How To Build Your Own Strawberry Tower

By popular demand, here's a video detailing how I build my strawberry towers. I hope you find it helpful! Full transcript is below. Click on the video image to watch in HD!

Hello everyone.

One of the top requests I get is how to build a strawberry tower. This video will display all the necessary steps to build your own.

The first step is to place a mark on each end of the pipe, then rotate it 180 degrees and mark the other end. Then snap a line down the entire length of the pipe. You could also use a straight edge to mark a line, but I find the chalk line to be more accurate and easier. Turn the pipe over and snap a second line down the opposite side.

Along each chalk line you will place a series of marks. Starting at 2 inches, draw a mark every 8 inches. This will be the spacing between each pocket in the tower. If you are going to grow plants that need more root area, set the spaces further apart. I typically replace the strawberry plants every season. If they grow for more than one season, they can become root-bound.

Starting at the first set of marks, draw a line from one mark and connect it to the mark on the opposite side. Then turn the pipe 180 degrees and connect the next series of marks. Continue rotating the pipe while connecting each series of marks. These lines will be used for cutting the slots in the tower.

Along each cut mark, carefully cut through the pipe until you reach the measured mark you placed at the chalk line. Do not cut through more than half the pipe! Rotate the pipe 180 degrees and cut the next slot. When you are done, each slot should be on the opposite side of the previous slot.

Time for some good gloves. The pipe doesn’t become flexible until it is well above the boiling temperature of water. Please be careful!

The general area that will be heated will be an arch shape starting at one end of the slit, up about 8 inches to the back side of the neighboring slit and then back down to the other end of the slit.

Heating PVC should be done in a well vented area. If you overheat it, it can release some nasty gases. Please be careful! Continuously move the heat around the arched area. Try to avoid heating the area below the slit to keep the pipe from bending too much.

After a few minutes, the PVC will become soft. It helps to apply a little extra heat at the each edge of the slit since this is where the sharpest bend will be.

Push in the PVC so it makes a concave shape in the arched area. You will want to push it in enough so that it will touch against the back wall, but not create a seal since the water will need to trickle through that area, but don’t leave too big of a gap so your growing media will fall through it. When you let go of the pipe, it will usually spring back a little, leaving a gap around ¼”.

I found it to be very helpful to use a few spring-clamps to hold the tight bends in place while the plastic is cooling. You will want to hold the shape in place for a couple of minutes while it is cooling.

It takes me about 3 1/2 minutes to completly create each pocket.

When you are done, you will have some nice pockets alternating on each side of your new tower.

As the water flows through the tower, the surface tension in the water can cause it to flip out of the edge of the slit. To correct this, I added a collar around each pocket.

With some extra pipe, cut some rings about 1 ½” wide. Then remove enough of the ring so when it’s placed over the slit area, it extends just beyond the slit. Add some silicone adhesive and clamp the ring in place. Half of the ring should be placed above the slit line. Use clamps to hold it in place until it cures.

If you’re not going to be draining directly into a sump tank, you’ll need a way to catch the water from your towers. Take a 4” cap and add a fitting to it. Drill a 7/8” hole and thread it with a ¾” tap. There are several ways of adding fittings, but I found this to be very cost effective method.

Take a ¾” NPT to barbed fitting and screw it into the tap. If it is screwed in far enough, it will be higher than the base of the cap. This work well to help any media that as fallen through from going down the drain and clogging it.

This cross-section shows how the fitting is placed into the cap.

Place the cap on the bottom of the tower. The bottom pocket should not be filled with anything so you can clean the base cap if necessary.

To hang your tower, drill a couple of holes on both sides near the top and insert some S hooks. Use a wire or chain to hang it from a strong support.

To connect the tower drains together, you can attach them with tubing and barbed fittings. I made some stands from scrap 3” pipe to support the bottom of the tower. Then I used a 1-1/2” pipe with holes drilled in the side to catch the water from each tower. Each pipe then drained into the main sump tank.

Filling each pocket can be a challenge so I made a tray-type funnel to speed up the process. Take a section of pipe and do a cut down its length. Heat the entire piece so it can be flattened, then bend up the edges so it forms a V shape.

I created a cross-cut section so you could see the inside of the tower. Please note that this sample is done with black ABS so you could see the various surfaces easier. Each pocket will hold about 5 cups, or 1 liter of growing medium. This is enough space for most shallow root plants like strawberries or lettuce. For my strawberry plants, they will usually get water for 10 minutes every hour and a half.

Thank you for watching. Here’s a quick slideshow of my strawberry towers in action!

Plastic Extruder for Growing Media

For several months, I’ve been developing a plastic extrusion system that has been able to take virgin HDPE resin pellets, or shredded milk jugs, and properly melt and extrude them into a shape that could be used as a low cost growing media for my Aquaponics system.

