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plantmomzone10asunset16

Redwood needles as mulch for tomatoes, squash, and vegetables?

I have access to a large quantity of redwood needles...is it okay to use the needles from redwood trees as mulch in my vegetable garden? and for mulch under fruit trees? Or is it too acidic?

Comments (10)

  • plantmomzone10asunset16
    Original Author
    3 years ago

    Thank for that insight! Very helpful!

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    3 years ago

    Agreed. They are fine as mulch. But be aware that pine needles break down more slowly than other organics. So while mulch is often dug in at the end of the season as a beneficial amendment, it is less useful to do that with pine needles.

    plantmomzone10asunset16 thanked daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
  • iochroma
    3 years ago

    I disagree - redwood duff contains allelopathic compounds which inhibit the growth of other plants. Pine needles are less inhibiting.

    Search for papers on 'Redwood and allelopathic' topics if you want the science.

  • gardengal48 (PNW Z8/9)
    3 years ago

    Most trees have some allelopathic properties. But studies done on the allelopathy of various tree species rates Sequoias as 'slight', whereas most Pinus species are rated at 'moderate'.

    Not enough of an issue to prevent their usage, IMO.

  • tsugajunkie z5 SE WI ♱
    3 years ago

    ...and the allelopathy of conifers is more in regard to seed germination rather than affecting growing plants. After all, pine straw is a great mulch.

    tj

  • iochroma
    3 years ago

    Have you actually tried redwood needles as a general multch in the vegetable garden? I bet not. My neighbor did, against my advice. He learned.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    3 years ago

    https://ui.adsabs.harvard.edu/abs/2019AGUFMED41B1025L/abstract

    Suggests not. This was mainly looking for allelopathic effects on grasses, but they also tested radish germination.

  • gardengal48 (PNW Z8/9)
    3 years ago

    Important to take the last statement of that study's abstract under consideration:"Alternatively, there is a possibility that the allelochemicals of the tested tree species are not emitted through their leaves but more so through their roots." As is very often the case with any allelopathic genera.

  • l pinkmountain
    3 years ago
    last modified: 3 years ago

    The devil is in the details. How much will you use? How fresh? Under what other soil, moisture and light circumstances? That also influences soil acidity, because some soils are naturally prone to acidity and others not. I am lucky to live in an area with limestone bedrock, so soil acidity only exists under very specific situations, on the flip side, granite bedrock tends to create acidic soil conditions. Conifer wood and needle acidity and allelopathic properties dissipates over time, so fresh is different than aged but that's the same with any type of plant material as mulch . . . What is your soil's natural fertility? Also, if you want to keep down weeds, then suppressing seed germination is a good thing . . . Also, mulch affects different zones of the soil differently, and therefore different parts of the plant. For example, a fresh mulch that is going through a lot of hot decomposition might burn sensitive seedlings early on if you casually toss it over them, but be fine around a tree and will not immediately interfere with what might be going on deeper into the root zone . . .