It’s difficult to move in my polytunnel … too many tomato plants and too many experiments going on, but it’s been a very exciting season so far!

The good weather has helped a lot. Even the plants that were spindly/leggy have suddenly decided to thicken-up and look like they want to show what they can do.

pH, friendly microbes and air
One of the advantages of growing in soil (including multi-purpose compost and grow bag soil etc.), is that it takes care of a number of things for us, that is, it provides a suitable pH and a healthy environment for friendly microbes that roots need to function properly.

Soil contains elements or buffers that keep pH within an acceptable range for our plants, and if the soil is well aerated, friendly microbes will grow and promote root health and nutrient absorption.

It’s a fact that oxygen in the soil and well oxygenated water added to the roots helps nutrient absorption.

We play our part of providing air, water and nutrients and the soil/compost does the rest to feed the plants and provide the healthy environment that the roots need.

Badly oxygenated water
Rain water from the water butt that smells horrible is probably full of bacteria that are likely to damage plant roots. Furthermore, if the water is taken from a roof where pigeons sit and mess on the tiles below, you probably have a water butt full of raw bird poo – stuff that your plants don’t want!

When to remove the growing tip
Tomato plants have two stages of growth – the vegetative (growth) and the reproductive stage (fruiting).
Professional growers are aware of the fact that they need to encourage plants from one stage to the other and to keep a balance that will produce a good crop of tomatoes over a set period of time. This is done by nutrition and pruning to name but two methods.

The growing tip is the most “favoured” part of the tomato plant. It is able to take (mobile) nutrients from lower leaves if there is a shortage of nitrogen or magnesium for example. You will see this happen when the lower leaves turn pale green or yellow and upper leaves look perfectly healthy.

If we remove the growing tip before the first truss has set, that is, started to grow small tomatoes, we will be sending the nitrogen meant for cell growth of the growing tip, around the plant. This will keep the plant in the vegetative stage longer, producing leaves rather than fruit.

Tomato Set
Flowers set and tomatoes appear!

However, after the first truss has set, a small burst of nitrogen is beneficial. It won’t produce heavy leaf growth because the plant has already entered the fruiting stage or reproductive stage but will encourage further truss development higher on the plant. This is particularly useful when growing large varieties that tend to run out of steam when they reach the third truss.

To sum up
It’s best not to remove the growing tip at least until after the first truss has set. You may have several trusses set before the growing tip needs to be removed, but the plant should be in the fruiting stage.

I generally allow six or seven trusses on a tall cherry variety. Five or six on a medium variety and four or five trusses on a beefsteak variety.

Too much sun!
One of the disadvantages with lots of direct sunlight is blotchy ripening, sunscald and greenback.

Blotchy ripening happens when tomatoes in direct sunlight are unable to produce lycopene because of the heat. Lycopene is the red pigment in the skin and flesh of the fruit.

Sunscald is when the skin is damaged and a pale brown papery patch appears.

Another condition is greenback which can also be caused by too much direct sunlight. The shoulders of the fruit fail to ripen – some varieties are more susceptible than others.

Blotchy ripening and greenback can also be cause by a lack of potassium (potash).

Always happy to answer questions!

Regards,
Nick

5 Responses

  1. Douglas
    | Reply

    Hi Nick…..dont know whether this is a problem or not,but on my ailsa craig plant the first truss hasnt set any fruit at all and doesnt look as though its going to,however the second and third trusses have.Should I remove that first truss ?

    • Nick
      | Reply

      Hi Douglas,
      I had the same problem on one of my plants last season and I just left it. I think eventually it did produce one or two small tomatoes but nothing of value so probably best to remove it with a sharp blade.
      Regards,
      Nick

  2. Rhys Jaggar
    | Reply

    Nick

    Reading what you’ve said about removing the growing tip, I was wondering if this has an effect on cherry varieties of making their trusses become longer and carrying more fruit??

    My Sungold and Apero plants are developing beautifully, but each truss has only 14 tomatoes on a present, so stopping at 4 or 5 isn’t really a very productive solution.

    So do you expect the trusses that have formed to compensate for no further new ones by getting longer, producing more fruit as a result??

    As for rainwater, I noticed that when my butts were still topped up, the rainwater stimulated growth fantastically. Now we’re near the bottom due to the drought in June, growth is less prodigious, but it may simply be that plants are reaching fruit phase. They are considerably smaller than last year though, when plants kept growing all through July and were only pinched out at the end of July.

    • Nick
      | Reply

      Hi Rhys,
      I would let the cherry varieties go on to at least six or seven trusses – if you have only 14 tomatoes on the lower trusses (though that’s still good!), you may be able to allow eight or nine trusses and prune any stragglers at the end of a truss that are slow to set or grow. I don’t expect the trusses to grow more flowers once they’ve reached a certain stage – I suspect that most varieties will try to make side shoots if they have excess energy.
      The amount of flowers produced can be temperature related to growing conditions earlier in the season. It’s been shown that young plants that have been given cool growing conditions for a small amount of time (cold treatment) produce more flowers – amazing though that is!
      We are so used to poor to average weather and growing minimum trusses, that when we have really good weather it puts us in a new situation. If the weather carries on like this, it will be an exceptional season.
      Water butts are great as long as the water contains some oxygen otherwise anaerobic bacteria take over and the water becomes stagnant. A good splash around can add oxygen – some people use a tropical fish tank air pump!
      Regards,
      Nick

    • Douglas
      | Reply

      Rhys…..same thing is happening with my 2 sungold plants.Last year the trusses were twice as long with far more flowers and fruits.However my black opal cherries have trusses even longer than my sungolds of last year.So make of that what you can.Ive given up on the pecularities of plants season by season and basically do my best -and hope for the best.On a side note after not seeing 1 bee in the greenhouse last year ,im now literally inundated with them ,whether that adds or detracts something from the mix Im not really sure.I was under the impression that the bee population was decreasing…maybe it only appears to be so cos Ive got most of them lol.

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