We can grow tomatoes!
Sep 5, 2021
This isn’t the best climate for growing big tomatoes using conventional advice. However as you may have noticed, cherry tomatoes grow like weeds here. Up they come by themselves; spreading from the compost, meandering out of the garden beds.
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Everyone loves a good tomato and they are so wonderfully versatile. By volume or by money spent they are easily one of the most popular vegetables sold in Australia. What you don’t want to hear is how very prone to pests, diseases and other assorted problems they are! I won’t be covering these, with the exception of fruit fly and splitting. Instead, for diagnosing tomato issues, please check the reading list for links for the Queensland Agrilink Tomato Information Kit, or DPI NSW. These contain extensive help with ID and solutions.
Most commercial tomato growing has moved into greenhouses now as this is far more controllable and therefore reliable than field-grown. Home gardeners tend to grow outside and this is the scenario I am assuming.
Summer in Bello is renowned for oppressive humidity. Under those conditions tomatoes are prone to fungal diseases. Don’t give the microbes any extra doorways into your plants. All those online tomato growing tips about pinching off this and pruning that? Forget it. Be lazy, let your plants stay whole and healthy. No unnecessary surgery, aside from keeping parts off the ground where they may be pathways for pests and diseases.
The commercial recommendation is to stake all your tomatoes. More work, yes. For better yields and better airflow (less tomato problems). Determinate types can be tied to a post, or put in a tomato cage (small diameter at the bottom!) or held upright in between string wound around them, running horizontally between posts. They can also be staked the way indeterminate types tend to be – wound up a vertical string attached to a high horizontal pole or wire, which is strung between sturdy upright posts.
Tomatoes come in two different growth habits.
Determinate (bush type) will grow to a particular size, around a metre usually, and flower and set fruit within a short space of time, ie a few weeks. This is great for making passata where you want a large volume of ripe tomatoes at one time. Not so handy for daily salads all summer long. Staking helps them stand up under the weight of all that fruit at once.
Indeterminate (vine type) will just keep on growing longer and longer, and create new leaves, branches, flowers and tomatoes in a continuous flow giving you an ongoing supply of tomatoes. These need to be staked as they have no way to support themselves. It is a weekly job to twirl the growing end of the tomato around it’s supporting string.
Queensland fruit fly
Fruit fly is a real pest in this area. In the conversations for this guide, fruit fly continuously kept getting a mention. For some reason, fruit fly don’t tend to bother cherry tomatoes. If you want to have a crack at growing larger tomatoes, fruit fly exclusion netting is recommended as essential. There are some areas (Gordonville, Valery) that don’t seem to be as prone to fruit fly and you might get away without it, but everyone else, net your toms. Greenpatch seeds down near Taree stock this netting, and there may well be other local outlets I don’t know about yet.
Fruit fly have a preference for laying their eggs in ripe, sweet, juicy, thin skinned and soft fruits and vegetables. They have a noticeable preference for large (sweet) thin skinned salad tomatoes, with a tendency to leave romas (thick skinned, not as sweet) and cherries alone. This is only a tendency. They are perfectly capable of piercing the skin and laying eggs in pumpkin and banana and citrus. Their larvae don’t grow in fruit too acidic, which translates as too young. This doesn’t stop them ruining entire crops of ripe lemons.
Queensland fruit fly are a warm season pest. They are known to become active after periods of rain or high humidity. Larvae (maggots) developing from eggs deposited in fruit result in the fruit rotting from the inside. Yuk.
The dreaded splits
You may have noticed that when it rains in Bello, it really chucks it down. 50-200mm in a day or so are unbelievable figures for most areas but perfectly common here. Even smaller amount like 20mm in an afternoon can be a flash flood in Melbourne. When it rains, the plants take up a lot of water and direct it to their fruit. The fruit grows. When it rains a lot, the fruit swell a lot and quickly, to the point where the skin splits and the whole fruit rots. In seed savers we have noticed there is a trend of the larger the tomato variety, the more prone to splitting it will be. The volume difference (and sudden-growth-in-size potential) between a cherry tomato and a beefsteak is huge. When the radius of a sphere is doubled, its volume increases eight times. That’s a lot for tomato skin to bear. There are two sensible approaches to mitigate the tendency of large tomatoes to split in our wet summer climate. One is to grow smaller ‘large’ tomatoes. Bigger is not better here. The other is to look for thicker skinned varieties if you want to grow large tomatoes as they may cope with rapid swelling better. For unconventional advice, read to the end.
Nurturing your tomatoes
It’s likely to be a good idea to raise your tomato beds up a bit so the plants don’t have wet feet. They don’t like sitting in soggy ground. Drainage and good fertility are important. Tomatoes can root down to 60cm, though most roots are in the top 20cm. Their soil should be at least 30 cm deep. Optimum soil pH is between 6.0-6.5, but commercial crops are grown in soils with a pH of 5.0-7.5.
