GroBuckets, Sub Irrigated Containers & Off-Grid Subarctic Container Gardening - Frosty Garden

GroBuckets, Sub Irrigated Containers & Off-Grid Subarctic Container Gardening

If you’ve been following along, you know that we extensively use container gardening techniques here in Alaska.

You might have also picked up that we pursue off-grid gardening techniques as this is a reality of Alaskan Frontier gardening.

In 2018, we re-evaluated our entire container gardening approach.  In this process, we settled on the sub irrigated GroBucket system from GroTech Garden Products.

This post details why we made the change to sub irrigated systems and the benefits that we’ve seen from this system.

Why Do We Use Container Gardens In Alaska?

Container planting has always been part of our gardening strategy in Alaska.

In our cold climate and cold soils, container gardening is a highly beneficial way to improve the results of virtually all warm weather crops.

In 2016, our first year of subarctic gardening, we did a side-by-side trial of every variety of pepper and tomato we grew outdoors, in both containers and raised beds.

It wasn’t even a contest.  The container gardens won, by far.

The soil in Alaska is just too cold, even in a raised bed, for warm weather plants like tomatoes and peppers to thrive. Putting these plants into containers allows the soil to warm more quickly and we get much improved results.

This picture shows some of our fabric grow bag containers that we primarily used for growing warm climate crops in the subarctic.

With this testing, we decided to integrate container gardening into one of the core gardening techniques that we use in our subarctic gardens.

For a few years, we raised some of our plants in our fabric grow bags and they worked great for us.

Why Did We Need To Make A Change?

One of the biggest disadvantages of traditional container planting is inefficient use of water, especially when using fabric based grow bags.

Not only do you experience evaporation and overspray when you’re watering, a lot of water is wasted by draining right through the container.

As we expanded our gardens on our off-grid homestead, we began to struggle with water utilization.

It’s probably important to further explain that our home’s subarctic water system is entirely off grid.  We have a water tank that feeds our home, which has to be filled on a regular basis.  While this is a fairly common thing in the Alaskan Frontier, it might come as strange to some of our readers.

Our home water is extremely expensive since it is trucked to our home on a bi-weekly basis.  It’s also incredibly finite.  We try to avoid using our home water for our gardens as it significantly raises the cost of gardening for us.

We did some research and analysis on our water losses using traditional container gardening methods.  Basically, we discovered we were experiencing extremely significant water losses.  The kinds of losses that would add up to thousands of dollars over the years.

When we bought our home in the Alaskan Frontier, our first priority was to invest into a capable rain water catchment system.  We knew that any garden will place a significant demand on your water systems.

The problem is, we can’t just make it rain whenever we need water.

So, with our research, we were incentivized to make a change towards a more water efficient gardening solution.  Queue the research!

Choosing The Right Subarctic Container Garden

Fabric grow bags weren’t going to cut it on an off grid system.

We did some research on what some of the options were. As we did our research, we came up with a few options:

  • Drip irrigation techniques
  • Hydroponic systems
  • Sub irrigated growing systems

These are all fairly well known to achieve more optimal water utilization.  All of them could be adapted to our environment and gardening situation.

Unrelated to our current problem, I had previously come across a Kickstarter for a product called the GroBucket, from a new startup company called Low Tech Engineering, LLC.

It was basically a kit that could easily turn a standard 5 gallon bucket into a sub irrigated container.  As we looked into them again, I noticed that the product was now available on Amazon

Cool, a successful Kickstarter product.

The more research we did into this solution, the more we liked it.  They had really thought it through.

  • Easily made from commonly available products (5 gallon buckets)
  • Very simple to put together
  • Easily stored (stackable) for winter storage
  • Very scalable, based on how many we wanted to buy

This is our entire GroBucket system, stored for the winter.  (Except for the buckets)  As you can see, it takes up very little space due to the fact they were designed to be stacked.

The product was somewhat expensive, but not totally out of line pricing wise.  When we compared it to other gardening solutions, it was right around the same price.

As I considered the other options, the GroBucket became the obvious choice for an initial trial.

What Is A Sub Irrigated Planter, Anyway?

