I’m often mocked for my obsession with growing a Christmas tomato. But I’m not the only one who strives to achieve this gardening glory.
Every spring, many hopeful gardeners plant precious tomato seedlings into the garden with the hope to develop and ripen a tasty tomato before Christmas. It is a tough feat to manage and can be seen as a badge of honour to some gardeners. You see, for warm-temperate growers, such as those in Melbourne, it takes careful planning, good attention to detail, a bit of experience and plenty of luck to ripen a tomato before Christmas. It took many years of trial and error, combined with meticulous record keeping and a lot of patience, but I mastered the art of growing Christmas tomatoes in Melbourne. There was always some seasonal variability, but in my last few seasons of growing in Melbourne, I would often pick my first ripe tomato at the end of November.
In 2019, when I announced to friends and family that my family and I were moving to Kyneton (a small town 80 km north-west of the city in a cool-temperate area) many of them scoffed “You’ll never ripen a Christmas tomato in Kyneton”. I had to admit, it seemed unlikely too.
Yes, I did have to re-learn gardening all over again. But I had experience on my side, and I had phenology.
By observing phenological indicators such as the flowering of the Silver Wattle (Acacia dealbata), I managed to track the differences in seasonal climates and quickly adapt to my new gardening climate.
In my first summer of gardening here, I ripened my first tomato on 8 December 2019.
Ripening a cherry tomato before Christmas is easy
Cherry tomatoes such as Broad Ripple Currant will develop and ripen much sooner than larger slicing tomatoes will. I see ripening slicing tomatoes before Christmas as the true challenge. So to me, the first tomato to ripen here in Kyneton didn’t really count. Low and behold, just 8 days later the first slicing tomato was picked.
To prove it is not a fluke, I’ve managed to ripen a tomato before Christmas every year that I’ve been here. There’s been plenty of seasonal variation, for example in 2021 I only just managed to pick a ripe cherry tomato on Christmas eve. Last year was my most impressive effort, with a ripe tomato harvested on 25 November 2023.
“What a load of hogwash”
I often have such achievements dismissed by fellow gardeners.
“Who cares about Christmas tomatoes, what’s the big deal anyway?”
Or more often
“Yeah, but I bet you use a greenhouse, it doesn’t count if you use a greenhouse”.
Apparently, there are some unwritten rules in this achievement. According to some (usually those who haven’t grown a Christmas tomato) using a greenhouse is cheating. I’m not so sure about that. I don’t feel there are such rules. In fact, the more effort I go to ripen a Christmas tomato, the more rewarding it is. Some folks go to all sorts of lengths, carting seedlings outside every day to chase the sun and then bringing them inside of an evening to help protect them. This can go on for months. Some gardeners construct elaborate cold frames, invest in expensive greenhouses, heat mats and all sorts of infrastructure.
Others buy advanced seedlings from nurseries, just on planting time. Does it even count if you don’t sow the seeds yourself? I reckon it should. If you are having a go at growing your own food, then it doesn’t really matter.
I have two greenhouses and I hardly ever use them
Last year, I purchased a propagating heat mat to better analyse how useful such a piece of equipment may be. I decided that because I now owned the equipment, I would continue to use it. However, if you don’t already own a heat mat, then please have a read of this blog post before deciding if it is a wise investment.
This year I’ve already sown most of my tomato seeds and placed them on the heat mat to germinate. Once they start growing their true leaves, and really bending towards the window to chase the light (phototropism) then I’ll transfer them to my greenhouse.
I’ve already discussed how little I use my greenhouses here. I do use them a bit, to grow on my tomato seedlings and to take advantage of the automated watering system. But that’s about it. In most circumstances I don’t see a greenhouse as a wise investment for a backyard gardener. There’s plenty of cheaper alternatives to greenhouses that don’t take up as much garden space, if any (more on that here).
