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Thread: Cuke help!?!?

  1. #1
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    Default Cuke help!?!?

    Got some great cukes going in a greenhouse in grow buckets but two of the 4 plants are turning VERY yellow. Tried to post a picture but cant seem to using my phone. Ive been giving them miracle grow tomatoe and cuke food and started calcium and magnesium once a week about a month ago. Thinking they might not have enough nitrogen I went to regular miracle grow last week but no improvement yet. Any advice?? Thanks!!
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    Member Tearbear's Avatar
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    I think cucumbers do best with low nitrogen, I heard a 5-10-10 fertilizer was what they like. Not sure about the yellowing, maybe it gets too hot in your greenhouse?
    "Grin and Bear It"

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    Supporting Member iofthetaiga's Avatar
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    Could be nitrogen deficiency, but could be mosiac virus too. The progressive yellowing from the leaf edge inward looks more like nitrogen deficiency than mosiac virus, but tough to know for sure. If in the same soil, same volume, same nutrients, and treated the same as the unaffected two, I would guess mosiac virus.
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    It looks like MgSO4 deficiency. If the new growth is green or not as bad I am probably correct. Epsom Salt is mobile in the plant, it will move out of older growth into newer growth where it is needed, it is central to the Chlorophyll molecule.
    I use it everytime I water, my cukes look green with very large leaves. lots of cukes too.
    Good luck

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    Default cukes

    here's a pic of how they should look. I assume you grow in pro mix, etc. If you do, use a high K fertilizer, second needed element is N, you must also supplement with equal amounts of CaNO3, MgSO4 is 60 percent of those ratios.
    This should help, it is a common ratio used by production growers.
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    Member Tearbear's Avatar
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    Thanks for the cuke info Mark. I'm afraid my thumb will never be as green as yours.
    "Grin and Bear It"

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    I'll try to keep adding Mg and Ca once a week from the top. I was warned that if I try to add those to my auto watering system/grow bucket water it would make the K drop out and make a mess. Does that make sense? I gravity feed from a 5 gallon bucket, could I just mix all that together in that at once??

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    Your almost right. Ca and P mixed together at once will yield P precipitation, the P cannot be taken up then. You must mix it in two tanks, or by two injectors, or mix one then mix the other to avoid P precipitation. I would plumb two units together after they are mixed, if your doing a bucket or tanks make sure they are the same height, then they will feed at an equal pace.
    I think adding MgSO4 once a week would not be enough.
    Good luck

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    Ok this is very helpful (probably moreso for next year as this year may be too late). The grow buckets feed/water from beneath semi hydroponically, i.e. 2-3" of water beneath the soil, so if I add the Ca into that water at any point the P will drop out correct. So I can mix the MgSO4 in my watering/feeding system but the Ca will have to be watered into the grownix from above?? We are getting all the cukes we can eat (and we eat them daily!!!) from 4 plants, so it's been really good....the plants just look sickly. Thanks for your help!!

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    You can mix your fertilizer and (MgSO4)( Epsom Salt) together at once, in the same tank lets say. You should mix your (CaNO3)( Calcium Nitrate) in another tank. Now they are both mixed and can be plumbed into a single line, any line, any style.

    Both mixtures I mentioned in parenthesis is sold as Cal-Mag in a liquid form, that is probably what you may want to consider for the Ca and MgSO4 that your missing.

    If you are not happy after this, get some pots and use pro mix, buy Flora Nova 7-4-10, use a medium strength, add, 1/2 teaspoon of Cal-Mag, drop your Ph to 6.2, and you should have cucumbers in excess.

    I think you will also find that the fruit actually tastes better when the plants are healthy.

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    The P won't drop out of the fertilizer when the two liquid solutions mix?

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