If you’ve ever “bottom watered” a plant, you have essentially practiced sub irrigation. 

Sub irrigation has been around for a long time, the Hanging Gardens of Babylon were based on the concept.

The underlying concept behind sub irrigated systems is pretty simple.

You basically have a reservoir of water that is in constant contact with the container’s soil, typically at the bottom of a container. Soil will naturally wick water from that reservoir, keeping an even moisture level throughout the soil in the container.  As water is absorbed by the plant, the reservoir of water will continually replenish the soil’s moisture.

The “trick” with sub irrigation is that it will feature an “air gap” between the level of the water and the soil.  That gap ensures that the plant does not drown in the water.

Sub irrigated systems are sort of a blend between traditional soil gardening and hydroponics. Instead of inert media used in hydroponics, you’re using soil instead. Instead of purely liquid nutrients in hydroponics, you might rely on compost or traditional fertilizers.

You can also treat a sub irrigated system similar to how you would a hydroponic system.  This allows you to utilize water soluble fertilizers, which allows you to worry less about the nutritional health of the container’s soil.

What About DIY Sub Irrigated Containers?

We generally like to pursue DIY solutions here at Frosty Garden.  When they make sense.  In our particular case, it didn’t make as much sense.

There have been DIY versions of sub irrigated planters out there for ages. Commonly based on 5 gallon buckets, many people have put together DIY versions of sub irrigated planters using various methods.

We put together a bill of materials for these systems to figure out how much they would cost.  Every DIY solution we looked at penciled out to $10+ per grow site for us, requiring two buckets, plus several other parts.

It would also take many hours of preparing the 30 or so buckets we wanted to start with.

For a few dollars more, a commercial solution saved dozens of hours of work.  It also halved the number of buckets we needed.  Acquiring so many buckets in a small town like Fairbanks, Alaska is likely to present some troubles.

Given the other benefits of GroBuckets, such as rapid deployment, ease of setup and being designed with the idea of storability in mind, the commercial solution started to make a lot of sense.

Sometimes commercial solutions are the better option and that was apparent in this case.

What About Alaska Grow Buckets?

Ah, you’ve been paying attention to sub irrigation 101!

The Alaska Grow Buckets are a similar sub irrigated system, designed by Jim Lister of Wasilla, Alaska. All ready a hometown favorite.

These were seriously under evaluation and may still have have a future home at Frosty Garden’s homestead. Or, perhaps a hybrid approach with GroBucket sub irrigation hardware.

The real problem for us with the design was sourcing sufficient quantities of appropriate colanders that could be used. We weren’t able to locate super cheap colanders here in Fairbanks and Amazon wants $8-$10 for almost any colander they sell.

There’s also the matter of sourcing shopping bags, again for 30+ buckets. A few dollars here and a few dollars there and you might be spending more time and money than a commercial solution.

With DIY, sometimes there are issues of repeatability and practicality.  It’s great to be able to “one-off” something with used materials and it’s awesome when you can get it to work.  But, when you’re trying to make 30+ of something, you often will need to source the materials unless for some reason you have them all on hand.

What we do really like about the Alaska Grow Buckets is the solution for root air pruning. The holes in the side of the bucket are genius, taking a sub irrigated bucket into the same realm of fabric grow bags. It literally could be the best solution out there and the concept is also easily integrated with the GroBucket hardware.

We hope to eventually do a little bit of a trial with one or two of our GroBuckets featuring the Alaska Grow Bucket holes for comparison sake. I suspect this may provide for great plant improvement with only marginal increase to water evaporation.

Why Not Go With Hydroponics?

I’ll admit that I was a little bit excited at the prospect of getting back into a hydroponic system again.

I primarily considered the Dutch Bucket system of hydroponics.  This is a recirculating/drip system that does really well with larger plants such as tomatoes, peppers and many other larger plants.

Several factors worked against the decision to go hydroponics, though.

  • Hydroponics systems are not very mobile, defeating one of the main advantages of container gardening
  • Moving the system requires almost an entire re-design of the system
  • They aren’t as flexible for other plants we might choose to grow, such as root vegetables and others.
  • They penciled out more expensively than the GroBucket system, by a fair bit
  • Hydroponics is an entirely different growing system, requiring separate fertilizers and other products to maintain healthy growth

While it was interesting to consider, it was going to be easier to just go with the GroBucket system.  It’s a good backup plan if they didn’t work, though.