I do use a heat mat, and yes, I use a greenhouse to help me grow a Christmas tomato in Kyneton. But I will clarify that the plants have always been happily growing in the ground (or raised garden bed) for some time when the tomato has ripened.
I’m sure it can be done without a greenhouse
I’m not motivated by the naysayers in this quest. As mentioned above, I’m not concerned about any rules that detract from my achievements to grow a ripe Christmas tomato. I’m happy enough with the methods that I use to push the boundaries of nature. Instead, I’m motivated to show you that it can be done. That you don’t need to invest hard-earned money in expensive infrastructure such as greenhouses and propagating mats to grow food. I want to inspire and support you to give it a crack.
This year I’m running a side-project to grow a Christmas tomato using only rudimentary equipment. It’s going to take more effort than my usual method, but I’m sure that it can be done.
I’m going to document my quest right here, by adding regular updates to this blog post. Just like the Fool’s Garden Experiment that I ran last year, I hope that you find it useful and inspiring.
Experience is the key to growing a Christmas tomato with only basic equipment
In Melbourne, I’d sow my tomato seeds into small pots and place them straight into the greenhouse to germinate. However, here in Kyneton, the winter temperatures are too cold to allow the seeds to germinate. Prior to having a heat mat, I would need to bring the pots indoors and place them by the fire. This would allow the potting mix to warm to around 20 degrees and stimulate seed germination.
In my early days of running the business I didn’t even have a greenhouse. I used all sorts of different methods to start my tomato seeds. In one rental property we had an open fireplace. I would light the fire every evening to keep us warm. The next morning, I would scrape out the ash and place the trays of seeds on the warm bricks to assist germination. I’ve used cold frames made from old shower screens salvaged from hard rubbish. I have tried and sometimes failed to germinate tomato seeds using many different methods. I’m going to use some of the knowledge gained in my efforts to show you that it can be done with only the most basic of equipment.
You might not have your own experience to call on, but now you’ll be able to learn from mine.
What’s most important in this quest?
There’s several factors to focus on, if you are also going to attempt this feat:
- Timing (of seed sowing and transplanting)
- Genetics (choice of varieties)
- Soil Temperature (of both the pots and the soil that you transplant into)
The clock is ticking but I work backwards
There’s certain aspects of growing food (and life) that you can’t get around. Time flies and patience is a virtue. Timing is critical to successfully growing food (more on that here). You’re going to need to work out when the optimum time is to sow your seeds. For me, I work backwards.
I know that here in Kyneton, I’m going to transplant my tomato seedlings into the garden in early to mid-November. When I do transplant them, I’ll need them to be large, healthy and well established. Most importantly, they’ll need to be flowering and may even have fruit already set on the plants.
In Melbourne, the timing for transplanting my tomatoes was different. In the past, I would transplant my tomato seedlings into the garden around the time of the AFL Grand Final, that is in late September or early October. At this point, the seedlings didn’t need to be quite as big as my plants in Kyneton need to be when transplanted, but in both instances, they do need to be flowering.
It is very important that the seedlings are flowering before transplanting into the garden. If they aren’t and they are transplanted into well cultivated soil that is rich in nutrients (particularly nitrogen) then they grow, and they grow very big. This is usually seen as a good thing, but come February, you’ll be scratching your head and wondering why you have a giant tomato plant, that looks very healthy, but isn’t developing any fruit.
Mollycoddled tomatoes such as this are in no rush. They’ll get around to fruiting eventually, but for now, they are focussed on taking advantage of the great growing conditions.
On the other hand, a plant that is stressed has a greater sense of urgency. Time is ticking for the stressed little plant. Its biological clock is ticking, it needs to reproduce quickly to ensure that the genetics are passed down to the next generation. For the home gardener, this attempt to reproduce is what we are after – flowers, which lead to tomatoes!
Transplanting already flowering plants into nutrient rich soil results in the best of both worlds. The plants grow strong and healthy AND they continue to flower and set fruit all summer.
