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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Sweet Corny Goodness

Sweet Corn

Home-grown sweet corn is a must for the garden, if you have the space (and enjoy corn!). For maximum sweetness and flavour, sweet corn must be consumed as soon as absolutely possible from the time of picking. This is because the sugars within the corn kernels begin to transform into starches, which reduces the cobs sweetness. This means, that the corn you buy from the shop will never be as sweet and tasty as the corn you grow yourself!

Today I harvested my first four sweet corn cobs, and I have another 6-7 almost ready to be picked on my plants.

Growing Sweet Corn

Sweet corn is a fairly easy vegetable to grow. It is a hungry crop in that it takes a fair bit of nutrients from the soil during its growing process, especially nitrogen. Because of this, it is not a good idea to plant corn in the same area as a previous corn or other nitrogen hungry crops. Instead, try planting in a bed that has had legumes such as peas or beans growing, as these plants fix nitrogen into the soil through symbiotic relationships with soil bacteria.

Fresh packet corn seed germinates very readily. The seeds should be planted directly into the bed where the plants are to go. For corn, it is best to plant in blocks, as the plants need to be pollinated by wind, and close contact will help this. Plant each seed a minimum distance of 30cm apart. In warm soil, you can expect germination within about 10 days. 

Corn is a warm season crop, and will start to die when average temperatures drop below about 16oC. In Canberra this occurs by about the end of April and into May. If, possible corn prefers a warmer temperature than this, around 25oC. 

From sowing to harvest, sweet corn will need between 10-12 weeks before cobs are ready to harvest. The plants from the photo above were planted in the first week of January, and were harvested on the first of April. In Canberra, January plantings of corn may fail if early Autumn temperatures arrive, and would preferably be planted earlier, after the last frost in November or December. To prolong the corn harvest period, plantings should be staggered.

Fertilising Sweet Corn

Each sweet corn  plant produces both male and female flowers. Male flowers are produced on the top of the corn stalk. They can also be identified by finger-like straight flower. Male flowers produce copious amounts of pollen, which is blown by wind onto the female flowers;

Male sweet corn flower

Female flowers look like strands of fine golden silk, and are generally located toward the middle or bottom of the plant. Corn plants will generally produce between 1 and 3 female flowers per plant, and each of these female flowers can develop into a corn cob. If all the strands are fertilised successfully then all the kernels in the cob should develop, and corn cobs with missing kernels mean that not all the silk strands were pollinated successfully.

To aid with pollination it can help to give each of the corn stalks a shake whilst the female flowers are still young and still golden. If you wait until the strands have turned brown then it is too late. Typically this lasts for about 2-3 weeks.

Female sweet corn flower with new, golden strands and old, brown strands. This cob will be ready for harvest soon.

Harvesting

Sweet corn needs to be picked as soon as it is ready to ensure maximum sweetness. This can be recognised in two main ways. Firstly the silk tassels on the female flower will all die down into a brown colour and no, or very little golden strands will remain. The second test you can do involves peeling back a small piece of the husk until the kernels are visible, and then pierce one with your fingernail. If the liquid that comes from the kernel is clear, the corn is not quite ripe, but if it is cloudy then the corn is ready to pick. 

When picking the corn, grab the cob and pull downwards twisting at the same time and the cob should come right off easily, without damaging the plant.

Ripe, un-husked sweet corn cobs, and ripe husked cobs.

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Growing Blueberries!

Along with figs, this year I am trying my hand at blueberries. I currently have seven varieties, six in containers.

Blueberries 

Blueberries can be a little trickier than some fruits to grow. They have specific soil and nutrition needs and for decent crops need to be cross pollinated. Blueberries are often advertised as self-fertile, however cross pollination with another blueberry of the same type will greatly increase both yield and berry size. Blueberries also require a number of chill hours in order to set fruit.

However it is important that you choose blueberry plants from the same type, as not all blueberry plants will cross-pollinate with each other.

Soil selection

Blueberries are quite particular in their soil needs. They enjoy an acidic soil with a pH between 4.5-6.

Blueberries over time have adapted to lower pH environments, which today means that they will suffer mineral deficiencies in higher pH soils. In particular blueberries will suffer from an iron deficiency as their ability to absorb iron decreases with higher pH. Iron deficiency in blueberries is marked by chloriotic (yellowing), leaves.

Blueberries also require a free draining soil, free from weed competition. Blueberry root systems are very shallow.

