pitcher. Mark a center 3 1/4” down from the top. This should be the center of the bulkhead union in the Plumbing Chamber when they are nested together. You can temporarily remove the feed through union on the plumbing chamber to confirm the correct position of the center. Make another mark down 5 1/4”. Use the soldering iron to make a 1 1/2” round hole in the side of the pitcher. This will allow clearance for the water supply feed-through union. Cut a 1/4” slot down from the hole to the 5 1/4” mark. This slot is to allow the water supply tube to slip into the chamber

Use the round tip soldering iron to punch vent holes just below the outside ridge of the chamber. Space them about 1/2” apart. Use the hot iron to make holes every 1/4” on the the bottom of the chamber, and a 1” hole in the center. This will provided good drainage and be able to support the root blanket, beans, and porous weight.. Remove the hinged cover on the pour spout. Cut off the two plastic bumps on each side. Cut a 1/4” slot from the center hole to the pour spout opening. Insert a root blanket disk and press it down to the bottom of the chamber. Temporarily place a 1” thick spacer on top of the root blanket. Insert the porous weight and put the cover on the chamber. Cut the fiberglass rod off at a length that will position the knob at the level of the cover. With the spacer removed, there should be an air gap between the blanket and the bottom of the porous weight. This will allow the sprouts to get started before they have to endure the pressure of the 2 lb weight.

Fit the Growing Chamber into the Plumbing Chamber. There should be a 2” air space between the between the chambers.

 Growing Chamber with Cover

Fig 7. Growing Chamber with cover


 Growing Chamber bottom view

Fig 8. Growing Chamber, bottom view



Fig 9. Growing Chamber with Root Blanket, Spacer and Porous Weight



Programmable Water Supply:

Water is supplied from a Garden Hose Fitting. Typically available from a basement sink or Washer cold water tap. Install a garden hose splitter with a valve for each leg. Next a battery powered programmable garden hose timer is installed. It should be programed to  turn on the water for 2 min every 4 hrs. An inline valve is installed near the sprouter to regulate the flow.

Programmble Water Supply(1)


 Fig 10. ProgrammableWater Supply with Hose Spliter



Connect the water supply and drain tubes. Place a 5 1/2” Root Blanket disk into the bottom of the Growing Chamber. Be sure it's level. Run water through the root blanket for 5 minutes to wash out any rock dust in the rockwool. Place a thin layer of pre-soaked organic sprouting beans on top of the Root Blanket. Spread out the beans evenly. Don't allow more than 2-3 bean thickness. Install the porous weight and the cover. There will be a gap above the beans.To get fatter, cruncher sprouts, you can place an apple on top of the weight. The apple supplies ethylene gas to the sprouter.

Tilt the Growing Chamber into the Plumbing Chamber. Carefully align the keyhole slot in the Growing Chamber with the Water Supply tube. The tube should be inside the Growing Chamber with the needle holes facing down.

Cover the sprouter to keep it in the dark. Don't block the air. Start the Water Timer program to spritz the beans for 2 min. every 4 hrs. That's it. Just watch and wait until harvest time.


Fig 11. Growing Chamber with Beans, air space and Porous Weight


 use assembly(1)

Fig 12. Complete assembly ready to use




The sprouts should reach 2-3 “ length in 4 to 8 days, depending on the type of bean and the temperature.

Close the ball valve and tilt out the Growing Chamber. Remove the cover and porous weight. Push the Root Blanket disk up from the bottom of the chamber. It will push out the solid plug of densely packed bean sprouts attached to the Root Blanket. Use a long sharp knife to separate the Root Blanket from the sprouts. Most of the root ends will be cut off with the Root Blanket. Use water bath to separate the sprouts from the seed coats. Break up the used root blanket and toss it in your compost bin.

It is very important to clean and sanitize the sprouter. I use a 10% bleach solution in a spray bottle. Spray the sprouter with the bleach solution and flush everything with clean water. Allow it to air dry before storage.


 Fig 13. Finished Sprouts


Removing the Plug(1)

Fig 14. Push out the plug


Cutting the Plug

Fig 15. Cutting the sprouts from the Root Blanket




soldering iron with 1/8” tip, Xacto X73789,                $ 12.68

soldering gun with blade tip,   Weller WEL 8200PK Kit                    $ 44.00

heat gun Wagner HT1000,           Home Depot                                  $ 22.96


candle                                                                                                      $ 0.25

drill with bits                                                                                         $ 45.00

dissecting needle with handle ,                                $ 0.50



Easypower 6”hole saw                                                   $17.00

(modified,make toothless)

compass 6” printout




2 Sterilite Plastic Round Pitcher – 1 gallon,   Walmart                     $5.76


25 ft Polyethylene Tubing – 1/4” O.D,                3.00

1/4” - 1/4” push to connect ball valve,    Fire & Ice                           $4.95