So, I need to work backwards. If I aim to have slightly stressed tomato seedlings, that are beginning to flower at the time of transplant. Then I need to work out when to sow the seeds in pots and when and how to stress them. This is where my previous experience comes in.
A little bit of stress is a great thing
The key with stressing your plants is to only stress them slightly. Too much stress and you’ll set your plants back too far or may even kill them. There’s two effective ways that I know to slightly stress a tomato seedling:
- Allow it to become slightly pot bound,
- stop watering it until it becomes a bit wilted and drought stressed (then irrigate to revive them).
I choose the former method as although it is trickier to get the timing right, once I worked it out it became easy to do.
Consistency is the key
I know that when I use a particular sized pot filled with a particular potting mix that I get very consistent results. Through trial and error, I worked out that in Melbourne, I needed to sow my tomato seeds at the end of July, directly into 7cm square pots filled with Nature’s Soil potting mix (which performed well in my potting mix trial). These pots were placed into my particular greenhouse and they would germinate and grow to be just the right size for transplanting into the garden at the end of September. Not only that, but they would exhaust the nutrients in the potting mix at just the right time to stimulate the development of flowers without overly impacting the health of the plant.
If I used a different sized pot or different potting mix, then there may be more or less nutrients available to the seedling so the timing may need to be altered.
Generally bigger is better when it comes to greenhouse performance, but the material it is constructed from can also have an influence. If I used a different sized greenhouse, then the temperature may not hold as well and the timing may need to be altered.
By consistently using the same pots, potting mix and greenhouse I was able to fine tune the planting of my tomatoes in Melbourne.
But then I moved to Kyneton, and I had to adapt.
Fortunately, I (literally) picked my greenhouse and moved it with me. I also have access to the same pots and potting mix. So for me, it wasn’t such a shift in process. Just the timing needed altering.
It’s much colder here and the greenhouse performs differently in this cool-temperate climate. In fact, it’s so cold here that the tomato seeds need starting indoors. The greenhouse doesn’t get warm enough in July to stimulate germination. I also have an extra month to wait before I can transplant them into our cooler soil.
I now know that in Kyneton I need to sow tomato seeds in early July and start them indoors. Then I transfer them to the greenhouse to grow on and become a little pot bound and stressed (usually around the start of October). At that point I pot them up into even bigger pots to grow on further, ready for transplanting in November.
Genes play a big role too
Like most aspects of growing food, variety selection is critical (more on this here). The genetics of the tomato plants play a huge role in early ripening. Some varieties will ripen much earlier than others. Focus on growing early ripening varieties if you want to grow a Christmas tomato. Some of my favourite early tomatoes are:
Broad Ripple Currant, a small yellow cherry tomato that is the most cold tolerant that I know of.
Jaune Flamme, a golf ball sized orange tomato that is very early. It would suffer terribly from fungal diseases when I grew it in Melbourne but is one of my best performers here in the much drier summers of Kyneton.
Stupice, is the earliest ripening slicing tomato that I’ve grown. It has good disease resistance and crops well.
In this experiment I’ll focus on growing Jaune Flamme and Stupice.
Soil temperature matters
Keeping young seedlings is going to be a challenge. I’m going to start the seedlings next to the fire to keep the potting mix warm. Then I’m going to transfer them to a very small, very inexpensive and very portable greenhouse: an opaque plastic tub.
The plastic tub will be moved around to try to optimise the seedlings’ access to warmth and sunlight. If you are following along at home and want to give this a go then the following locations are good choices:
- On top of the hot water service
- In a large, north facing window
- Near the heater, if there’s good access to sunlight
- Some of you in Melbourne and other warmer climates, may even be able to leave the tub outside as long as the lid stays on
My biggest challenge with all of this is remembering to keep the plants watered. I typically rely on automated watering systems as life is busy and I’m prone to forget such routine activities. Keeping the lid on the opaque tub will help reduce water loss to the environment and keep the humidity high inside the tub.
