Fertilzer for blueberries and raspberries

newslangJune 8, 2007

I've been looking around online and am finding some conflicting reports on the best fertilizers to use for these plants. Anybody have suggestions for the N:P:K ratio to use for raspberries and/or blueberries? Also, is it too late in the season to fertilize if I live in MA?

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Embothrium(USDA 8 Sunset 5 WA)

Would be expected that different formulations would be used for the two types. Regarding fertilizing generally, this is affected by existing nutrient content of soil (and irrigation water, truth be told). You really should sample soil and have it tested at least once before fertilizing.

    Bookmark   June 8, 2007 at 5:47PM
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Yes I know the ideal formulations for the two are different, I should've made that more clear. I think the most I'd be willing to invest for testing would be pH testing. I'm just doing this for fun and don't have a lot of money to spend. To help people in making suggestions I should say that I used canadian peat moss (sphagnum) for soil, completely wrong I know but it's been a few weeks and both plants are growing. Estimates of the best fertilizer formulations are welcome.

    Bookmark   June 8, 2007 at 7:24PM
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I like cottonseed meal for blueberries. Not expensive (if bought in a large bag as it's sold for feed in feed and seed stores), organic and thus slow release, and acidic when breaking down.

    Bookmark   June 8, 2007 at 9:26PM
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I have always heard to use some 10-10-10 formula.

One bad experience: coffee grounds. I have a big empty spot in a part of my raspberry bed where I dumped my coffee grounds all last year. Sadly, the new canes this year didn't seem to appreciate the good intentions, heh.

Another bad experience: the same kelp foliar spray that my tomatoes love seemed to wilt my raspberries and blackberries. They may need a lower concentration. However, now I just don't bother trying to foliar feed them.

    Bookmark   June 9, 2007 at 7:57AM
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There is no "ideal" NPK formulation for blueberries and raspberries, but you are certainly correct that the types of fertilizers for these two berries are different.

Raspberries will accept any ordinary balanced fertilizer, such as 10-10-10 in small amounts. But mulch around the plants is more important than fertilizer to growing healthy raspberries. Very high nitrogen fertilizers, such as those used on lawn grasses with an N number in the high 20's or low 30's should be avoided. Fertilizers appled in liquid form, such as Miracle Grow, are also fine, but calibrate your fertilization to the appearance of the plants. If they are dark green, healthy and growing, just put on more mulch.

You should never use any ordinary 3-number nitrate-based fertilizer on blueberries, although your use of peat moss in the soil mix was completely correct for this plant. If you want to use a high-nitrogen fertilizer, it must be an acidic fertilizer such as ammonium sulphate. That is what I use around my plants. Miracid liquid fertilizer is also good, as are Hollytone, cottonseed meal, and coffee grounds if you don't want so much concentrated nitrogen. But the application of an acidifier such as iron sulphate is often more important to blueberries than fertilizer. Iron sulphate supplies a good amount of iron as well as acidifying the soil.

I don't do soil tests either, but determine the fertilizer needs of my plants based on the vigor and appearance of their growth. But there is no single, ideal formula for berries.

Don Yellman, Great Falls, VA

    Bookmark   June 9, 2007 at 8:36AM
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franktank232(z5 WI)

I bought the miracle grow that comes in plastic packs for acid loving plants. It green. My blueberries seem to love it, they have really taken off lately. They were planted in 100% peat and i added some woodchips also.

    Bookmark   June 9, 2007 at 9:56AM
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Thanks for the all the advice so far. Will mulch signicantly reduce the needed watering frequency? I have been watering daily except when it rains.

And do blueberries like mulch also?

    Bookmark   June 9, 2007 at 4:24PM
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Blueberries need mulch probably even moreso than raspberries. Blueberry roots are very shallow, raspberries go deeper.

The mulch will help retain water, an unless you are in the 100 degree windy desert you probably don't need to water more than once or twice a week once the plants are established and mulched.

    Bookmark   June 9, 2007 at 4:42PM
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