Ways to use Plants in Soap Recipes
Creative ways to use plants in soap making, including those for scent, exfoliation, decoration, and natural color. Many can be used for both hot process and cold process soap recipes.
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As a gardener, I grow a lot of herbs, flowers, and plants for soap and skincare. There’s something so exciting about using plants that you’ve grown yourself to make lotion, salves, and natural soap! Previously, I’ve taken you through using herbs and flowers in soap but there are many other ways to use plants in cold-process soap making. Special roots that infuse deep color, seeds that add texture, and even plants that have soap-like qualities in themselves. It’s not difficult to infuse handmade soap with plant-based therapy and decoration but you need to know how and when to do it.
Using Plants to Scent Soap Recipes
First of all, let’s talk about scent. I feel that a lot of people expect plants to scent their soap and are disappointed when they don’t. While flower petals can add some scent to the tops of bars, they don’t add much to the soap itself. That’s because the amount of plant material that you use in making soap tends to be quite low. The best way to naturally scent soap with plants is to use essential oil.
What are Essential Oils
Essential oils are concentrated volatile oils extracted from flowers, leaves, bark, and fruit. The usual way that they’re created is by steam distillation or solvent extraction. In steam distillation, a large amount of plant material is put in a pressurized vat and then steamed. As the steam passes through the plant, it picks up its volatile oils. That steam is then directed into a cooling chamber where it becomes water with a layer of oil floating on the surface. The oil is an essential oil, and the water is a hydrosol.
To make a small 15ml bottle of lavender essential oil, you need three pounds of flowers and a home distiller. To make the same amount of rose essential oil, you’ll need 726,000 rose petals. A lot more than you can grow in the average garden! With that amount of plant material, you can understand just how concentrated essential oils are and why it’s crucial not to exceed usage rates in soap recipes. Although completely natural, they contain allergens that can cause skin irritation.
Whole Plants Used in Soap Recipes
Although it’s challenging to make your own essential oil, there are other ways of using plants in soap making. You can use them to add natural color, to add texture and decoration, and to infuse the bars with plant therapy. Fortunately, using whole plants is a lot easier and safer than using essential oils, and you can be a little more creative with how much you use. A pinch of this or a sprinkle of that is possible with dried herbs, flower petals, poppy seeds, and the like.
Plants for Naturally Coloring Soap
You can get almost every shade of the rainbow with plant-based soap colorants. Yellows are easy, and you can use purees of carrot, goldenrod, and calendula flowers, among many others. Alkanet, madder, and gromwell roots create pinks and purples when infused into soaping oil. Woad and indigo powder added at trace create blue.
Ironically, the most difficult plant-based soap color to achieve is green. Spinach or parsley soap, made with powder or puree added at trace, is gorgeous when first made. Unfortunately, if stored in a bright place, they quickly fade to yellow or tan. It’s happened to me many times! You pick up the once vibrant bars to find they’re only green where the sun doesn’t shine.
I have a lot of recipes for naturally coloring soap here on Lovely Greens, including using alkanet (purple), calendula (yellow), annatto (orange), and woad (blue). Find an extensive list of natural soap colorant ideas here.
Plant-Material that Adds Texture
Exfoliating soap isn’t for every day, but it can be beneficial for washing grubby hands or giving your skin a good clean. I use finely ground pumice rock in some of my bars, but you can also use plant material to provide texture and exfoliation. In a couple of my recipes, I show how to use poppy seeds, but you could also use raspberry seeds, oatmeal, sliced loofah, coffee grounds, or chopped dried herbs like rosemary.
When it comes to exfoliants, a little goes a long way. For a one-pound batch, begin with a quarter teaspoon of your ingredient added at trace. That’s often all you need, but if you want more, you could double that amount for the next batch.
Decorative plants used for soap making
Coloring bars is one way to decorate them, but you can also pretty them up with dried flower petals. Just be aware that most will turn brown if you mix them into soap. There are exceptions, like calendula petals, but stick to decoring the tops with dried, never fresh, plant material. If you use fresh, know that it will go moldy and spoil your soap. Also, consider the mess that dried flowers can make in your shower or tub, and add them conservatively. Some of my favorites are red rose petals, cornflower petals, and whole lavender heads, but you can use chamomile and other skin-safe herbs too.
I encourage you to use whatever amount of dried plant material you want to decorate your soap. If you’re making bars to sell, there are rules on how much you can use, but for personal use, it’s more flexible. When decorating loaves of soap, remember to cut from the bottom to the top (upside-down). That way you don’t drag the petals through with your blade. Here’s more information on using dried flowers and herbs in soap.
Using Plant-Infused Oils in Soap Recipes
To achieve vibrant colors in soap, you can infuse one or more of the main soaping oils with roots or seeds. Annatto seeds create stunning soap, and madder is another of my favs. With naturally coloring soap, you add the infused oil either with the main soaping oils or at trace.
There’s another reason to look into plants used for soap making – plant therapy. A lot of us create healing herbal oils to use in making lip balm, creams, or salves, but you can also use them in handmade soap.
I’m more of a fan of reserving herbal oils for leave-on products, but there’s no harm in using them to superfat your batches. That means that you reserve an amount of liquid/melted oil to add at trace, with the hopes of it staying in your bars as oil rather than soap. That amount tends to be around five to seven percent of your recipe, and a lot of folks use melted shea or cocoa butter. You could instead superfat with liquid oil, such as olive oil, infused with dried herbs like comfrey, chamomile, and calendula.
Lastly, there are plants out there that already naturally contain saponin, a soap-like substance. Some are wild plants, but others could even be growing in your garden right now. I introduce soapwort, English ivy, horse chestnuts, and several others in my piece on making simple soap from plants. It’s amazing to see bubbles form after just boiling the leaves in water!
I have a indigenous saponin rich plant here from South Africa. I would like to make soap bars with it but not for its saponin qualities but for it’s spiritual application so it is important to have the actual plant matter in the bar of soap…. How can I do this? could I for instance stir some of the dried plant material through the soap before pouring it? So as the second last step?
Hi Carla, and it depends on the plant. You need to check that it’s skin-safe first. Then you can either make a tea of it (could release the saponins) to use in the lye solution and/or add it during the soapmaking process. Please be aware that it will likely not have any effect on the lather or cleansing of the soap bar itself.