Tomatoes are hungry plants. They are prolific bearers of fruit and feeding them well will make a difference. Plant them in lots of good compost. Weekly treats of K (potassium) to fruit well. Lots of N (nitrogen) just equals tonnes of leaves, though they do need some especially as seedlings. They need enough calcium in the soil otherwise the end of the fruit goes black and rots (blossom end rot), so add garden lime. It’s just chalk, calcium carbonate. It will also help break up the clayness of the soil and make it more crumbly which is an excellent thing. Add seaweed fertiliser regularly (weekly is good) for plenty of micronutrients, and even mulch adult plants with seaweed.
Does it need to be said that tomatoes insist on even, consistent watering to create their best juicy fruits? Excess water will kill the roots if the soil goes anaerobic (no air), as well as delaying and reducing flowering and fruit set. As we know so well here, too much water all of a sudden after fruit set results in split fruit. Flowering is reduced if the plants go thirsty. Blossom end rot (BER) becomes a problem with thirsty plants not being able to drink up and distribute enough calcium.
Tomatoes require a minimum of 6 hours of direct sunlight to flower. However, if the intensity of solar radiation is too high, it causes splitting and other problems. Lightly woven shadecloth, no more than 30% shade, will be their friend over high summer.
Tomatoes are self pollinating! Hooray, something about them is easy. The wind will enable this, no bees required. In a greenhouse situation, the plants need a gentle shake to pollinate themselves.
Tomatoes are warm-season crops. Mostly, let me explain. They are sensitive to very low and very high temperatures. Heavy frosts will kill plants, while light frosts will kill the tops of plants and can cause fruit to crack. Pollination is reduced outside the optimum temperature range of 18° to 24°C.
There is a noticeable reduction in fruit set when temperatures fall outside the range of 10° to 27°C though this varies a little by variety. Even more precisely, night temperatures should be above 10° and below 22°C. Daily maximum temperatures should be above 18°C (and up to 27°C). You can see why farmers moved tomatoes into greenhouses!!
So when do we have those temperatures?
Commercially in SEQ, the planting window is late August – February for harvesting from November – May. We are similar here.
At the moment, it’s best to sow seeds in August for early summer eating, before the high heat hits. The seeds and seedlings will need a bit of protection to keep them warm enough to reliably germinate and grow up.
If you are on the coast in a frost free warmish pocket, I’m thinking Valla Beach, Repton, I have heard of success growing tomatoes over winter. They may even do better at this time, especially the bigger ones. Fruit fly aren’t really around at this time.
As the climate heats up, we may have more success switching to sowing in January / February, after the crazy heat has dissipated and the fruit fly are winding down. This is what SEQ gardeners are doing. If it stays warm enough through to April or May, that’s long enough to get a harvest.
When to sow?
The optimum range for germination is between 20 and 30°C, but decreases rapidly below 15°C and is reduced above 35°C. Tomatoes do best started in trays and transplanted out when more mature.
Sowing to germination 4 – 10 days
Emergence to field planting 4 – 8 weeks
Field planting to first flower 3 – 4 weeks
First flower to harvest 6 – 8 weeks
(Field planting to harvest 10 – 14 weeks)
Duration of harvest 1 – 20 weeks
The following are the most salient points on getting tomatoes going from the Tomato Information Kit – well over 100 pages of detail. I’ll try and be brief.
- Fill trays evenly with seed raising mix. Plant two or three seeds per cell and cover with 6 mm of mix or vermiculite.
- Place somewhere warm and protected, with gentle airflow.
- Once germinated, the trays can be moved to a less coddled environment.
- Water trays once or twice daily and up to three times daily in hot weather. Watering should be slow to completely wet the mix. Over watering is a common mistake and causes nutrient leaching and disease build-up. Sufficient water has been applied when water is first noted dripping from the bottom of the cells.
- Apply nutrients with a high nitrogen content (for example Aquasol or Thrive) as a foliar spray when plants are about one week old. Spray once or twice weekly until plants are hardened off. Potassium nitrate can also be applied at 2 g/L.
- The most common reasons for poor transplant growth are over or under watering and over fertilising (too much N).
- Thin to one plant per cell when two weeks old.
- Seedlings are ready for transplanting into the field once they will pull cleanly out of the tray, that is when the roots have fully penetrated the mix. They should be 12-15cm tall with 3-5 adult leaves after 4-8 weeks.
- Discard any weak or diseased plants as they are unlikely to establish or produce well.
