Tomato Trial – Part 2

growing tomatoes from seed

How to grow tomatoes part 2. Those of you who have been following our little tomato trial will be pleased to know that the seedlings have made it through their first 3 months of life. If you haven’t been following it you can catch up here. 

The short version is we’re growing 5 favourite heirloom American varieties of tomatoes and trialing a range of crop protection methods against the dreaded tomato pysllid bugs. We’ve raised 15 plants in total, 3 of each, and we’re comparing organic protections, chemical spray and no sprays to see how the varieties and protection methods perform.

growing tomatoes

We’ve bought in some nice new bug free soil and we’re going to grow them in the bags, propped up in recycled supplement bins with the bottoms cut out.  The bins are lined up in strategic spots around the garden but I know the pysillids will find them as I’ve tried this method of growing in pots away from the main garden before and the crop still gets infested.

Labour weekend is the traditional time to plant out your tomatoes across much of the country but the night time temperatures are still too cool in Nelson to reliably plant out then.   A couple of weeks later is a safer bet, but even now we still have snow on the ranges and an overnight temp of just 3° C last night!  Just as well they were well hardened off.   Ideally you’re looking for a regular night time temperature of around 12°C before planting out.

Plant your tomatoes deeply, up the stalk to the first leaves, and they will grow roots along the planted stalk, giving you sturdier plants.  Give them some tomato fertiliser, rich in potassium, and some well rotted manure mixed through your planting soil.

chemical sprays

For our chemical weapon we’re using the only spray on the market approved for use on the tomato potato pysillid bug.  It is a spray called “Maverick” which is a Yates product containing the chemical tau-fluvalinate, a synthetic pyretheroid which is not as bad on bees as some chemical sprays, but still toxic to bees when wet.  The recommended spray program for pysillids is every  7-14 days.

spray free tomatoes

These five little members of our trial are going it alone, just lots of water, sun, good seaweed fertiliser and some tomato food from time to time. Can’t wait to see how they go compared with their pampered counterparts in the other bins.

organic sprays for tomatoes

For our organic protection we’re trying a range of options.  Neem granules, neem oil, pyretherum spray, soapy water (an old method for killing aphids), and a fancy new crop protection mesh.

crop protection mesh

This fine woven mesh cover is being evaluated by the Future Farming Center at Lincoln University.  It totally encloses the crop and is apparently effective against fine insects like carrot fly and my pysillids as well as birds and weather damage.

Rain and watering will penetrate the mesh and the only time you need to remove it is for harvesting and weeding.

You’re supposed to dig it in around the edges of the soil or pin it down but I’ve just trussed up one of the drums with tight twine.  If the mesh lasts for 10 years as claimed, it would be a cost effective, if cumbersome, organic protection method.

So we are all set for the next phase of the trial.  We’ll be spraying every week, watering well every couple of days and looking forward to seeing how each variety grows.


Update Month 4:

Well, the tomatoes have been planted out for nearly a month now and I’m somewhat surprised to inform you that the best performing ones are the “no spray” crew, closely followed by the ones sprayed with “Maverick” chemical spray.

Sadly, the organic spray tomatoes are showing variable results.  Of the 5 organic pest control tomatoes the neem granule, soapy water and crop protection mesh tomatoes are all flourishing but the neem oil and pyretherum spray tomatoes are really turning their toes up. I’ve checked that my spray dilutions are correct. I can’t see any psyllids on them but I can’t work out why these two are doing so poorly while their immediate neighbors are flourishing.

They really look as though the spray is burning them. I’m spraying in the early morning before the sun is up and I’ve gone and sprayed a non-trial tomato in the main garden to test my theory that it is the spray that is at fault so we shall see.

tomato pests and diseases

I haven’t seen many pests yet.  Last week we had an aphid infestation on the soapy water organic spray tomato but after spraying those have gone and not returned.  A few white fly on the neem granule tomato but nothing major yet.

Between the varieties, there seems to be no marked difference in growth.  Mortgage Lifter and Black Krim are marginally more vigorous than the other varieties at this stage. The plants sprayed with Maverick are the smallest while the ones sprayed with nothing are the largest. All of them are just starting to set their first flowers.

tomato flowers

I’m removing the laterals and tying the tomatoes up each week at the moment to keep the plants growing upright with not too much side foliage growth. removing laterals from tomato plantsI like to describe laterals as the bits that grow in the armpits of the leaves coming off the main stem – everyone seems to understand that.  You want to get rid of laterals on these upright staking tomatoes.  It is not so important on cherry tomatoes which can ramble all over the place, but on these larger fruited tomatoes, the weight of fruit on unsupported laterals can snap the plant and laterals also produce more leaves and less fruit.

I’ve also removed leaves below the first flowers and thinned dense upper foliage, leaving just enough to give a bit of shade to the developing fruit.  It seems sacrilegious to nurture a plant from seed for 4 months only to take to it with the secateurs and remove over half the leaves but now is the time the plant needs to put its energies into growing fruit and it also increases air flow around the plant which reduces the risk of fungal diseases. Always cut clean to the trunk or joint, leaving no stubs that can get infected with fungal diseases.

taking leaves off tomato plants and tying up-

Check the ties on your plants to make sure they’re not too tight as the trunk grows and keep adding ties so the wind doesn’t snap the top out of your plants. I use these adjustable rubber ties which are nice and soft on the trunk.  You can get several years use out of them too.

I’m watering evenly every couple of days. It is important not to let your tomato plants dry out as the fruit is forming or the skins thicken and then later on, they can crack as the fruit swells.

