The Tomato Plant Container Size Experiment Part 1

So, around about October I begin to plant tomatoes out into their containers for the season. I usually plant the majority in the ground, but like to have container plants as well, as they often ripen quicker.

But then I am faced with the question, what size container should I use, and what happens if I use a smaller container?!

This year we find out.

Introducing the Tomato Plant Container Size Experiment

Last year I looked at what effect growing a range of different plants in different potting mediums would have on their overall growth and yield. The answer was surprising. There seemed to be little to no difference regardless of whether I used a special potting blend, Al "Tapla's" well-known 5-1-1 mix or straight off the shelf $2.50 potting mix. This flew in the face of everything I had read about soil properties and improved growth, and although by no means a conclusive experiment, it definitely was interesting to see such little difference.

This year I am going to look at how container size affects growth of tomato plants. The experiment will be simpler than last year, and will simply look at what happens to tomatoes as you decrease the container size.

Overview

I will be using three different container sizes for this experiment, and will have two tomato plants per container size, so we can see if there is wild differences in growth or yield even between plants in the same container size.

The containers I will be using are below, and from left to right are 13 liters, 23 liters and 42 liters.

By the time I has used all my soil medium, the containers were not quite full, and so I will estimate that the actual soil volume in each is somewhere between 9-11 liters, 18-21 liters and 36-39 liters respectively. 

From left to right 13L container, 23L container and 42L container (as marked on containers)

I chose a variety of tomatoes from the local hardware store, that were approximately uniform size and health. The punnet came with 8 plants, this experiment will look at 6 of those plants.

The tomatoes used in this experiment

More information, for those interested

I will simultaneously be growing other tomato plants in the ground, and in other containers which I may refer to, but these wont be used as a comparison for this experiment.

What sized container is actually recommended?

It is difficult to find a straight answer when searching for what size container to use to plant your tomatoes in, with some ranges between 10L as a minimum and up to 60L or more as being recommended. 

This site suggests 30L as a minimum stating;

I find the most important factor is volume of dirt. I use containers that hold 30 liters (7.3 US Gallons), and I find this is both the minimum but also an amount that usually works okay. More is obviously better, if possible.

This thread from GardenWeb seems to come to the consensus that 5 Gallon containers (18.9L) are sufficient, even for growing beefsteak tomatoes.

And this page from the North Carolina State University says that the range of container size is anywhere from 5 - 20 Gals (18.9L - 75L).

Why should we even care - just use a huge container!

Anybody that has planted a number of container fruits or vegetables knows that as container size increases, cost seems to exponentially go up. And the more you plant, the more you cop it.

With increased container size you need not only a more expensive container, but also more quality soil mix to fill it. As size increases so does the weight of the container, and a 60L container with soil and a plant (weighing up to 45kg itself) can be a nightmare to move around!

So the goal should be to find the very minimum container size that provides sufficient quality and quantity of yield to be worth the effort of growing. 

The soil mix used in this experiment

Despite finding in my last experiment that ordinary old potting mix performs just as well, old habits die hard.

The mix I used for this experiment is the same for all container sizes.

I started by rehyrdrating a block of coconut husk chips. I used the blocks sold at Bunnings, which go for about $12-13 and are far inferior to the chips I have used previously. They are much larger, and just seem less refined. I prefer the orchidmate brand, which can be found online.

The packet of the husk chips says that it expands to up 60L, but here it is after being wet, in a 62L container. I estimate it expands to a volume of about 30L or less.

Re-hydrated coconut husk chips

I split the husks in two even parts, and to each part added the following:

1 bag of orchid mix, which appears to be composted bark, of about 5-10mm grade.

Can be found at Masters hadware stores for about $8 per bag

1 bag el-cheapo potting mix

This is a $5 bag. Couldn't find a $2.50 bag anywhere!

2 large handfuls of organic tomato fertiliser, and 2 large handfuls of fig fertiliser, which is made up of super-phosphate, bonemeal and dolomitic lime.

Add fertiliser

Organic tomato fertiliser

Mix all together and we have our mix. It is a nice damp, loose and aerated mix that should allow for good root growth! Here is a quick vid, please excuse my shaky and unfocused camera-work!

