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Tomato dropping blossoms - overfertilized?

Hi all,

I have a gardeners delight tomato plant (undetermined cherry) growing in a big pot indoors. I planted it about 3 months ago, it is now good 1.5m high and started growing thruses of blossoms. The blossosm are however are having issues. On one hand, only a few blossoms reach full size, the rest of the bunch seems to be stuck in a premature stage. Whats even worse, the mature blossoms started falling off, despite my efforts to hand polinate them.

I have a grow light helping my plants in these dark winter days and a warm air blower to keep temperature and humidity in check.

Reading up on it and excluding other factors (temperature and humidity) my theory is that my blossom problem is due to overfertilization. I applied a generous amount (i thought it was still within limits) of miracle gro granulated slow release fertilizer (N intensive one) to the mix before potting. Occasionally I also fed the plant with a few sips of miracle gro pour and feed (balanced one), the plant seemed to be enjoying it...

But now I think I need to get rid of some excess N. Any suggestions on how to do it? The problem obviosuly is that I have a full grown plant, I cant go about replacing the soil or anything can I?

Much appreciated








  • sotongeoffsotongeoff Posts: 9,802

    I have one question -why?

    But seriously -this is really an outdoor or greenhouse plant-to grow it indoors during the winter is just against nature-it is just not getting the right conditions-the humidity,light, air flow is all wrong.

    It needs a high potash feed -a tomato feed if you like-but I fear this is never going to come to anything.

    And again-why?

  • I'm no  expert on tomatoes but I was just wondering whether you have done this before of whether this is an experiment. If the latter, then good for you. That's how knowledge develops. If you have done it before, was it different that time?  

  • Busy-LizzieBusy-Lizzie Posts: 23,767

    I think tomatoes need more light than is possible for a home grower to give them at this time of year. They need the sun to fruit.

    Dordogne and Norfolk. Clay in Dordogne, sandy in Norfolk.
  • joslowjoslow Posts: 218

    sutongeoff you are a real killjoy, why are you so obsessed with doing eveything at the right time, people enjoy forcing plants and Andras may well prove you wrong.

  • This is indeed an experiment. It makes no sense what so ever to try and start a tomato in winter, I know. But I have no space to grow stuff anywhere except my lone west facing bay window. And I WANT to grow stuff, no matter the time of year, because this is my hobby. Wen it comes to hobbies, rules and rationality don't apply. On the contrary, breaking rules and paradigms just makes it more fun. imageHence the wacky grow light and heater set-up.

    With my 425W equivalent compact fluorescent bulb I can provide ample lighting even outside daylight hours. Since flowering has started temperature has never went below or above the tolerance of the plant. It has nutrients, it has water... so I'm still hoping this can go somewhere. If only the blossoms behaved well...

    So if my theory is right there is too much N in the soil and thats causing blossom drop. Maybe it's right maybe it's wrong. I will try some things to counter that such as leeching with water (difficult in a pot...) and adding sugar to the soil (I've read it somewhere that the carbon content will have a good effect).

    But if someone has other ideas how to leech or counter N in the soil, please let me know, this is the original purpose of this thread...

    p.s.: Yes it probably costs more than I will ever get out of it, but it is for fun... heck last week even the police showed up knocking at my door 6:30 in the morning, because they thought I was growing weed... in my window... they were quite disappointed to learn that it is only for a couple of tomatoes and salads that my window glows like a supernova. image.


  • figratfigrat Posts: 1,619
    Here's something I got fro googling excess nitrogen in potting soil (rather than potting compost) as that's what the Americans call it.

    "Leaching is a beneficial technique for washing excess salts and fertilizers from the soil of potted plants. When you apply fertilizer repeatedly to potted plants, salts from the fertilizer build up in the soil and can burn plant roots. You can sometimes see a ring of salt on the outside of clay pots or around the top of the soil. The College of Agriculture & Life Sciences at the University of Arizona recommends leaching potted plants every four to six months to prevent salts from accumulating. To leach a potted plant, pour approximately twice the amount of water as the pot can hold on the top of the soil and let it drain completely."

    I admire your experimental quest, but also know people who grow chillies indoors all year round, maybe you could try that?

    Good luck!
  • LeggiLeggi Posts: 489
    An interesting experiment. It could be that the air indoors is too dry which can cause blossom drop (flowers wither and drop off). Give them a daily spray of water and maybe keep a tub of water nearby which you can top up. You could have a problem with pollination but if you regularly tap the flowers that should help. Good luck with your project.
  • Thanks for the tips there! I live in the UK, I think the more likely issue in these parts is excessive humidity then dry air. My window is contantly dripping with water condensating on its cool surface. That is what I try to keep in check with the warm air blower. Oh well I will try leaching and lets see what will happens.

    I will keep you posted, though I dont think results will show very soon.


  • SwissSueSwissSue Posts: 1,447

    Have a look on here, lots of info which might help:


  • WelshonionWelshonion Posts: 3,114

    You appear to be over-feeding this plant.  Do not feed at all until at least one truss or branch of tomatoes is there developing.

    You can tell if the plant is getting too much water if beads of water are appearing along the edges of the plant.  Tomatoes are plants that will grow hydroponically in which case beads of water will indicate they are getting enough!

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