Feeding Tomatoes – back to basics

My cupboards are full of every nutrient and additive booster under the sun, or at least it seems like it!

Yet if we want to keep it simple, what are the fewest products we could use and still get excellent results?

First on the list is tomato food – not surprisingly!

Given when flowers start to set fruit, this is flower-power food containing potassium (potash) which will give plants a helping hand to produce flowers and fruit.

Chempak Standard Tomato Food contains macro and micro nutrients and calcium to help avoid blossom end rot.

Tomato Food

For me, the days have gone when I would rely on the roots and soil to provide all the calcium the tomatoes need. These days I foliar spray with calcium and spray the fruit too.

However, it’s not just avoiding BER that plants need calcium for, they also need it for general growth.

Check out the contents on the side of Tomorite tomato food – do you notice anything missing?

Chempak Calcium is excellent for use as a foliar spray.

Chempak Calcium - feeding tomatoes

Ground egg shells and indigestion tablets are often mentioned as ways to apply extra calcium to the soil.

The problem with egg shells is that they take a long time to dissolve and break down in soil.

Calcium Carbonate, the main ingredient of indigestion tablets, is OK to apply to soil but will raise the pH level and that could cause difficulties for plants to absorb other nutrients.

It’s my method to apply only tomato food to the roots and use foliar spraying for almost everything else.


Over-feeding, especially with nitrogen, as the flower buds begin to form can cause them to shrivel and die away – a kind of “blossom drop” or “bud fade” in this case.

Making sure that plants get everything they need before the flowers set fruit and start on the tomato food, is why a two part feed is so helpful.

Vitalink Earth, Bio Grow and Fora Duo are two part feeds.

A two part feed could be accomplished with Miracle Grow and Tomorite, but again, check out the contents of Miracle Grow – do you notice anything missing?

Some nutrients are mobile and some aren’t!

Mobile nutrients such as nitrogen can move around a plant as required. For example, if the top leaves need more nitrogen they can get some from the lower leaves. This is why lower leaves often look as if they have never been fed – the top leaves have taken their food!

Immobile nutrients like calcium aren’t able to move around a plant’s system so freely. The only way the upper leaves or fruit are able to get some is by way of the roots, and if the balance of nutrients or pH in the soil isn’t right, they may not get any at all, or have to wait a long time for it!

That’s one reason why foliar feeding is so useful – and root feeding can complicate matters.

So to sum-up

  • Give tomato food to roots, after flowers have started to set fruit
  • Apply calcium as a foliar feed weekly, after flowers have started to set fruit.

What if my tomato food already contains calcium, do I still spray?
In my experience, the only way to avoid blossom end rot is to spray. The soil/compost we use varies so greatly (in nutrient levels) that we don’t really know exactly what’s going on down below, so it’s better to be safe than sorry.


Making sure that soil in containers and grow bags is uniformly moist will ensure that roots have access to all the nutrients in your soil – roots cannot absorb nutrients from patches dry soil beneath the surface. A wetting agent can help avoid this problem.

A two part feed is better than a one part feed because it also supplies plants with nutrients up to the point of fruit set. This is the period of growth where over-feeding is an issue.

I could mention encouraging friendly microbes in the soil – but I think I’ll stop here!

Back To: Feeding Tomatoes Part One

8 Responses

  1. douglas
    | Reply

    Im seriously considering getting rid of my tomato plants this year……no sun ,plenty of rain and dull days…..nothing seems to be moving at all..few toms half a marble size on 1st trusses ….dont even know if they are worth wasting tomato food on……cucumbers the same …had two mini cucumbers picked and eaten,the rest are puny about 2 inches by half inch…….maybe if i move to afghanistan?

    • Nick
      | Reply

      Hi Douglas,
      I know how frustrating it can be – a poor summer makes growing tomatoes much more difficult or even impossible if you grow outdoors in the rain!
      If the weather is like this each summer, I think I’ll start growing rice!

  2. Mark Downing
    | Reply


    I looked on the label for Vitax tomato food and was disappointed to see no mention of calcium (your favourite micronutrient) or magnesium (mine). FWIW Phostrogen has 1.5% Mg but no mention of calcium.

    I suppose that in hard-water areas people using mains water for irrigation will be supplying their plants with calcium anyway – look in your kettle!

    Thanks for keeping us informed.

  3. Joseph James
    | Reply

    Thank you for the advice regarding my method of growing my plants in pots and standing them in 3″deep trays filled with water to save watering so often.I have lost 2 plants and believe that your concern about overwatering may be the answer.I have emptied the trays and now allow the plants to stand in them and only water when needed.
    I feed the tomato plants diluted Phostrogen in the trays,can this be given as a spray ?

    • Mark Downing
      | Reply

      you might stand your pots on damp capillary matting (available from garden centres or the internet), with the other end of the matting in a big bowl of water, to stop your plants from drying out. You just need to top up the reservoir every few days.
      The matting can raise water from a bowl slightly below the level of your bench but probably not all the way up from the floor. The growing medium in the pots has to be in contact with the matting to allow capillary action to work, but normally there is no problem with this.
      One disadvantage I found was that the matting tended to go green with algae after a while, but I suppose you could add something to the water to prevent this (potassium permanganate?)

    • Nick
      | Reply

      Hi Joseph,
      As a foliar spray I would dilute it to half recommended strength and apply it once a week before flowers set. When fruit appears you will need a feed with more potassium, but a feed like Tomorite is for root drench only.

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