Filled, transplanted and ready to go

After filling all my containers with my soil mix, I have transplanted my tomatoes and am ready to watch and record them grow! As the nights are still quite cool here in Canberra I will be lugging them in and out of the garage each night to protect them from any frosts.

All lined up nice and pretty!

So stay tuned. I feel I am lacking a really big container comparison, the 60L group, and I do have 2 more plants left over... so I might end up adding another two plants tomorrow !

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Some garden updates

Garlic

Way back in December I harvested my garlic. An afternoon of digging and tying yielded a good number of bulbs, and after giving some away and using a bunch, I still have a whole lot available today which I use almost every night.

Garlic after harvest

The garlic is sharp and flavourful and exceeds the garlic bought at the shops or markets by a long margin. I divided the garlic into bunches and store in my shed, hanging a bunch in the cupboard until ready for use.

About half of my garlic, bunched and ready to go

Close up of a fresh bulb

Four months later, the bulbs store nicely, ready to be cooked!

Vegetables

After planting up my veggies in Oct/Nov after out frosts, I have unfortunately let things lapse in the commotion around the twins birth. Regardless of this, I still manage to haul a good number of vegetables every week.

Here is today's haul, capsicums, tomatoes, beetroot, chillies, tomato, squash and eggplant.

Todays haul

Tomatoes

My tomato vines were ravaged by the heat this year. Tomatoes literally cooked themselves on the vines, and my inattention caused the vines to sag and drop.

Luckily for me the plants still produced nicely. Two weeks ago we pulled this massive lot from the garden.

Periform Abruzzi

Golden Grape

Tommy Toes

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October- A month of Highs and Lows and The Great Container Mix Experiment Begins

Extreme Weather

Well, Canberra has had quite interesting weather in the first couple of months of Spring. Unusually warm days followed by unusually cold nights means that I have been hauling my seedlings back and forth each morning and night into the shelter of their grow closet. It’s getting quite tedious. Being several months old now all the seedlings are getting larger, and the tomatoes especially have begun to outgrow their nightly home.

Seedlings Get Brought Under Lights on Frosty Nights

Chillis, Tomatoes and Okra

Tomatoes Outgrowing Their Pots

Officially, Canberra has experienced an average low temperature of 3.8 degrees Celsius which is 2.2 degrees colder than the average for October. Maximum temperatures have been 2.3 degrees above average for this time of year, averaging 21.8 .

On the 18^th Canberra also experienced its coldest October morning on record, dropping down to -3.4, beating the record of -3.3 set in 1957. This frost severely knocked around many of my plants, especially the potatoes, grapes, mulberry and one of my figs that was planted in ground. Many of these plants were half defoliated, and the fig lost all its leaves. Luckily for me, the majority of my figs are in pots up off the ground and all except the black genoa went unharmed. Black Genoa does seem a little more frost tender than my other figs, and has lost leaves twice due to frost since breaking bud in September.

Fig Tree Totally Defoliated in Record Breaking October Cold

Frost Damaged Potato Plants

Despite the continued looming threat of frost, on Sunday I took a gamble and planted out many of my tomatoes, capsicums, eggplant, chillies and zucchini. We still have a 0 degree day predicted for Wednesday morning, and I am hoping it will be our last for the year.

Continued Risk Of Frost

 The Great Container Mix Experiment Finally Begins

I also chose Sunday as the day to plant out my seedlings for the Great Container Mix Experiment.

Looking at all the seedlings  I had available to me, I ended up choosing Okra, Fatalii Chillis and Banana Chillis as three of the four varieties to be tested.

Okra, Fatalii Chilli and Banana Chilli

Banana Chilli, Fatalii and Okra

All the plants I chose were fairly uniform in current growth and height, except for one banana chilli, which was significantly smaller than the other two. I decided to pot this chilli into my coconut husk mix and will see if it can catch up to his bigger brothers over the next few weeks.

Below are the starting sizes of each of the plants potted into the various mixes. I will use these sizes as an initial benchmark to compare to over the coming weeks. All plants are equally sized except the small banana chilli.