1/4” through wall union ,                               $4.47

3/8” hose barb bulkhead drain, PHBBF-3/8,,         $ 1.98

Grodan Stonewool Expert Slab, 6 x3 36”,  $ 7.50

10 ft 3/8” I.D. Clear vinyl tubing P3/8x5/8,             $ 0.40/ft


Melnor Aqua Timer Valve Water Timer,        Home Depot              $ 30.00

Garden Hose Female to 1/4 tube,                   $ 4.00

1/8-1/4” washed crushed stone,                        Petco                           $ 3.20

Clear Epoxy Resin,                                                 $ 11.14

1/4” fiberglass rod cut to 20”                           $ 4.80


1" knob, .25" shaft, #264955                                       $1.00





Fig 16. Finished de-hulled bean sprouts                                           








Add A Misting Sprouter


To sprout leafy greens, such as alfalfa,broccoli, and radish,you can build your own misting type sprouted. This design is derived from the GoGreen Sprouter designed by Val Archer:



The misting kit is available from New Life Solutions LLC. They also sell the assembled sprouters, and all the extras you may want.



Or you could, just buy the misting string (Orbit 20066 Outdoor Mist Cooling System and shop around for the rest of the plastic plumbing.



The programmable water supply valve is the system described in my Bean Sprouter. I simply added a tee and shutoff valve to my Sprouter. I can run both Sprouters at the same time. 


      I started with a Sterilite 66 Qt. Clear View storage container, Sterilite model Clear View Latch . It's important that you find a container with a clear cover. I purchased the basic mist kit from GoGreen. I used a hot soldering iron to cut out the holes in the plastic. Do this in a well ventilated area. Make the holes for the water inlet elbow fitting, and the bulkhead drain. The size of the hole will depend on the fittings you use. I made 5/8” holes at the bottom corner of the end of the container, and 3” down from the top rim. The top hole is made in the end of the container. This is where the water supply tube is inserted. I cut a 5” x 3 3/8” rectangular holes in the lower back of the chamber, and in the center of the cover. These holes will accept the Easy Change Bio Filter Cartridges . I used these filters to allow good ventilation without allowing dust or bugs to get in. They are attached to the container with double stick foam carpet tape. The lower edge filter hole should be 1.5” above the floor of the container I had to add a baffle to deflect dripping water from leaking through the lower vent.


                     Misting Chamber with Slooping Plexiglass sheet


My growing trays are plastic Kitchen Garden Seed Sprouter Trays. I had them so I used them. The inner plexiglass sheet is cut to fit into the container tilted at around 30 degrees. I made a cardboard template to determine the shape. Its not so easy. Locate two Nylon spacers for each Sprouter Tray to position the trays at the top of the slopping plexiglass sheet. The Spacers are pushed into holes drilled into the plexiglass sheet. The finger hole makes it easy to remove the plexiglass sheet for cleaning.


                            Misting Chamber with Sprouting trays

The Nozzles are arrayed along a line 3” below the top on the container. I staggered nozzles opposite sides on the container to avoid interference. The nozzles are tilted down a bit to give uniform coverage of the trays. They are held in place by cable ties and adhesive backed cable tie pads. Be sure the surface is clean and dry.



            Top View of Misting Chamber, with mister tubing and misting nozzles

A 22” Grow Light is mounted 6” above the center of the cover.  Connect the Light to a programmable timer. I use 10 hrs on, 14 hrs. off.This will provide enough light to green up your sprouts.



                      Fig4: A Good  Sprouter In A Rough Location



     Sterilize the sprouter before use. I use Bleach ( 1tsp per pint of water) in a spray bottle. I spray everthing inside the sprouter, then rinse with clean water. While the sprouting tray is wet, I sprinkle the seeds evenly in the tray. Don't pile them up, they need room to breath.Close the cover, open the water shutoff valve, turn on the grow light timer, and start the water valve program. Keep the temperature around 70 deg F.That's it. Harvest your sprouts when they get big enough.





20'  1/4” Polyethylene tubing,  $.17/ft                    $3.40

20' 3/8” Clear Vinyl Tubing,   $.33/ft.                    $6.60

1757 Clear View 66 Qt. Polyethylene Storage Container, Target                   $10.00

 1/4" Tube O.D. Union Tee,  US Plastics                $2.29

1/4” Speedfit® Polypropylene Shut-Off Valve 1/4",       $5.18
1/4" Stem O.D. x 1/4" Tube O.D. Plug In Elbow,    $1.64

 1/4" O.D. Union Connector,                              $1.60
GoGreen Basic Mist Kit    $89.00

          Includes;Tubing, Mist Nozzles, Fittings, Drain Fitting, Instruction CD

1/8” Barbed Nylon 90 degree Elbow pkg of 25                  $1.60

Nylon Adhesive Backed Cable Tie Mounts size, pk of 50  $3.00   

Nylon Cable Ties 4”, pkg of 100                                      $2.30

DT121C Intermedic 24 hr. programmable timer                $18.00

GLS9721 Good Earth Grow Light,                                   $11.70

Easy Change Bio Filter Cartridge 3 3/8” x 5” 2                                               $6.00