Our Initial Trial Of 30 GroBucket Sites

Ultimately, we settled on trying out the GroBucket solution.

Initially, we put in for 30 GroBucket units and would assess our future purchases based on the initial trial.  We also continued to use our fabric grow bags, side by side.

We wanted to see what we could do with the GroBuckets, so we planned several types of plants to grow in them.  Our initial trial comprised of:

  • Tomatoes
  • Peppers
  • Eggplants
  • Ground Cherries
  • Brassica (Brocolli & Cauliflower)
  • Potatoes (Root veggie!)

Needless to say, it didn’t take long until we were completely sold on the product.

Everything we grew in the GroBuckets was far and away better.  Our harvests were larger, our plants were healthier and we had very few problems with the system.

It was also immediately apparent how much more work we had to put into our fabric grow bags.  For every one GroBucket watering, we had to do three or four waterings of the fabric grow bags.

As for water utilization, we got exactly what we wanted.  Our water usage went way down and for the first time, we didn’t have to use our expensive home water on our garden.

Even our root vegetable test with potatoes worked out!  We were able to harvest around a dozen potatoes, which is about average for a 5 gallon bucket.  They tasted fine and were super easy to harvest.

Expanding The GroBucket Growing System

We quickly became “fans” of the GroBucket system.

The following year, we decided to replace all of our container growing with GroBuckets.  This brought our total GroBucket system up to around 70 containers.

Again, we had a great year.  We loved how easily we could expand the system.  We could just decide to spend the money and increase the container garden’s size.

As we got above 50 buckets, though, another problem started to emerge.  It became a bit cumbersome to water all those buckets.  It wasn’t as easy as the (totally wasteful) watering with a hose sprayer like we used with fabric Grow Bags.

We began to research how we could centrally irrigate the system.  The GroBucket system lends itself rather well to central irrigation, mostly because it requires you to level the water between the vessels.

Centrally Irrigating Your Off Grid GroBucket Garden

We have an in depth article on this subject, but we decided to centrally irrigate our GroBuckets.

Conceptually, what we wanted to achieve was a way to fill a singular reservoir and have this replenish the water levels in the individual buckets.  We wanted to go weeks in between watering, if possible.

In 2020, we planned on building our greenhouse.  We decided that we wanted to use the GroBucket garden as the basis for this greenhouse.  To make things easier, we also wanted it to be centrally irrigated from day one.

At this same time, we also centrally irrigated our deck container garden that used the GroBuckets as well.

Both systems are designed very similarly to one another.  Both rely on a central reservoir, interconnected to the buckets with standard irrigation tubing.

We really liked using irrigation tubing as the basis for the irrigation system.  It is inexpensive, easy to acquire parts for and allows a lot of flexibility.

The “trick” with this central irrigation is to have all your GroBuckets at the same level.  It also involves what is called a control bucket, which is used to determine the water’s level.

This irrigation technique borrows from a physics principle that water will always seek its own level.  If you can limit the water’s height (with a float valve in our case), you can ensure all the buckets have the same water level.

We do sill operate a few of the buckets outside of this central irrigation systems.  For example, we have our herb garden entirely separate.  This allows us flexibility to treat the GroBuckets how we want to treat them.

Exploring Fertilization Techniques With GroBuckets

We have done some experimentation with fertilization and our GroBuckets over the several years that we have operated them.

In our container gardens, we have to be a bit concerned about our container soil’s fertility.  We re-use our soil from year to year, meaning it often is depleted in nutrients at the end of the year.  This means we have to put some focus on revitalizing our soil for use the following year.

The GroBuckets can be fertilized using traditional techniques (top fertilization), infusion of fertilizer with the soil and even techniques that look more like hydroponics systems.

We tried all of the above experiments to find out what we liked.  We have settled on treating them similarly to hydroponics systems.  This technique is also called fertigation.  We use our standard non-organic and liquid soluble fertilizer, the JR Peters brand of fertilizer.

