Anyone who has been reading these newsletters for a while, will be fully aware of the issues concerning over-feeding tomato plants.

However, I think it’s useful to go through some of the points again for those who have recently joined and also to remind ourselves why too much food in the soil is best avoided and to resist the temptation to over-feed.

Mineral nutrients (in tomato food) can build-up and crystallize in the soil and become toxic for roots. This can send plants into stress. Slow growth and very curly top leaves are two symptoms.

Too much nitrogen just before the plants come into flower can cause a delay in flowering and even cause plants to abort their flowers. Sometimes you may see the flower buds shrivel-up and die away before they have opened.

However, the main problem caused by over-feeding is that it usually causes nutrients to become “unavailable” to tomato plants.

The irony is that the more we feed our plants, the more it becomes likely that some nutrients are blocked and become unavailable to our plants, through their roots.

This is called “nutrient lock” or “nutrient block”.

For example, too much potassium (potash) may cause less calcium to be available resulting in Blossom End Rot.

The best way (as I’ve mentioned many times) is to keep nutrient application of the soil to a minimum and feed calcium and other nutrients such as magnesium or iron, by means of a foliar spray.

For those of us in the UK who are about to experience some reasonably good weather over the next few days, it’s good to remember not to over-feed our plants. Also, let some air back into the soil if your plants have been stood in the rain for the last three months!

Here are the main points again:

  • Nutrient build-up can cause stress
  • Too much nitrogen can delay flowering or cause buds to be aborted from their stems.
  • To much plant food in soil can cause some minerals to become “locked” and unavailable to plant roots.

So, if you want to give them a bit extra – feed them through their leaves.


3 Responses

  1. Ro
    | Reply

    Hi and i try to grow all types of tomato each year and still learning ?, this year i found that by finding the leaves ready to curl up and crucify i needed to add Calcium as the fruit was beginning to show rot on the underside of fruit, Immediately i gave the plant some Calcium by breaking up a few calcium tablets [ roughly 3 tablets to 6 plants] dissolving the tablets first allowing to cool add water and spray.
    Followed up next day with egg shells around base and will be watching the leaves in future as this will give clear indication of the health of the plant.

    I love to grow and eat tomato [mostly give away]

  2. David
    | Reply

    I wish I had some Tomatoes left to feed! We have lost every single plant on the allotment to blight! I had 4 different varieties I’d planted this year & in spite of the cold, wet weather since planting out most of them were doing very well & a few plants were even setting their first trusses.

    One was a heirloom variety the others were F1 hybrids – made no difference – they all succumbed! ;-((

    What can I do in future years to avoid a recurrence of death through blight? Do you have any organic ideas?

    • Nick
      | Reply

      Hi David,
      Apart from spraying with Systhane or Bordeaux Mixture, there is very little to stop outdoor plants from getting fungal diseases. However, there is a new product that will be on the market soon (I hope) called Serenade. It’s a bio-fungicide and protects by covering the leaves and roots with friendly fungi.
      You’ll find out more if you Google bio-fungicides.

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