Update Month 5

We’re approaching mid-January and it is 5 months since the tomato seeds were sown.  Here is a round up of how each of the five varieties are faring.

heirloom tomato trial mortgage lifter

Mortgage Lifter continues to be a vigorous plant and is slightly ahead of the rest. It is setting reasonable amounts of fruit on all plants.

aunt rubys german green tomato plants

I don’t think I’ll get much off the Organic Aunt Ruby’s but the no spray and chemical spray plant seem to be doing well. Not as many fruit as the other varieties but what there is large.

Paul Robeson Tomato plants-01

Possibly the most impressive of all the varieties at this stage, Paul Robeson plants are vigorous and are setting large fruit, but not that many of them.

Cherokee Chocolate tomato plants-01

The poorest of all the varieties in the trial. The organic one suffered “burn” from the early sprays, the no spray one I inadvertently lateraled the top out of it and it has gone into a major sulk, the chemical spray one is doing OK and has a couple of fruit on it.

Black Krim tomato plants-01

I have high hopes for Black Krim, having read so many great reviews of this tomato. All three plants are looking good and setting some fruit. The no-spray one is doing the best.

Pests and Diseases

On the pests and diseases front, we seem to be remarkably healthy. The earlier white fly and aphid infestations were dealt to on the organic spray plants.  The no-spray plants don’t have any sucky pests on them and there is no sign of the dreaded pysillid yet – despite the potato crop up near the top shed being riddled with them. Touch wood it stays up there.

I’ve removed a few lower leaves with rust on them and it is about time to give the leaves another thin out on some of them as they’re getting a bit overgrown and lush.

One thing that is puzzling me is that a lot of the flowers seem to be breaking off just above the neck of the blossom. I thought it was the birds eating them but a bit of research tells me that sometimes a plant will drop blossoms as a self self-regulating control mechanism for a variety of reasons including:

  • lack of nutrients and/or water
  • periods of high humidity
  • blossom not able to open for pollen transfer and pollination

tomato flowers breaking off

I’m feeding and watering well so I know that is not the issue. The blossoms seem to be opening just fine too so no encouragement required there. We did have a period of high humidity over a week around Christmas so that may have caused it although later blossoms are dropping also. The problem is the same across all varieties and spray programs.

I’m wondering if the plants know they’re in a bag rather than soil and feel like if they set a heavy crop they may topple over? The main garden tomatoes are a month behind the bag ones but there is no sign of this blossom drop on their early flowers.

Month 6 Update

Well after consulting with Miles from Garden Organics and my neighbour Brian, I think I’ve worked out why the blossoms are dropping and the leaves are cupping. The soil is getting too hot. I’ve positioned the bags in sunny areas of the garden and they seem to think the roots are overheating. This is putting the plants under stress which is why they’re not setting as much fruit. Miles says he gets leaf cupping in their tunnel house in hot weather when the roots get too warm.

Definitely spoke too soon on the lack of pests and diseases. Since then the marauding hordes of pests and diseases have arrived, all except the dreaded pysillid which thankfully still hasn’t put in an appearance.

We have had caterpillars on everything except the chemically sprayed tomatoes and the tomato with the crop protection mesh around it. After an entree of leaves they settle down in the tomato for their main course. All the organic sprayed plants have caterpillars too.

We had some rain (finally) which was great but the grow bags have a wetting agent in the mix to keep moisture in the soil and so they soaked it all up and we got a lot of splitting and cracking in the tomatoes that were nearly ripe. We also got a bit of blossom end rot (photo on the right below) which is also a sign of uneven watering or lack of calcium uptake. I put it down to the watering because they have been getting tomato fertiliser.

tomato pests and diseases

Now we are getting down to the business end of things I hope these pests and diseases can be kept at bay long enough for us to get some kind of harvest.

And yes we did. To read the final installment in our tomato trial trilogy click here.



  1. The woven mesh looks interesting but what about the bees? They won’t be able to get in either. 🙁

    1. Yes I thought that too Carol – I might have to get in their with my paint brush and dab a bit of pollen around!

  2. You don’t have to worry about the bees with tomatoes they are wind pollinated or just flick the string or cane to release the pollen.

    1. OK Leigh, good to know – thanks for sharing – will give the stake a shake 🙂 and get that pollen moving around.

  3. Was wondering what companion planting plants you were using?

    1. Hi Stephanie, I’ve planted some basil underneath the Black Krim tomato in the organic sprays section and it is thriving. I’ve heard Basil loves tomato and not just in the kitchen so I’m giving it a go.

  4. You might like to try this idea. when growing tomatoes think VINE not BUSH unless it’s a cherry type tomato, so I take off ALL the leaves up to the setting truss of fruit (no leaves below a fruit truss) keeps the air flowing and lowers humidity, also easier to see any pests or disease. Remember you are growing fruit not leaves. Works for me. the cherry type tomatoes I just let them go for it, but keep it a bit tidy underneath the bush. I grow in bags in a tunnel house in South Otago and have NO pests or diseases whatsoever, also no chemicals used.

    1. Great advice thanks Wendy, I’ve done that with mine – think I may have over done it actually – they’re looking pretty sparse but lots of clusters of toms hanging there ripening. All we need is some more summer heat. How often do you water your bags and are they one plant to a 40ltr bag of compost?

  5. Can you buy the mesh? If so, where? Have looked on line but have not managed to source it.

    1. Yes Lincoln uni bio husbandry unit sells it – that is where I got mine a couple of seasons back.

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