Nutritional Needs

Blueberries have a different root system to the majority of plants. Normally, plants will form roots, and then fine feeder hairs, to collect nutrients. Blueberries lack these fine hair-like roots, and instead, form a symbiotic relationship with mycorrhizal fungi.

Blueberries are somewhat different from other plants in their nitrogen needs. Nitrogen (N) is an essential element that promotes leafy growth in plants, and in most fertilisers exists in a nitrate form. In chemistry nitrates have a chemical composition of NO3. Blueberries, and some other acid loving plants, prefer to receive nitrogen in an ammonia form, which has a chemical composition of NH4. Because of this, it is important when choosing a fertiliser for blueberries that you select one with an ammonia based nitrogen source. Generally, this can be found in acid-loving fertiliser mixes.

Below is a picture on the difference in blueberry root development when fed with a nitrate (NO3) vs ammonia (NH4) based fertiliser. The source of this picture, and lots of additional fertilising information can be found in this paper.

Blueberry Types

Blueberries come in three common types, blueberries will cross-pollinate with other plants within the same type, although some studies have shown limited cross pollination with blueberries of another type, in particular Southern Highbush and Rabbiteye types. To be safe, plant at least two varieties of the same type together.

Highbush

Highbush blueberries are so named because of their taller stature, sometimes growing up to 3m tall. Highbush types have a high chilling hour requirement, needing at least 1000 hours under 2oC to satisfy their dormancy requirements. These plants are quite hardy and frost tolerant. Highbush types are also able to tolerate high summer temperatures, making them great for cooler Australian climates.

This year, I have planted two varieties of Highbush blueberries

Blue Rose

Denise

Edit, on 30 March I added two new Highbush blueberries to the collection; Brigitta an Blue Crop

Southern Highbush

Southern Highbush types have lower chill hour requirements than Highbush types, needing between 250-600 hours of chill. Southern Highbush types do not have the frost tolerance of Highbush types and must be protected in areas like Canberra. Southern Highbush types have a tolerance for heat.

In Australia Southern Highbush varieties account for up to 80% of total blueberry production, due to the extended growing season.

Growing Southern Highbush types in Canberra can be troublesome due to our cold winters. Blueberries are perennials, meaning they live for many years, and in cold areas will die back each spring as cold weather approaches, to re-grow in Spring. Blueberries in containers should be moved to a warmer location to over-winter, and Southern Blueberries in the ground need extra frost protection if they are to survive.

This year, I have three Southern Highbush varieties

Legacy

Sunshine Blue

Misty

Rabbiteye

Rabbiteye blueberries are so-called due to their appearance when ripening looking (unsurprisingly) like the eye of a rabbit when the berries are in their pink stage. Rabbiteye varieties often have larger fruits, with thinner skins. Rabbiteye varieties can grow as large as, or even larger than Highbush types. Rabbiteye varieties have the ability to far out-live other types, growing for as long as 20 years or more.

Rabbiteye blueberries are low-chill varieties and need between 450-600 chill hours. Rabbiteye blueberries flower before Highbush types, and the flowers are very susceptible to spring frosts, and containerised plants should be moved to warmer locations if frost is predicted in spring. In Canberra, as the saying goes, you aren't (relatively) safe from frosts until Melbourne cup day, although late frosts into November or even December can occur.

This year, I have two Rabbiteye varieties;

Powderblue

Brightwell

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The Fig Collection

I have always been a great fan of figs. Recently when overseas in France I would visit the market twice a week and proceed to eat two whole punnets of figs, in a single day.

It was great.

Once picked, figs do not ripen any more, and spoil very quickly. Figs when fully ripe are very soft and difficult to transport in-tact and this means that, sadly, figs are often picked a little too early for market, before they reach the maximum sweetness, and depth of flavour you can get leaving it on the tree until fully ripe.

I find fig trees themselves quite an attractive plant, with large lobed leaves, often with varied shapes. When disturbed or crushed, fig leaves also give off a beautiful aroma, sweet and figgy.

I grow the majority of my figs in a soil-less mix, and as of yet they are all quite young and unimpressive, but as they grow quite quickly they should begin to look more respectable as Spring rolls round again.


Brown Turkey

The Brown Turkey is common variety fig, not only in Australia but throughout the world. In most nurseries you come across in Australia this will be the variety stocked. Brown Turkey figs are hardy trees and form small to medium size figs that are rich and sweet. Brown Turkey figs produce a breba crop on last seasons wood in summer, and a main crop in Autumn on new growth.