There was a lot of trial and error to get to this point. The biggest problem is that the plastic retains little moisture. If the seeds aren’t directly placed in the flood/drain cycle, they won’t get any moisture to germinate. I typically grow in stone and some of the stone above the water line is able to wick and retain enough moisture to provide water to new seeds.

Another issue with HDPE is that it’s extremely smooth (again, works well to repel water). Even adding texture to the media during the cooling process, the media still is smooth, which makes it difficult for bacteria to stick to it. I was also a bit surprised to see that the roots didn’t really care to grow in it and they would grow around the edge of the net pot instead.

On the plus side, the plastic is light, fairly inexpensive, clean, and easy to work with.

I hope some of the info in the video is useful to some of my fellow aquaponic/hydroponic growers in their quest to find a better, more cost effective growing media.

EDIT:  There is now a second blog entry with some more details about this.... Click on the "Newer Posts" link near the bottom.

Below is the transcript for the video…no need to read it if you’re going to watch the video… I just included it so some of the search engines could pick up on the keywords. ;-)



Hello Everyone. Today I’m going to show a plastic extruder system that I built. The end result was to produce a synthetic, cost effect growing medium for my Aquaponics system.

The extruder consists of a hopper for high density polyethylene pellets. An auger then forces the pellets through a dual zone heating chamber. The heated material is forced through a small die at the end of the chamber.

The temperature in each zone of the heating chamber is controlled by a Teensy AVR microcontroller which is monitored and adjusted through its USB port connected to a laptop.

The auger is driven by a windshield wiper motor and it is geared-down using an old bicycle sprocket and chain.

The hopper is filled with HDPE pellets where they are slowly forced into the heating chamber. It can also be filled with shredded milk bottles or shredded milk bottle caps to add color.

The heating chamber is covered in some fiberglass insulation to conserve heat. There are two thermal probes mounted near the middle and end which provides accurate readings to the controller as the material is heated. The heating elements draw around 16 amps at 12 volts.

The molten plastic that is extruded from the die is squeezed through a set of rollers which embed a texture into the material. A small tube blows air onto the pressed material to cool it, and to keep the rollers cool.

This is one of the rollers after I turned it on my lathe with a close-up view of the texturing.

And this is a close-up video of the material being extruded and pressed through the rollers.

Here is a close-up view of the finished material once it has been cut to length. There is a waffle pattern embedded into the plastic which provides plenty of surface area for bacterial growth. The media lies flat which helps to retain moisture during a drain cycle. The pieces have plenty of spaces between each other for water and root growth.

Most HDPE plastic is classified as food-grade. However, one problem is that nothing likes to stick to it. Even though a texture has been embossed into the plastic, a small amount of movement can disrupt anything that was clinging on it.

This is a time-lapsed video taken with my PlantCam over a 30 day period. There are 3 bean plants growing. I also planted lettuce seed which didn’t germinate, probably because the top inch of the media doesn’t retain moisture like stone or expanded clay.

After 30 days, I removed the beans from the aquaponic system. I had the net basket wrapped in foil to prevent the roots from wandering into the surrounding stone. The roots seem to have an aversion to growing in the plastic and mainly grew between the basket and foil.

Thanks for watching. If you have any questions or comments, please leave them in the comments section below. Also please subscribe to my YouTube channel to see future videos!

Winter season - DONE

In a tragic turn of events, my winter season is over. The circuit breaker for the greenhouse tripped and it went through the night with no heat.

The outside temps went down to 21F (-6.1C) last night while the inside temps went to 27F (-2.8C). Everything got frosted except a few lettuce plants. Tank water is at 38F (3.3C)...goldfish are conserving energy by sitting at the bottom of the tank. They'll be perfectly fine this way until spring.

The end of the normal growing season

Today marks the end of the season for the “sustainable” greenhouse. Last night was the first night the heaters needed to run to keep the plants from freezing. (The heaters are programmed to turn on at 36F). My outdoor growing season ended just shy of 2 months ago so I’m still quite pleased with the extended growing season!

My definition of “sustainable” for this project is not having to add extra heat or lighting for the plants to grow, The other electricity for the pumps and automation is an integrated part of the greenhouse Aquaponics system and I classify that as part of the normal functions. ;-)

I still have peppers, tomatoes, and lettuce growing which should survive for the winter. Of course the cost to keep these plants alive will now skyrocket in electricity costs, but it’s still a nice treat to get a few fresh veggies during the winter.

Already looking forward for spring!

Aquaponic Greenhouse Fall Update

I finally had some time to make another video update of my greenhouse. As you can see, I’m still suffering from a white fly problem and the strawberries just aren’t strong enough to survive. They’re starting to succumb to the flies and are getting mildew on them. I’m probably going to rip them all out, and this winter drop the temp below freezing to kill off the bugs. Bring back DDT! ;-)

There are some stats near the end, so you may want to watch it in full-screen hi-def so you can see the info!