- Hardening off (gradually getting plants used to outdoor conditions and full sun) is essential for a few days at least before planting out. The greatest cause of seedling losses is planting out ‘soft’ plants that have not been hardened off as they are unable to survive the sudden change from the growing house to the field.
- A nutrient drench immediately before planting out will help plant establishment.
- Avoid planting out in hot windy conditions.
- Apply a good watering immediately after planting out.
- Keep soil moist but not wet until plants are well established. A frequent cause of poor establishment is insufficient or infrequent irrigation after transplanting. If the potting mix is not kept moist it will shrink, forming a small air layer between the mix and the soil. The roots cannot cross this air barrier so the plants will not grow. The mix is hard to re-wet once dried out so keep it moist until the roots are well established in the soil.
Almost any variety of cherry tomato is worth growing.
They all do well. Even if the fruit splits there’s so many of them you still get a crop and the plants are pretty robust and tend to grow themselves. Not so good for making passata as you end up with so much skin, but for zero growing effort you have to take some compromises. Fruit fly don’t tend to bother the cherries. Some varieties to look out for include Yellow Pear cherry, Mini Roma / Grape, multicoloured / rainbow cherry mixes, Tommy Toe, Camp Joy. My personal favourite is Green Zebra (zesty like salsa!). Tigerella is another one I’ve tried with good flavour. Most, but not all cherries are vine types.
Roma / plum / egg types are recommended as the reliable larger tomato for warm humid areas like ours.
Roma types are on the smaller end of the ‘large’ tomatoes and are a cylindrical or egg shape. They have thick skins, which seems to discourage fruit fly (it won’t stop it) and this also tends to resist splitting. Most, but not all romas are bush types.
Thai Pink Egg (bush) is highly recommended for its hardiness. It’s known to be resistant to splitting. It’s from Thailand and copes very well with humidity. Unfortunately it’s not that flash in the taste department. When eaten fresh it’s a bit like an average supermarket tomato, though I’m told it cooks up well.
San Marzano (vine) is considered THE sauce tomato and is the tomato of choice for one experienced gardener in sweltering SEQ. Stands to reason it would do well here.
Amish Paste (bush) comes recommended as thick skinned, succulent, hardy and delicious.
Roma (bush) is said to be easy and reliable here.
Large tasty salad tomatoes, that’s what we all want…
This is where it gets hard. No one knows of a reliable, tasty, large tomato that doesn’t tend to split and doesn’t tend to be targeted by fruit fly. But keep reading, all is not lost.
The large varieties that have been grown here successfully over our warm season follow a pattern of being old hardy heirlooms. In no particular order: Money Maker (known to be adapted to high humidity, vine), Mortgage Lifter (grown commercially in humid SEQ, vine), Beefsteak (vine), Black Krim (vine), were all mentioned.
The fruit fly problem may simply have to be dealt with by netting, or growing over winter when fruit fly don’t tend to be around. The large soft sweet salad tomatoes are just very tempting for fruit fly. Or maybe we need to breed our own local large tomato with a thick skin. Roma type cross beefsteak type?
For the splitting problem of large tomatoes, I have a secret gem to pass on that I’m quite excited to share. It’s a bit unconventional and you won’t find it in regular gardening instructions. It goes like this; when you plant out your tomato seedling, bury three quarters of the plant underground, not just the root system, and not just ‘up to the first set of leaves’ (which is sometimes soundly advised). Only leave one quarter of the plant above ground. Make sure you place the below ground parts at a 45 degree angle (not straight up and down). All the parts underground will grow roots and this will give your very hungry plant a really large and deep root system to feed from. It also means it will be drawing water from deeper underground and won’t be anywhere near as prone to sucking up huge volumes of surface water in one of our ‘rain events’. So the fruit will be unlikely to split. You should be able to grow any large fruited variety of tomato successfully this way here. Go and thank Paul of Barefoot Fruit and Veg for his professional secret by supporting his fresh produce stalls.
Big thanks to:
Paul of Barefoot Fruit & Veg, and Steve Smith (previously of Northbank Community Garden) and Ian Thomas (Gourmet Garden School)
To all those who chipped in their tomato gardening experience on my FB callout, in no particular order: Tim Hill, Yasmin Kellner, Jeff Holmes, Pete Bufo, Kevin Evans, Arne Nelson.
