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Using Potato Water in the Garden to Nourish Plants with Potato Starch

Plants need nourishment to perform in the best way.  Flowers and vegetables love potato starch and using potato water in the garden is a good way to give it to them. 

Potato Starch

To add starch in a “green way”, save the water you boil your potatoes in.   Starchy water will spur the release of plant nutrients in the soil so it makes a great addition.

Water that has been used to boil vegetables contains minerals and vitamins that naturally leak from the plant cells while the vegetables cook.

Note: Don’t use salted potato water since this can harm plants.  Use unsalted potato water, let it cool for a while, and then use it to water your household plants.  

This works because starchy water spurs the release of nutrients in the soil. Recycled and unsalted pasta water also works in a similar way.

Recycle your boiled potato water and use the potato starch on your plants.

Don’t substitute potato water for plant food. Potato starch is just one form of nourishment and plants need many others.  Just use the potato water in addition to any plant food you may already use.

If you save any potato water to use over a period of days, be sure to shake it to stir up the nutrients before giving it to your plants. Just add it to your watering can and water as you normally do.  Fertilize on another day.Add starchy potato water to a watering canThe water from boiled potatoes can be used on both outdoor plants, such as vegetables, and indoor plants.

Potato water (and other vegetable water) is also great to use on the compost pile.  And don’t forget to add the potato skins there too!

Plants are not the only thing that likes starchy potato water.  You can use it around the house too.

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Don't throw that potato water away when you are done cooking the spuds. Head out to the garden with it! Find out how to use potato water in the garden at The Gardening Cook. 🥔🥔 Click To Tweet

Using salted potato water in the garden

The use of unsalted potato water outlined above is beneficial to plants but salted water can harm them. How can we put salted potato water to use in the garden?

Both salt and boiling water are great weed killers. When you cook potatoes in salted water, use the drained right away on undesirable weeds in your garden paths. This type of weed killer works best with broad leaf weeds.

Be sure to keep this water away from plants!

Other uses for potato water.Potatoes boiling in water

  • Use it as a base for gravy (you won’t need to add as many thickeners!)
  • Save the water and use it in making mashed potatoes. It will lessen the amount of cream needed to make them lighter.
  • Add a bit of salt and pepper to it and drink it as an almost 0 calorie food.
  • Add potato water to bread mixes to add texture and a bit of extra flavor.
  • Pour over dehydrated vegetables to hydrate them.
  • Pour potato over dry dog food. They will LOVE it!

How long will potato water last?

If you plan to use potato water in other food recipes, it will keep well in the fridge for about a week.

For longer periods, freeze the potato water to use later.

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Would you like a reminder of this post for potato water uses? Just pin this image to one of your household tips boards on Pinterest so that you can easily find it later.

Using potato water in the garden

Admin note:  This post first appeared on the blog in June of 2014. I have updated the post to add new images and additional tips for using potato water in the garden and in recipes.

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Saturday 10th of December 2022

I love your information thank you so much I am learning how to have an organic garden and use household products for cleaning my home.God bless you and Merry Christmas!

Carol Speake

Sunday 11th of December 2022

Merry Christmas to you, too, Tina. I'm glad you enjoy my articles.


Monday 28th of November 2022

Any good idea as to how to get rid of moles, gophers take are taking over our front/back yards.

Carol Speake

Monday 28th of November 2022

Hi Camille, My husband and I have a similar problem and have not found a solution. Perhaps a reader will chime in with suggestions.


Saturday 30th of April 2022

I do alot of blanching for dehydrating. Great to know I can reuse all the water!! I always feel ad du ping the water down the drain. I can omit salt in my cooking to use even more water in the garden. Thanks so much for sharing this!!! 😉

Sharon Phillips

Monday 7th of June 2021

Absolutely love this idea. My partner 35 had got his own allotment and through that I'm leaning more and more how we can be more planet friendly so this is a fab idea.


Monday 25th of May 2020

I told my husband about putting my potato water on the plants he said he didn’t think it was a good idea he said only put on one I don’t want to lose all the vegetables

Carol Speake

Wednesday 27th of May 2020

The main thing that you need to be careful with on the water is that it is cooled, (certainly not boiling hot) and Un-salted. both will kill tomatoes. But cooled water that has not been salted is fine and adds extra nutrients back to the soil.

Since most potato water is salted, this should not be used. Salt is a natural weed killer and will also damage tomato plants.

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