A quick surf around the tomato websites on the internet may lead people to believe:

  1. Tomato plants love lots of water
  2. Tomato plants love the rain

In some ways these two statements are both related and partly true.

Too Much Water
The problem is when the novice tomato grower gets his or her plants home from the garden centre and puts them outside in the rain after watering generously. The result is a drowned plant that is sitting in a pot of sodden, air-less mud.

Of course, tomato plants need moisture around their roots, to dissolve the nutrients in the soil, in order to feed.

When they are growing leaves, they need plenty of moisture in order to replace the water that evaporates from their leaves.

When they are fruiting they need even more water to help swell the fruit.

Older Plants Need More Water
Notice that more water is needed as plants become more mature but whatever stage a plant is at, there has to be a balance of moisture and air in the soil for a plant to grow well and keep healthy.

Over-watering when fruit is growing may cause nutrients to be diluted to the point where tomatoes can become watery in taste.

Rain
Rain water, as we discovered last week is usually on the acid side of the pH scale, and is great for tomato plants – they like soil and water with a pH just below 7.0.

The other great thing about rain water is that it doesn’t contain chlorine or fluoride so that’s an added bonus!

However, wet leaves will always lead to disease if they are wet long enough, so the idea is to keep leaves dry most of the time and roots moist all of the time, but allow wet soil to dry-out a bit before watering again to get the air back in.

So I guess that tomato plants do like water and rain after all – when their age and growing situation is taken into account.

 

10 Responses

  1. Julie Armour
    | Reply

    I have a terrible problem with leaf spot septoria on my tomatoes even though I follow all of the recommendations to minimize this disease. I was wondering if I covered the plant overhead with plastic to prevent rain from getting the plants wet, would this help?

    • Nick
      | Reply

      Hi Julie, keeping the leaves dry will help prevent leaf spot. Also, have plenty of space and air flow between plants.

  2. joseph james
    | Reply

    ,I used to water into trays 3″ deep and kept topping up every time the level dropped to 1″ until I read your advice on overwatering. 2 of my plants had looked limp and I decided to empty the trays and stand the plants in them for a while and was amazed at how much water drained back into the empty trays.The 2 plants are now fully recovered and I’m more careful with my watering. Thanks.

    • Nick
      | Reply

      Hi Joseph,
      I’m pleased that you’ve sorted the problem.
      Cheers,
      Nick

  3. Bob Iles
    | Reply

    Hi Nick, I read Rhys’s comments with interest, I really can’t believe that anyone now would want to grow toms in the ground, no matter how much effort you put into soil preparation and feeding etc. it is still now so easy and reasonably cheap to use growbags or large pots and you don’t have anywhere near the risk of disease or failure. This season I bought six of the growbag pots that you reccomended, they are absoluteley brilliant, you water into the trough and feed into the pot, the results are amazing. I have trialled six of these against six of my normal plants, which are grown in eight inch bottomless pots. All twelve are sunk into Arthur Bowers giant tomorite growbags. While my normal pot grown plants are looking and fruiting really well, I have to say that the plants in the growbag pots are much better still. I have loads and loads of lovely trusses but now need some serious sunshine to ripen the little devils.

    • Rhys Jaggar
      | Reply

      Bob

      I’m growing 10 plants in 10 – 12 inch pots and one in a Grobag. All are doing well.

      I was trying the rest as an experiment as we had no more large pots!

      I have grown plants in Growbags previously and I don’t doubt that you are having success.

      One thing you learn in life is that those who took 30 years to develop expertise can’t pass on their expertise just by people following pat instructions. You learn in life by trying things out and seeing what happens. Not on all your plants, but on some.

  4. Rhys Jaggar
    | Reply

    Exposing tomatoes to the rain by growing them in the soil:

    1. Grand Marmande really don’t do well – my plant produced a great first truss of huge tomatoes, but they slowly rotted in early July and the plant gave up the ghost last week. I won’t be growing it in the ground next year!
    2. Shirley’s seem to do OK: I have four plants in the ground this year and they both grow and fruit well. Fruit are now set on a fourth truss on two of the plants and there’s little if any sign of stress or rotting.
    3. Milla (a strain touted as being good to grow outdoors and also resistant to late blight): this has done brilliantly in the ground for about 6 weeks but has just recently started to show signs of susceptibility to the rain: the plant has set some fruit and lots of flowers now coming, but the mainstem and a few side shoots are looking a bit unhealthy. I think this one should do OK, but maybe has intermediate susceptibility to the rain. It probably should be kept under wraps if at all possible during rain.

  5. Buster
    | Reply

    Hi Nick. How important is the soil composition to get air into the roots.

    I’m trying a half mix of loam & standard compost this year.

    b

    • Nick
      | Reply

      Hi Buster,
      Most soil compositions will be OK as long as they’re not too fine, it’s the drainage that’s important. I find that seed compost can be too fine, even for seeds/seedlings and if there is no drainage, you can end up with mud.
      Regards,
      Nick

      • Buster
        | Reply

        Nick. Most of my varieties are doing ok if a little slow pollinating.
        The loam/compost seems to drain well but the surface does pan & harden more. At the moment it’s much better watering than the dried out total compost of previous years.
        Thanks for your information.
        B

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