Growing Your Own Soapnut Tree

The soap nut tree Sapindus Mukorossi aka Indian Soapberry is a very large tree that produces prodigious amounts of a soaponifying nut that you can use as a greywater safe laundry detergent, dish and hand soap. Mrs. Homegrown wants to rip out my beloved Mission Fig tree to plant the one that Craig at Winnetka Farms gave us last year. I’m going to chain myself to the fig.

That being said, I wish we had more room to plant our soapnut tree. Sapindus Mukorossi requires a fertile soil and a frost free climate. It’s a tall tree that can take as long as ten years to begin fruiting. A friend of mine has one growing in Altadena.

Sapindus Mukorossi needs lots of water. Craig has pointed out the perfect permacultural pairing for our dry climate–use the greywater from your washing machine to water your soap nut tree.

It can be a bit tough to get the seeds to germinate. Here’s some instructions on how to grow Sapindus Mukorossi from seed.

If you’re in LA you can buy a tree from the folks at Winnetka Farms.

I vote for Sapindus Mukorossi as LA’s next street tree . . .

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16 Comments

  1. I vote for the fig.
    How are the roots on the soap nut tree? Will they get into the pipes or lift up foundations? Having huge trees may not make for friendly neighbors. Maybe it would be better to just buy a bag of soap nuts. They last a long time and are a lot less problem then huge trees. I say this from personal experience.

    • I don’t know why it posted as anonymous???

      When trees of any size are improperly planted they can be a problem. However with some research and understanding of the trees growing requirements everyone can plant a tree if they need to or want to. This tree when planted to make the most of it will give shade where needed as well, it will eventually produce soap for cleaning. What a great use of grey water.

  2. This tree looks like a candidate for a “neighborhood” tree that could be planted in a neutral place where everyone could use the bounty it provides. After all, who could use that many soap nuts. That is a huge tree! Of course, if someone had a large enough property, this could be an income…in ten years.

    I always thought soap nuts were a joke like a snipe hunt or were the figment of a wishful imagination.

  3. Saponins are OK in irrigation water, if you can find a way to break them down before they reach soil you would want worms in, but the idea of tons of soapberries in storm drains makes me a little uncomfortable.

    Not that LA streets are clean to begin with, but using this as a street tree could poison a lot of fish each rainy season, and could also exacerbate problems with petrochemicals washing off of pavement (like an organic, natural Corexit).

    • If soap nuts will adversely affect worms, would that mean that the tree should not be near a garden? If so, it seems this might not be a good tree to plant on a city lot that also grows food.

    • My understanding is that saponins decompose quickly, but are acutely (i.e., in the short term) toxic to fish and invertebrates. Some soap nuts rotting on the surface of the soil don’t seem likely to cause trouble, but flooding a whole garden with an intentionally concentrated solution of saponins might cause a dieoff.

      A lot of permaculture systems direct greywater into an artificial wetland, which gradually drains into more-typical garden soil. Saponins would kill mosquito larvae in the “surge” part of a system like that, but I’m guessing they’d have enough time to break down before reaching earthworms.

    • Soap berries in storm drains is something I hadn’t thought about. Interesting! No, that wouldn’t be nice in quantity.

      But unless things change a lot suddenly, I don’t think its ever going to be a problem, since there may only be three soap nut trees in all of LA (ours and our friends’), and none of them are fruiting yet! They’re not sold anywhere. If any of us get fruit we will be greedily picking off every one of them.

      There’s a native US soapberry tee, Sapindus saponaria. I’ve never met one–its range is something like from Arizona to Louisiana. I don’t know if it’s often planted in urban settings, but I wonder if fruit fall is a concern to folks in those parts.

  4. I vote to keep the fig tree, too. Perhaps you could trade some figs for soap nuts, from someone with more space for large trees.

    I also like Practical Parsimony’s idea of a neighborhood tree.

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  6. I love planting any trees,but esp those that yield an addition benefit for our tiny planet. I live outside of Atlanta, and we are prone to a frost now and again. Really wish I could plant this. Thanks for all the great info.

    • Oh yes, Soapwort! We wrote about that in Making It. I’ve purchased dry soapwort and used it, but it doesn’t grow around here, sadly. If it did, I’d be out collecting it by the armload. ;)

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