Crimson Okra in Coconut Husk Chip Mix

Crimson Okra in Commercial Potting Mix

Crimson Okra in 'Fine' 5-1-1

Fatalii in Coconut Husk Chip Mix

Fatalii in Commercial Potting Mix

Fatalii in 'Coarse' 5-1-1

'The Runt' Banana Chilli in Coconut Husk Mix

Banana Chilli in Commercial Potting Mix

Banana Chilli in 'Coarse' 5-1-1

I still have three pots left over, and am not sure what I will plant in there as yet. I am thinking to direct sow some Edamame (soybean) seed. I initially was planning to put some grape tomatoes in there, however I have since decided the pots are too small.

I will shuttle these pots back and forth into a small plastic greenhouse I have on the colder mornings.

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Raising Seedlings Under Grow Lights and Garlic Update

Garlic Update

The garlic grew all throughout the Canberra winter, and it appears that the hardneck types enjoy the climate more so than the softnecks. The hardneck types are quite large and robust, and the softnecks are wimpy in comparison. The plants have not yet sent up their scape, and are a few months away from harvest. 

It looks like I will have a good number of bulbs in a few months, hopefully enough to last many months!

Growing Nicely

Hardneck vs Softneck Garlic

Raising Seedlings in Canberra's Winter

This year I am growing a number of warm season crops, that require extended periods of warmth to produce, in particular super hot chillis and okra. In order to get the best out of the season I have decided to start these seeds early in an electric propagator under grow lights. I started many of my seedlings in early August, and am continually producing more, as space allows.

To make this process as easy as possible I retrofitted an old cupboard into a seedlings nursery.

An old wardrobe I picked up for $40 and converted into a plant nursery

The Wardrobe When Closed

The wardrobe is particularly useful in our cold winters as it stays between 20-20o C when the ambient temperature is cold, and on a warm day such as today (24o C) the hottest chamber sits at about 30-35o C with the door cracked open. 

I found out the hard way that keeping the door totally closed on a warm day can send temperatures in one of the compartments up to 40o C, and I cooked one or two seedlings in a fiery inferno of death.

Lets take a closer look inside.

Left Hand Chambers

The left hand side has a 250W high pressure sodium lamp with a reflector attached to spread the light.  

The bulb is enclosed in a cool tube, which is ducted to allow cool air to be drawn over the bulb and straight out of the wardrobe, on the right hand side, preventing over heating. This currently works very well, and if anything, the left hand compartment is slightly cool, and I rest some plants on a cardboard box to put them closer to the light for additional heat. I suspect that I could add a 400W bulb without too many heat issues, although as the ambient temperature heats up cooling will become more important. A fan attached to the left hand side of the cool tube is orientated to push air over the cool tube, rather than suck air through.

The fan is powerful enough to suck air from holes drilled in the right hand wall, cooling the right hand chambers as well as the left. The left hand door of the cupboard will drift open if allowed to do its own thing, however the suction is strong enough to keep the door closed as long as the fan is running. On several occasions I have come to find the door has drifted open after the fan goes off, and when it resumes there is no cooling effect in the right hand chambers, and in these cases the temperature has raised to 40o C quite quickly.

This compartment is large enough to hold two medium sized tomato or chilli plants, or one large wide plant. There is approximately 150cm of growing height.

Left Hand Chamber with 250W HPS and Fan Venting Air

Right Hand Chambers

The right hand chambers are split into three compartments; a storage place for the ballast for the HPS as well as all the power boards to operate the heated propagators and compact fluorescent lights, and two growing areas for seedlings and young plants.

The growing areas each have two compact fluorescent growing lights each at 130W, some in a blue-white spectrum, and some in more of a red spectrum. These CFLs produce about 8000 lumens each. These are very bright and leave you with stars in your eyes after looking for too long!

Two Seedling Raising Compartments

Red CFL vs Blue/White CFL

Lights on the Bottom Compartment

In the germinating compartments I have all the seedlings initially started in seed trays on electric heated propagators. I leave the covers on until the first seedling emerges and then remove it. The young seedlings in the above picture are fatalii chillis. 

The top compartment has okra, capsicum, eggplant and tomato seedlings and usually stays at around 30-35oC, the bottom compartment stays slightly cooler at around 25oC (door had been open a while at the time I took this picture so temperature reads a little cooler).