Supported by Bellingen Shire Council via the Bellingen Shire Disaster Recovery and Resilience Grant Program Funding
1. Agronomic principles in tomato production [Internet]. Yara Australia. 2020 [cited 2021 Sep 2]. Available from: https://www.yara.com.au/crop-nutrition/tomato/agronomic-principles-in-tomato-production/
2. Australian vegetable production statistics [Internet]. AUSVEG. [cited 2021 Sep 5]. Available from: https://ausveg.com.au/resources/economics-statistics/australian-vegetable-production-statistics/
3. Growing tomatoes in the Subtropics [Internet]. Love of Dirt. 2020 [cited 2021 Sep 2]. Available from: https://www.loveofdirt.com.au/growing-tomatoes-in-the-subtropics/
4. Insect pests and plant diseases [Internet]. Department of Primary Industries NSW. 2017 [cited 2021 Sep 2]. Available from: https://www.dpi.nsw.gov.au/biosecurity/plant/insect-pests-and-plant-diseases
5. Spillman R. Scenic Rim couple’s veges make motza. Gold Coast Bulletin [Internet]. 2016 May 22 [cited 2021 Sep 2]; Available from: https://goldcoastbulletin.com.au/news/gold-coast/heirloom-tomato-growers-from-west-of-the-gold-coast-are-making-a-small-fortune-as-one-of-a-handful-of-producers-in-australia/news-story/bd02683fc11d92fba6662958744b3d3d
6. Maryland Grows. Shade Cloth Can Increase Tomato Yields [Internet]. Maryland Grows. 2016 [cited 2021 Sep 4]. Available from: https://marylandgrows.umd.edu/2016/08/26/shade-cloth-can-increase-tomato-yields/
7. Tomato | Eden Seeds [Internet]. [cited 2021 Sep 5]. Available from: https://www.edenseeds.com.au/Category-Detail-Seeds?category=Tomato&list2index=2
8. Fullelove G, Wright R, Meurant N, Barnes J, O’Brien R, Lovatt J. Tomato Information Kit. Agrilink, your growing guide to better farming guide [Internet]. Queenlsland Horticulture Institute. Brisbane, Queensland: Agrilink Series QAL9805. Department of Primary Industries; 1998 [cited 2021 Sep 2]. Available from: http://era.daf.qld.gov.au/id/eprint/1655/
9. Tomato Support Methods [Internet]. Penn State Extension. [cited 2021 Sep 4]. Available from: https://extension.psu.edu/tomato-support-methods
10. Tomatoes Production in Australia (2019) [Internet]. Orchardtech. 2021 [cited 2021 Sep 5]. Available from: https://www.orchardtech.com.au/tomatoes-production-in-australia-2019/
1. Choosing a control strategy – Prevent Fruit Fly [Internet]. Prevent Fruit Fly. [cited 2021 Sep 2]. Available from: https://preventfruitfly.com.au/controlling-fruit-fly/gardeners/choosing-a-control-strategy/
2. Fruit Flies – an overview | ScienceDirect Topics [Internet]. [cited 2021 Sep 4]. Available from: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/fruit-flies
3. Fruit Fly Season is here but You Don’t Have to Spray in the Home Garden [Internet]. Self Sufficient Me. 2015 [cited 2021 Sep 2]. Available from: https://selfsufficientme.com/fruit-fly-season-is-here-but-you-don-t-have-to-spray-in-the-home-garden/
4. How to Control Queensland Fruit Fly in the Home Garden, An Integrated Pest Management Approach – Deep Green Permaculture [Internet]. [cited 2021 Sep 4]. Available from: https://deepgreenpermaculture.com/2020/03/15/how-to-control-queensland-fruit-fly-in-the-home-garden-an-integrated-pest-management-approach/
5. Penny Grose, Queensland Fruit Fly, Transition Banyule | Local Food Connect [Internet]. 2019 [cited 2021 Sep 5]. Available from: https://localfoodconnect.org.au/community-gardening/queensland-fruit-fly/
6. Queensland fruit fly [Internet]. 2013 [cited 2021 Sep 4]. Available from: https://www.daf.qld.gov.au/business-priorities/agriculture/plants/fruit-vegetable/insect-pests/queensland-fruit-fly
7. Queensland Fruit Fly – Bactrocera tryoni. In: Wikipedia [Internet]. 2021 [cited 2021 Sep 5]. Available from: https://en.wikipedia.org/w/index.php?title=Bactrocera_tryoni&oldid=1023614469
8. Department of Jobs P and R. Queensland fruit fly host fruits – Agriculture [Internet]. Agriculture Victoria. 2020 [cited 2021 Sep 4]. Available from: https://agriculture.vic.gov.au/biosecurity/pest-insects-and-mites/priority-pest-insects-and-mites/queensland-fruit-fly/queensland-fruit-fly-host-fruits
9. Dias N, Nava D, Smaniotto G, Garcia M, Valgas R. Rearing two fruit flies pests on artificial diet with variable pH. Brazilian Journal of Biology. 2018 Apr 23;79. [cited 2021 Sep 4]. Available from: https://www.researchgate.net/publication/324704720_Rearing_two_fruit_flies_pests_on_artificial_diet_with_variable_pH