My Brown Turkey has had very slow growth since re-potting in January. In the last two weeks it has begun to wake up a little, and I think I may have been under-watering.









White Adriatic

White Adriatic is a fig originally coming from the Mediterranean. White Adriatic figs form one or two crops and have pale green-yellow skin turning pale to almost white as they mature.

White Adriatic figs are meant to be particularly sweet and rich, good for jams and drying.

Like the Brown Turkey, my White Adriatic has had fairly slow growth, probably due to under-watering. In the last two weeks with extra water it has began to put out its first growth since I purchased it in January.





Black Genoa

The Black Genoa is a variety that is uncommon outside of Australia. It is a quick growing tree with medium sized sweet fruit. It is the second most common variety you will see in the average Australian nursery. It is often used as a commercial fruit here as it is prolific and easy growing with relatively hardy fruit.

My Black Genoa is the fastest growing of my container figs, putting out some sucker growth and several leaves. 




Yellow Excell

The Yellow Excell is the newest of my plants, and I stumbled upon it at Bunnings one afternoon. I have not previously seen this variety in nurseries. Excell figs ripen to a yellow colour, and are reportedly extremely sweet, rich and excellent for drying and making jams. I am looking forward to tasting this fig, probably next year.

This plant was hidden right up the back of the fruit trees at Bunnings, and was in fairly bad shape when I picked it up. Since purchasing from Bunnings two weeks ago, it has dropped a few leaves since being re-potted, and in the last week some of the buds have begun to swell, so I am hoping it will put out a little bit of growth before winter dormancy.






Mystery Figs

In previous posts you have met my latest fig cuttings, taken from a tree between Canberra and Orange, and today they sit, still looking fairly lifeless, with only a hint of a green flush in the buds waiting to put forward some leaves.

Back in December I took another random cutting from a large tree overhanging a fence in my suburb. It kind of sat there looking quite sad and unhappy with life all through January, and then in February it began to put out some leaves. Today I have great expectations for this plant, especially after re-visiting the donor fig and finding it covered in small dark figs, with a deep red interior.

Picture on the left taken at the end of Feb




Picture on the right taken mid-March

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The Canberra Climate

I was thinking tonight that I have jumped straight into this blog without any information about Canberra, where I live, or anything really about me at all.

I have been in the ACT for about 6 years now, and moved over here from Western Australia. To the uninitiated, Canberra can be quite the shock at first, especially when that first winter rolls around.

Canberra winters have a somewhat unnatural coldness to them. Geographically we are in Australian zones 1 or 2, which is approximately equivalent to zone 8-9 in the United States. Although most winter mornings will be frosty, and average between -2 to -5o Celsius, for some reason it always feels much colder than that. Or maybe it is just me! Every year Canberra routinely hits -6 or -7 at least once, and can drop as low as -9 or -10oC. During winter we have a maximum average temperature of about 12-15oC. Snow in Canberra is rare, but possible.

In direct contrast to this, summers in Canberra can be hot. Really hot. This year has been a demonstration of this, where we exceeded 40oC on at least 5 occasions, and had many days above 35oC. Historically the summer average maximums are about 30oC, so clearly 2013 is an extreme.

Canberra is one of the few places in Australia to have 4 actual seasons, and it often seems that the weather will change on the exact day as foretold by the calendar. It is on these occasions that you hear everyone throughout the city commenting on just how much it is like someone threw a switch. This Autumn, which began on March 1st was no exception, with the temperature plummeting exactly to the day. After March 1 however, this Autumn has been anything but typical with almost every day forecast between 28-31oC, and even today this trend is set to continue for at least the next 7 days. The papers are calling it a potentially record breaking heatwave, after a record breaking summer in Australia.

This year, for no other reason than 'I think so', my money is on this winter being equally as extreme, and we don't have much longer to wait to find out- one of the very first Canberran sayings I heard when I got to this fair city was that ANZAC day, April 25th is the herald for cold weather.

46 days and counting.

To prepare for winter I am currently making the most of this lingering heat, and have planted a few punnets of broccoli and brussel sprouts, to be planted out in April. I planted some peas into pots last weekend which have just today germinated, and have onions growing indoors, to be planted out in April. Next weekend, almost the Autumn equinox, I will be planting out garlic and saffron. More about these to follow in another post!


   

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