The JR Peters fertilizer features a “constant feed rate” which basically is the amount of fertilizer you would use if you fertilize with every watering.  Essentially, this is about one quarter of the normal fertilization rate.

Instead of intermittently feeding our GroBuckets, we always feed them.  In our centrally irrigated setup, we simply add the appropriate rates of fertilized water and we never have to worry about whether our plants have sufficient fertilizer.

This technique has performed absolutely tremendously for us and has sent our food production through the roof.  We have been able to achieve significant improvements in growth, maturity rates and plant health.

With this technique, you only have to worry about plants that don’t handle heavier fertilization rates very well.  Fortunately, these are few and far between.  If you are growing these kinds of plants, it’s best to keep them separate so you can treat them differently.

Is the GroBucket System Right For You?

If you are looking for an excellent off-grid container growing system, the GroBuckets are well worth your time to further research.

We know they aren’t super cheap and DIY, but we absolutely love ours.  The central irrigation systems we built have transformed our garden into a vision we’ve had since we started gardening.

Hands off.  Fully automated.

Our systems have held up through multiple years and we have few concerns about the long term use of them.  Our system is getting to the point where we need “spare” equipment and such, so we have pursued that.

The people behind GroBucket are also great.  We’ve been in contact with the company several times and they are great to work with.  They even tracked us down to get in touch, which was really sweet of them!

8 comments… add one
  • Shawn Cleary Jul 7, 2019 @ 12:11

    I have 10 GroBuckets, 9 Tomatoes and 1 for peppers (2 plants). It’s my first go-round with them, and so far, so good. I am toying with the idea of filling the reservoir, once a week, with my organic fertilizer, as my fruits have started. I am also finding that I am filling them at least 2 times every 3 days, but we have had a stretch of 90 degree days.

    • Jeff Jul 7, 2019 @ 12:31

      Cool, we really like ours as well! We find that filling ranges from every 2 days (squash) to almost a week plus (peppers/tomatoes). We don’t usually get that hot here. We have also started using liquid soluble fertilizer in the buckets for high demand plants, such as squash and tomatoes. The most challenging for us has been squash, because they drink so much, but I’ve never seen better growth from squash either! We will likely consider more of them, we like them so much!

  • Mike Chavez May 10, 2020 @ 4:04

    Any idea how many seasons the GroBucket will last before it needs to be replaced?

    • Jeff May 10, 2020 @ 10:42

      The product is made from a reasonably high grade plastic. I’d suspect at least 10 years if you take good care of them, but there’s no reason they couldn’t last much longer. We haven’t seen any reliability issues thus far.

  • Camille May 9, 2022 @ 23:55

    Hi Jeff,

    Really like your article a lot!

    Can you share with me what soil/soiless mix you use for the hydroponic fertilizer solution? Do you start with soiless grow medium and apply liquid fertilizer from the start?


    • Jeff May 10, 2022 @ 19:08

      Hi Camille. Thanks for your kind comment. We decided to go soil in ours and I still think that’s best for the moisture wicking capabilities that this system needs. We actually make our own soil, it ends up a fair bit cheaper at our scale. (100+ buckets & containers.) We detail our soil processes fully here, we use the “Frosty Garden Secret Weapon” recipe about a third of the way down the page. Most store bought soils would also work and this is definitely cheaper for smaller systems and gardening efforts. If I was going that route, I’d probably use Promix in them. For fertilizer, we use Jack’s (aka JR Peters) line up. We like this lineup because they provide a “constant feed” rate, which is helpful when you start to blur the lines between soil and hydroponics like we are with this system. Hope that helps!

  • Chelsea Nov 8, 2022 @ 3:06

    Great post! How deep do you plant your tomatoes in the grobucket system? I have 10 of these and not too sure how deep to plant my determinate tomatoes.

    • Jeff Nov 10, 2022 @ 9:33

      We typically will plant our tomatoes as deep into the bucket as is possible that still allows some greenery to be above the soil. The specific depths depend on when we start the tomatoes and how big they are at the time of transplant. Tomatoes will grow roots on stems that are submerged under the soil, no different in this system! We do one plant per bucket. No matter what you do, the plant will grow!

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