9 Natural Soap Plants that Make Lye-free Liquid Soap

An introduction to plants that can be used as soap without having to use lye. Includes common plants such as English ivy and soap nuts but others that can be wild harvested and ways to transform natural soap plants into sudsy cleansers

Years ago, I taught myself how to make handmade soap, and ever since have shared ways that you can make it too. I focus on making soap in the traditional sense, from fats and alkali and my favorite method is cold process soap making. However, I often receive questions on ways to make soap without having to use lye. There are a few ways to make soap without handling it, but inevitably, all true soap is made with lye. We don’t know how long soap has been around for though and in the past, people used natural soap plants to make a soap-like substance.

Saponin-rich plants only need light processing in water, and sometimes they don’t even need that. After agitating them, a liquid soap substance is released that gently cleanses skin, hair, fabric, and even home surfaces. It’s well worth learning about the fascinating properties and how to use saponin-rich plants and I’ve featured nine of the best soap plants further below. Some include videos showing the plant in action and I highly encourage you to have a try too!

Using Natural Soap Plants to Create Soap

Cultures around the world have used simple plants to clean, and some of us still do. I sometimes use soap nuts for washing clothes, and if you’ve tried them too, you’ve had experience using a saponin. Just like soap, saponin is a surfactant and pulls oil and grime from surfaces. It can also create the bubbles that we associate with soap. Horse chestnut is another commonly used soap plant rich in saponins, as is soapwort.

Saponins are a natural plant compound that can dissolve in water, and latch itself to oils. Then the saponin, along with the oil, is washed away by water. We too can use saponins to cleanse our skin, hair, and home and this list of nine of the best soap plants will help you on your way. No matter where you are in the world, there’s bound to be a saponin-rich plant available, whether it’s growing in the garden or a native plant that’s been used for thousands of years.

The Best Soap Plants for Homemade Lye-free Soap

The most well-known saponin-rich plant is soapwort, native to Europe but now found all around the world. The whole plant is rich in saponins, but it’s most concentrated in the roots. Other soap plants are very similar and if you decide to try any of them out for yourself, make sure that you don’t introduce the soap into open water sources such as lakes and streams. Saponins are poisonous to fish and other marine life. Also, please do not eat any of these plants as some are poisonous if taken internally.

1. Soapwort

Soapwort Saponaria officinalis (whole plant, especially the roots) is both a wild and cultivated plant from Europe. It’s rich in saponins from its scented flowers to its stems and leaves. Its roots are exceptionally high in saponin content and can be dried and used throughout the year. Modern conservators still use soapwort to clean delicate fabrics such as antique tapestries.

There are a couple of ways to use soapwort too. You can use the entire plant to scour pans and surfaces or make a green-ish infusion by simmering a cup of fresh, chopped plant parts (or half that amount dried) with two cups of water. Cool, strain, and use in cleaning hair, skin, and for household cleaning purposes. Soapwort makes a great dish detergent! I include a recipe for using soapwort to make a gentle skin and cleanser cleaner in my book, A Woman’s Garden.

2. English Ivy

English ivy Hedera helix (leaves) Finely chop about sixty of the leaves and boil them for five minutes in 4 ½ cups of water. Next, take it off the heat and allow it to cool to hand-hot. Squeeze the leaves and agitate the water to disperse the saponins. Strain the liquid and use it in laundry and in cleaning home surfaces. I’ve used it as a good floor cleaner and can recommend it for that use. You can also use a cup at a time to do laundry and store any excess in the fridge for up to a week.

3. Horse Chestnuts

Probably the most common soap plant, the horse chestnut Aesculus hippocastanum is one that many will know as conkers. In Europe, there’s a custom of children playing with the nuts in autumn but we can use the same inedible nuts to make soap. They’re particularly popular for laundry soap and all you need to do is harvest the nuts in autumn, grind up the meat, and infuse in warm water. a 1:2 ratio of pulverized nut and warm water by volume is perfect and in about half an hour you’ll have a milky liquid that you can use to clean your clothes. Use 1/3 a cup per load and keep any extra liquid refrigerated for up to a week. For the long term, harvest, pulverize, dry the nuts and make a little horse chestnut laundry detergent at a time.