Problem Solved

I was able to build a new wireless bridge. I was given a Linksys WRT54G2 router that "didn't work". These don't have a setting to run in bridged mode, but the firmware can be replaced with the open source firmware from dd-wrt.com. (This firmware has far more features than the one that Cisco provides!)

Next I removed it from its shell and placed it in a surplus NEMA box. The antennas were simply hot-glued on to the circuit board. Working great!

Problems in the greenhouse

Anyone that has watched my greenhouse videos (Click for video) has seen I have it fully automated - I LOVE automation! The best part is I can spend very little time in there dealing with the vents, checking water levels, or even feeding the fish. I can easily disappear for several days and not worry about the system. Well, not really, I always worry about it. I just have to trust it keeps working!

The other day, my web site that collects the data stopped receiving information. I use a Wi-Fi access point (AKA Wi-Fi bridge) that transmits the data to our house - then to the Internet site. Upon closer inspection, the bridge wasn't powered up. I checked the power supply and it was good, then decided to pull apart the bridge. This bridge is designed to be used in the comfort of your home, not the harsh conditions of a greenhouse. It's easy to understand why industrial controllers can get quite expensive. Next time around, I'll probably get the same cheap bridge, then throw it in a NEMA (waterproof) box and try to figure out how to get the antenna through the case....

Winter Update

It's been awhile since I've posted any updates about the greenhouse. We're now in the blistering cold of winter. This is the first year I've heated the greenhouse.....it may be a costly mistake. Here's a little scientific data to ponder:

From Misc

1) 2:30pm: Sun starts to set (yellow) and the greenhouse has no solar gain and the temperature starts to drop (Orange & green lines)

2) 3:45pm: Temperature goes below 40F (4.5C). Heater is able to turn on/off as it maintains the temp at 40F. Ceiling temp (light green) jumps a bit as the heat rises....

3) 9:15pm: Outside temperature (Red) goes below 20F (-6/7C) and the heater no longer can keep up with the demamd. Temperature slowly declines to around 38F (3.3C). The outside temp is 13.3F (-10.4C)

4) 9:15am: Heater turns off once the sun comes out the next morning. Total run time is roughly 17 hours.

There are 2 electric heaters totaling 2400 watts. After all the fees and taxes, we pay $0.20 per kilowatt:
2400watts & 17 hours = 40.8 kilowatts
40.8kW * 20 cents = $8.16 to keep it heated for the night!

Since we are getting so little sun and it's cold, the lettuce is growing very slowly. There's one tomato plant that I started in the fall still doing OK but needs a lot more light. I had a few cukes growing, but the consistent cold has killed them. I am not generating $8 worth of veggies/day. Perhaps it's time to invest in a propane heater to lessen the heating costs....or just shut it down for the winter..... Jan & Feb will be even colder!

Time-Lapse plants

Here's a time-lapsed video of my greenhouse aquaponics transformation. Sorry about the changes in the camera angles and the lighting variations - it's a really crappy webcam. The last frame does have less plants in it since I just ripped out all the beans and started a new batch. I think I may get three growing "seasons" of beans this year.

Strawberry Towers

Here's a couple of pictures of phase 2 of my greenhouse aquaponics system. I'll give credit to Synaptoman for his strawberry tower design....and I've made a few tweaks to the design.

Here's the entire system. I don't have a open pit for the drain, so there are caps on the bottom of each tower with a 3/4" tapped fitting thats drain to the discharge pipe. I was afraid to have each tower hang since this greenhouse isn't really designed to hang that much weight in it. So I took a piece of 3" PVC pipe and made little stands to carry the weight, then strapped each tower to the cross brace to keep them balanced. Each tower has it's own ball valve to regulate the supply water flow.



Last week I chiseled out a few strawberry plants out of the frozen ground and planted them. They're already sending out new growth...early berries this year!!! This setup will hold a total of 48 plants which takes up about 5 square feet.



I had some problems with the water escaping at some of the 'pockets'. The surface tension was just enough where the water would flip off the curve. I took some scrap pipe and cemented a lip to each opening. If this drained into an open pit, it wouldn't have mattered, but I wanted to keep my floor somewhat dry.



This is how the drain from each tower is connected to the discharge pipe. I just cut a bunch of holes in each stand and ran a 1" pipe through it. Also, you can see part of an oval piece on the floor. This goes into the bottom 'pocket' to help prevent the stone from getting stuck in the drain fitting.



After a few weeks, there are now new leaves and they are starting to blossom!



I'm really hoping this setup will work. Strawberries are a lot of work in a regular garden. Plus, just when the berries are ripe, the chipmunks steal them. I'll keep you posted on the progress....