Broccoli leaves turning purple

rangerbubba(8)February 20, 2009

I have a few small Broccoli di cicco transplants that I raised from seed that I planted in my raised bed about 2 weeks ago. Yesterday I noticed that a few of the lower leaves were turning purple. The newer growth looks fine, although the plants are not growing very quickly. My raised beds are filled with a pre-made mix that had lots of organic matter and expanded shale. Drainage does not appear to be an issue. I haven't tested the ph of the bed.

I've heard with tomatoes that purple on the leaves can be a phosphorous deficiency. Could this be the same thing?

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Yes, that's exactly what it is, a nutritional deficiency. Hard to say exactly what nutrients, since the deficiency symptoms of most are pretty similar.

Throw some good, all-purpose fertilizer, preferably one that also has micronutrients, on them, and they should be fine.

Some of the purple tinge might just be acclimation to the outside weather as well. But, can't hurt to fertilize (well, as long as you don't overdose them).

    Bookmark   February 20, 2009 at 7:33AM
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Many plants leaves and stems will deepen in color when temperatures drop. If you did not harden off your transplants before setting them out or if your outside temps have dropped to near freezing it may be a natural reaction.

Here is a link that might be useful:

    Bookmark   February 20, 2009 at 8:56AM
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They were hardened off for 2 weeks before I planted them, sometimes in cooler temps than what we're having now. My instinct last night was to treat them with some 5-3-3 fish/ seaweed/ molasses emulsion diluted 5T per gallon. Hopefully that will help. I've heard broccoli is a nutrient hog and there still a lot of rough matter in the mix they're planted in. I guess I'll just complete my decent into gardening madness and spring for the electronic soil tester! :) Thanks, all!

    Bookmark   February 20, 2009 at 11:34AM
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also becareful you dident get an ornamental type of it.

    Bookmark   February 20, 2009 at 11:45AM
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bella_trix(z6b SE PA)

Could you post a picture of them? I've raised De Cicco for the past two years and I vaguely remember that they took on a purplish cast in the garden. I think it may just be the variety. Unfortuately, I don't have access to my photos right now; I'll take a look tonight.

If you can put up a photo, it might be easier to tell if it is a nutritional problem or just natural coloring


    Bookmark   February 20, 2009 at 12:42PM
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Here are the pictures:

These are 3 different plants. I put the white paper behind them so they would show up a little better against the mulch.

I got an electronic soil tester. & tested the bed today. the ph throughout the bed is 7, so that's good. The fertility rated at the high end of "too little." (Its a needle gauge). I gave the broccoli & other plants in the bed another douse of the 5-3-3 fish & seaweed mix, which is the most balanced stuff I have right now. I guess my next step is to get the test tube kit so I can see exactly where I'm lacking on the NPK. What makes me nervous is that I'm getting ready to plant my tomatoes in the same bed in a week or two.
I suspect the rough stuff in the bed might be eating up a lot of nitrogen. Would it be best to mix a few bags of really finished compost in where I'm going to plant, or to apply a fertilizer to what I've already got? I'm trying to do all this organically.
Thanks to everyone for their prompt responses!!! I've been lurking on the forums for a while, and have been able to answer most of my questions with a search. Hopefully this will help others with the same problem.

Here is a link that might be useful: Broccoli plants

    Bookmark   February 21, 2009 at 4:13PM
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engineeredgarden(7, nw Alabama)

Boron.....a deficiency of boron makes the leaves of leafy vegetables turn purple.


    Bookmark   February 21, 2009 at 4:25PM
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bella_trix(z6b SE PA)

I took another look at my De Cicco seedlings and they were not the ones that turned purple (it was the Mammoth cabbage). Your pictures do not look good (well, the plants in the pictures), although the new leaves look OK, so that's encouraging.

I'd be suspicious about the wood mulch. I've heard it is not recommended in the garden (except paths), particularly not right against the plants. At the least, I'd pull the wood mulch back 6-12 inches from the plant or consider getting rid of it entirely and replacing with compost. Do you know anything about the source of the wood chips? I'd hate to think that you have black walnut wood chips mixed it. It definitely inhibits plant growth, but I don't know if they turn purple first.

Hope you find the solution,

    Bookmark   February 21, 2009 at 4:42PM
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The mulch is cedar. I'll go ahead and pulln it away from the plants some.

How exactly would one add boron to their soil?

    Bookmark   February 21, 2009 at 5:05PM
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Beware of boron toxicity! Test your soil first before adding boron. Phosphorous availability is often limited in cold soils. It isn't that there isn't any there but that the processes that make it available to your plants is in low gear when soils are cold. Putting mulch around the plants will exascerbate the problem by insulating the soil thereby keeping it cooler, longer. One method to avoid the problem when planting in cold soils is to band a high-P fertilizer/nutrient source within a couple of inches of the transplant and about an inch below it's depth. A Urea-N source N fertilizer with the P fertilizer has a not well understood synergistic effect in helping P uptake from the band. Also, if there is anything you can do to modify the environment to cause and maintain soil warming prior to and post planting, such as laying black mulch in intimate contact with the soil, cold soil P problems may be aleviated.

    Bookmark   February 21, 2009 at 5:33PM
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macheske(6/7 NorthernVA)

They just look cold to me. The broccolini I planted outside last year looked like that for a few weeks and then went green when the ground warmed up a little.

    Bookmark   February 21, 2009 at 6:17PM
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well after looking at the frozen soil here today,,,your plants look pretty good...look to me also like they are just cold, i grew geat broc through cardboard with soft wood shavings covering, right up to the stems, it is a good thought that this mulch might keep the soil from warming as quick as bare ground. broc on

    Bookmark   February 21, 2009 at 9:20PM
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"How exactly would one add boron to their soil?" Liquid seaweed. It has a lot of micronutrients including boron. If your plants are still purple after you warm them up, you might want to try some seaweed. It's not only good for boron but for stressed plants in general. It's like a natural SuperThrive.

    Bookmark   February 21, 2009 at 9:45PM
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