Growing tomatoes in the Subtropics

Tomatoes can be tempermental to grow in our hot humid climate, pests and diseases thrive during the summer.

After years and years of experimenting I’ve finally found the key to growing great tomatoes and it all comes down to timing.

We are lucky (or unlucky depending on if you prefer sweet root veggies) enough to not get frosts over winter. It could happen, but it’s very rare, so we take our chances.

When to sow tomato seeds

There are a couple of ideal times to plant tomato seeds.

I personally find best time is late January for abundant autumn harvests. It’s still hot for us right up until the end of April so they ripen quickly. I keep them well protected from the heat and repot them a few times before planting out into the garden (see below). If you do get the odd frost, you may beat them. You still need to protect the early fruit against fruit fly but I find you don’t have to be as vigilant.

We plant seeds all through autumn as well, but I recommend to only do this if space is not of a premium as they do take a lot longer to ripen as the days get shorter.

The second ideal time is late July for Spring time harvests. Obviously the days need to be the right temperature for the seeds to germinate so check the forecast that it isn’t during the odd cold snap before sowing your seeds (you want 21 degrees).

Why not spring for summer harvest?

The worst possible thing about a failed tomato crop is having a disease in your soil. Especially if space is of a premium. It takes a long time to get rid of and it affects quite a range of plants which limits your options of what you can plant after disease hits.

In our hot humid and wet summers disease and pests love tomatoes. We have had issues with various bacterial and viral wilts, leaf curl and also russet mites during summer.

Also there is fruit fly, which even with exclusion can often be difficult to manage in the peak of their season.

If you do want to grow tomatoes for your summer salads, stick with fast growing cherry tomatoes and put them in a place that isn’t prime real estate in the patch.

How we raise our tomato seeds

Using a small pot, I plant 2 seeds in a good quality seed raising mix (we make our own). If both germinate, I cut the weakest one down. Once they get their 4 true leaves I upgrade the pot, to a bigger pot with a potting mix that includes a bit of fertiliser. When repotting, I cut off the two lower leaves and I bury the stem up to those first true leaves, this helps with establishing strong roots (I only do this for tomatoes only).

Once the seedling outgrows this pot it’s time to plant, you want to get it in the ground before it starts to flower, it’s usually around the 4-6 week mark. They are usually well established by this point and love the freedom so burst into life.

Our favourite tomatoes to grow

This changes regularly as I try new varieties. I like to grow a few in pots and containers to limit the risk of soil bourne diseases.

Here are my favourites from the past growing season.

Pink Thai Egg

Thai Pink Egg Tomato
Pink Thai Egg Tomato

If you want prolific mid sized tomato this is the one for you. We grew this in a pot this year and was not disappointed. It’s now mid June and I am still picking bowls full and it started producing in March. I’ve got some seeds here if you want to give it a try.

Black Krim

Black Krim Tomato

This is probably the sweetest large tomato I have ever eaten. It’s so impressive and full of flavour. Again we grew this in a pot and it did amazingly well. Seeds from this season are here.

San Marzano

San Marzano Tomato Seeds
San Marzano Tomatoes

I’ve tried a few ‘roma’ type tomatoes and I keep coming back to this guy. It’s prolific and tasty even as a table tomato. Seeds for San Marzano can be found here.

Honey Bee Cherry Tomato

Honey bee tomato sprawling out

A yellow cherry tomato that is super sweet. I am yet to find a red cherry that I love so in the mean time I grow this cherry exclusively. Get seeds here.

Some more of my favourites can be found here. For our full range of ever growing tomato seeds (I am always trying new ones) you can head over to the shop here.

How to contain Tomatoes

I use either cages or stringing up our tomatoes (usually to the fence in pots).

Cages we use are good quality galvanised cylinders that have spikes that you bury deep in the ground. I like them because there is zero need to really do any training.

The other method I use is stringing. So using a support high up (two star pickets with wire) I tie the tomato and wrap the string around the main stem up to the top wire. As the tomato grows I gently wind the tomatoes around the string. Some tomatoes may require additional strings depending on the type. This is handy with pots next to fences as you can string it up to the pailings quite easily.

Tomatoes strung up using star pickets, wire and jute string. Note: this planting is way too dense, I wouldn’t recommend planting so close together.

To prune or not prune

Ah a contentious issue. Some people say prune, some people don’t. I think in our climate it is important to create air flow so that’s the only reason I prune. I always trim the lower branches as the tomato grows – anything that is touching the ground.

I hope that helps with growing tomatoes in our climate. If you have any tips leave a comment below!

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