Various Seedlings in a New Larger home 

You can also see throughout the wardrobe I have used reflective silver sheeting and silver tape to maximise the light output from the globes. The sheeting comes on a large roll and is dimpled to prevent the formation of local areas of heat, known as hotspots which can cause heat damage to plants. I attached the reflective sheeting with a combination of glue and reflective tape. 

Light Timers

The lights within the wardrobe are on timers, which leaves the lights on for approximately 18 hours a day, and dark for 6 hours. I have the heated propagators on a seperate timer, with the mats going on for about 2.5 hours and then off for about 1.5 hours. This is because one heating mat was getting too hot and cooking seeds with 24 hour operation.

Timers and Exhaust Ducting

Potting Up Seedlings

I potted up a tray of my seedlings today as I felt they were large enough to be re-homed from the seed-trays they were germinated in. I potted them up in small pots from bunnings, 50c per pot.

When transplanting seedlings it is important to be extremely careful, and to try your best not to disturb the roots if at all possible. These seedlings had not seen natural sunlight before, and had not been hardened off in any way, and in such situations it is important not to leave them sitting in the full sun and wind for hours, as it may do damage to the tender plants.

Before Potting Up

After Potting Up

When potting up or transplanting seedlings it is important to consider the growth habit of each plant as this can affect the way you transplant. For instance the okra in the above photo have a tap root which if damaged will significantly stunt the growth or even kill the plant. Tomatoes on the other hand are much more resilient, and will even sprout new roots from the stem (still be careful though!). 

Tomatoes can actually be planted to just below the depth of the first leaves and this will strengthen the plant as it will develop a more comprehensive root system, sprouting roots all along its stem. Other plants will damp off and rot away if you plant the seedling below the depth where it originally grew. 

The plants above have been placed in a mixture of seed raising mix, bagged compost, perlite and diatomaceous earth. I also water them with a dilute solution of water and seaweed to help with transplant shock.

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Holy Cucumbers Batman!

Well Friday is traditionally the day I scout around seeing what is ripe in the garden for picking. Today I had a few of veggies available.

My zucchini has finally started to slow down after 2 months of huge, and I mean HUGE, fruit. Honestly zucchini is one vegetable I am adapting my approach to next year. The plant itself grows large, and the huge leaves smother anything planted close. The fruit themselves grow exceptionally fast, and produce huge (but tasty) up to 1kg each. Next year I will give the plant plenty of space, and 1 bush is definitely enough. 

Tomatoes this year have not been spectacular. I planted them late, towards the end of December, and it has only been in the last 2 weeks that fruit have begun to ripen. Long dry spells punctuated by heavy rain caused many of the fruit to crack, however they are still sweet and full of flavour. I tried a new growing technique this year, growing tomatoes up strings and removing all the excess suckers. I found these bushes much easier to manage and hope to test the system out again next year. Hopefully with more favourable weather.

The Lebanese eggplant in this picture are the first I have harvested. The plants themselves are strong growing, and I wish I had planted them sooner, as I think they would have cropped well. I have another 2-3 almost ripe fruits on the plants which will come off in the next few days, ready for some eggplant inspired dish.

The Cayenne chillies in this picture have become a normal occurance, ripening 6-7 chillies every few days. There are still absolutely tonnes of green chillies on the plant, and this weekend I am going to try and convert it to a hydroponic system so I can keep it producing throughout the winter. In Canberra there is a slight frost risk coming up on Monday, and this is going to get progressively worse.  

But the cropping plant of the year award goes to...

Cucumber

Before this year I had never grown cucumber. It's not something we eat particularly much of, and years ago we received a free packet of seeds, which I decided to plant. Out of the six seeds I planted, all of them germinated. Of them, five remain today, one suffering a freak and horrific dog-trampling accident.

Cucumbers were planted from their seedling trays in January, and for the last four weeks I have been taking HUGE amounts of cucumbers each week. Every Friday I go out and see what has ripened, and this week I had a record 27 ripe cucumbers.

Of everything in the garden this year, giving away cucumbers has been the hardest!

For future reference, if this year is anything to go by, 1 cucumber plant is ample. AMPLE! The picture below is just todays harvest, and I have had similar over the last 3-4 weeks!

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