4. Soap Nuts

Soap nuts are the most commercially well-known of the soap plants. These saponin-rich nuts come from the soapnut or soapberry tree Sapindus Mukorossi. Native to warm-temperate and tropical places, especially India, this group of up to a dozen different species of shrubby trees produces saponin-filled berries. They’re then dried and resemble brown nuts. You can use them to make liquid detergent, but it’s easier to put them in a small cloth bag and then in with your laundry. Soap nuts are readily available to purchase.

5. Clematis

That’s right, the beautiful climbing plant that you have growing in the garden can be a natural soap plant. It’s not one that I’ve used yet though but from what I gather, you collect both the leaves and flowers, chop, and soak in warm water. One part plant material to two parts warm water. Use as you would warm soapy water on floors and surfaces.

6. Buffaloberry

The berries of the buffaloberry Shepherdia argentea shrub were once collected by Native Americans to make a type of foamy dessert and medicinal teas. The shrubs grow in the western and north-western USA and Canada and the red berries (sometimes yellow) were only ever eaten in small amounts. Buffaloberry, like most saponin-rich plants, can give you an upset stomach. They make good natural soap though and if you can harvest any sustainably, you can mash the fresh berries together on their own or with water to make a natural cleanser. There’s a video showing it in use just above.

7. California Soaproot

Some soap plants grow in very specific regions and the California soaproot Chlorogalum pomeridianum is one of them. Also called the wavyleaf soap plant or amole, It’s a wild, low-growing plant native to California and Oregon in the United States with long blue-green leaves that die back in winter. It also has a tall flower stalk that can emerge after the plant is mature, at five to ten years old. The part high in saponins is a fist-sized bulb with a fibrous brown exterior and a white interior. The crushed bulb interior, or its juices, creates a soap-like lather when added to water and agitated. Another similar species, the Narrow soap leaf plant Chlorogalum angustifolium was also used as soap by Native Americans.

8. Soapbush Tree

There are soap plants on practically every continent and the next one comes from down under. The soapbush tree Alphitonia excelsa is a native Australian tree that has leaves rich in saponins. The video above shows how easy it is to extract the foamy soap-like substance by just using fresh leaves and cold water. Please don’t use saponin plants so close to water sources though since adding it to water has the potential to kill fish. That goes for all soap plants, not just the leaves of the soapbush tree.

9. Soapweed Yucca

Soapweed yucca Yucca glauca is a wild soap plant native to the prairies and great plains of North America. This plant has high amounts of saponin in its roots, which are crushed and either soaked or simmered in water. The bubbly and foamy liquid has traditionally been used as a natural shampoo and cleanser and you could do the same too. When harvesting plants for their roots it can often kill them though so if you’d like to use soap plants sustainably, harvest those that are invasive or that you can use aerial parts only.

How to Extract Saponins from Plants

Because saponins dissolve in water, it’s relatively easy to extract them from plants. All you need to do is soak or boil the plant material, fresh or dried, in water. The amount of plant material to water isn’t exact, and you base it on how much saponin the plant has. With soap nuts, you tend to use five ‘nuts’ (actually fruit) for a load of laundry, but you can reuse them too. They still contain saponin even after being used a couple of times.

My soapnut sachet is usually pretty full since I don’t take them out often and just add a new nut for each load. Warm water dissolves the saponins in the soap nuts and also washes the dirt and saponins away from your clothes. Some plants are higher or lower in saponins, so the amount you use for each type will be different.

I’m using the example of soap nuts because a lot of people use them as they’ve become more readily available in health food shops and online. They’re a fruit that grows on a group of shrubby trees in the soapberry family, but when dried, look a lot like nuts. These Sapindus species shrubs grow in tropical and sub-tropical places like India, so they’re not something that everyone can grow. Fortunately, there are saponin-rich plants that will thrive in temperate climates too.

More Natural Soap Ideas

Although these amazing saponin-rich plants are great at cleansing, even the best soap plants can’t take the place of real soap. If you’d like to try your hand at making homemade soap with natural ingredients, try these easy and eco-friendly recipes that you’ll find here on Lovely Greens. You can also learn more about the seven ways to make handmade soap.

• No Lye Soap Recipe (melt-and-pour)
• Eco-friendly Soap Recipe
• Simple Hot Process Soap Recipe
• 3 Easy Cold Process Soap Recipes