Last year, my Fool’s Garden experiment showed that timing played a big role in success of growing tomatoes. Transplanting early stunted growth, delayed ripening and reduced yields of tomatoes (but had different impacts for other vegetables). Come November, I’ll be paying close attention what’s going on in the garden to try and work out the optimum transplant time.
So, what’s the plan Stan?
Here’s a quick methodology for the experiment:
- I’ll sow tomato seeds in 7 cm pots and place them by the fire to germinate.
- When they’ve germinated and in need of more light, I’ll relocate them to an opaque plastic tub.
- That tub will be moved around to different locations to try to optimise light and warmth.
- As the plants grow they may be upgraded to bigger pots or opaque tubs
- Eventually they’ll be transplanted into the garden into some raised garden beds
- Fingers crossed, I’ll pick a ripe tomato from the plants before 25th December 2024.
Stay tuned to my newsletter for updates as they occur.
Update 22 July 2024
I sowed the tomato seeds on July 9 (when the Wood Ducks began investigating nesting sites on our property). They germinated on July 20 and are growing well. I will soon transfer them to the opaque tub to further support their growth.
Update 2 August 2024
The seedlings are now starting to bend towards the window to chase the light (phototropism). So I’ve now placed them in the plastic tub and am transferring them outside into the sunshine each day.
In the evening, as the temperature drops and the sun dips, I bring them back inside to keep warm.
Update 30 August 2024
Now that they have germinated and grown a few true leaves, I have thinned the tomato seedlings by removing all but the strongest plant from each pot. Whenever I remember (which is less often than I’d like to admit) I’m taking the tub outside on sunny days. But otherwise, the tub sits near the fireplace, with a bit of sun coming in through the north-facing living room window.
The plants are getting bigger and highlighting how low-cost, simple solutions can also be the some of the best. You don’t need gimmicks to grow your own food. Despite the low-cost, no-frills approach, I think these tomato plants are doing better than my main crop of tomato plants in my greenhouse.
Update 30 September 2024
The tomato plants have outgrown their current tub. They are also looking quite pale and “leggy”. This is a sure sign that they are not getting enough light.
The temperatures are slowly increasing and the overnight minimums are not as severe as they were a few weeks back. So it’s time for action.
Today I moved the two Christmas Tomato plants permanently onto our deck. They are still under the shelter of the eaves, so any frosts shouldn’t affect them. I’ve upgraded to a larger tub and staked the plants to help with the “legginess”.
There’s still no sign of flower buds appearing, but as soon as they have, I’ll be potting these two plants up to give them more room to grow.
The plants are as big as their siblings growing in the greenhouse, but the greenhouse plants are already developing flower buds. The race is on!
Update 24 October 2024
I (almost) have flowers! The Stupice plant has flower buds on it. The Jaune Flamme plant shouldn’t be far behind.
The plants are now crammed against the top of the larger tub. However, both plants seem much more spindly and less bushy than the rest of my plants thriving in the greenhouse.
I usually wait until flower bud formation before potting my tomatoes up. I potted up the main crop of greenhouse tomatoes a few weeks ago, when they started flowering. Now it’s finally time for these two plants to go up a pot size.
Potting them up will give them access to more soil nutrients. The leaves on these plants are looking a bit pale. I think they need more light than they are getting in the spot under the covered deck. I’ve moved them to a sunnier spot, but I’ll need to keep a close eye on them during hot days to make sure they don’t cook. I’ll also need to protect them better during any cold nights that lie ahead.
Update 5 November 2024 - Cup Day Planting
It’s Melbourne Cup Day. The soil has warmed up, and it’s time to get planting. I planted the two experimental plants alongside my main crop of tomatoes. The main crop, grown in the greenhouse look stronger, healthier and slightly more advanced than my two plants growing in the tubs. I’m certain the greenhouse plants will fruit first, but hopefully the experimental plants will still come good in time for Christmas tomatoes.
