Guide to Using Herbs and Flowers in Soap Recipes

Tips on which herbs and flowers are best in handmade soap & ways to use fresh and dried plant material in your recipes.

I use a lot of homegrown herbs and flowers in soap, lotions, balms, and other skincare recipes. There’s a reason for using each plant though, and choosing the right ones for the correct purpose is part of making good soap. In natural soap making, herbs and flowers are mainly used to add texture, color, and decoration. Dried rose petals decorating the tops of your bars can smell rosy and a sprinkle of poppy seeds can add exfoliation. Some flowers can tint the entire batch of soap a natural color, or add flecks of visual interest, as in the case with finely ground peppermint or lemon balm.

There are other questions to ask yourself about using plants in soapmaking. Is it skin-safe? Does it have potential therapeutic benefits? Can we use supermarket flowers? This piece helps to answer questions on how and when to use herbs and flowers in your soap recipes. There are also links to floral and herb-based soap recipes peppered throughout the text.

Best Herbs for Handmade Soap

You can use ordinary culinary herbs to make handmade soap. Dried rosemary can create dark speckles, pureed spinach or parsley makes a vibrant green soap (at least initially), and dried peppermint straight out of a teabag can be sprinkled on the tops of bars as a decoration. Though they won’t leave too much of a scent, whole herbs create interesting colors and effects in your soap batches. Some of the best dried herbs that you can use include:

• Lemon balm
• Parsley
• Peppermint
• Rosemary
• Sage
• Thyme

The Best Flowers for Soap Making

Using flower petals in soap can be a little tricky. Most of them turn brown if you try to stir them into your soap batter. Others might not be suitable for skincare recipes so please research a plant and its flower before using it. If a flower is edible, then it’s a safe bet for using in making handmade soap. If it is not, or is known to be toxic if eaten, then don’t use it in skincare.

When using flower petals, you have the option to use them as a puree to tint your soap, as in the case of goldenrod. You can also sprinkle dried flowers onto the tops of your soap and in some cases, such as in calendula, you can stir petals whole into the batter. Orange calendula flower petals also infuse well into liquid oils which is how I achieved the buttery yellow color of the below soap. Very few flower petals will keep their vibrant color in soap but calendula is one of them. Blue cornflowers are another, although they’ll lose their color if mixed into the soap batter.

Be aware though, that using fresh or dried flowers and herbs in or to decorate soap can be problematic in humid climates. The moisture in the air gets into the plant material and causes it to discolor or mold. I don’t live in a humid climate and have never had this happen to me. I have heard of soapmakers in places like Florida and India encountering it though. Some of the best flowers to use in your homemade soap recipes include:

• Calendula
• Cornflowers
• Chamomile
• Goldenrod
• Lavender
• Poppyseeds
• Rose

Adding Dried Herbs to Soap Recipes

Dried herbs are easy to use in soap making. You can use them to infuse into your soaping oils or water, or you can sprinkle them into your soap batter or on the tops of your bars. Most dried herbs added whole will look dark in your finished bars. Think little dark brown and black speckles. Parsley flakes can hold their vibrant green a bit better and sage keeps a dark green tint.

For a speckled effect, use dried herbs that are finely pulsed — think of the consistency of ground coffee. Add about 1/2 to 1 teaspoon of dried herbs to every pound (454g) of soap in your recipe. Sprinkle it on your soap at ‘Trace’ and then stir it in. Pure, dried herbs can bleed a little into your soap as it cures, leaving a warm halo effect around each speckle.

Whole dried herb leaves can also be used to decorate the tops. Theoretically, they can be used in the soap batter too but be aware that they will re-hydrate after you start using the soap. Imagine full-sized, and potentially slimy, peppermint leaves in your soap. Dried herbs can also be infused into oil or water and then used in your soap recipes. The scent probably won’t hold but infusing herbs give color and possibly therapeutic value.

Adding Fresh Herbs to Soap Recipes

Adding fresh plant material to soap recipes runs the risk of ick and mold in your finished bars. Although it’s much more of an issue if you’re trying to add large chunks or pieces than if the material is thin, small, or pureed. That’s because the smaller the pieces are, the more likely the soap’s high pH being able to penetrate the material and stop microbes from growing.

Many soapmakers will be familiar with pureeing some vegetables, such as pumpkin to make pumpkin soap, but you could also puree fresh herbs if you wish. Do keep in mind that green herbal puree in soap recipes will turn tan to brown over time, though. It may also add a fibrous texture that you may or may not want.

But what about chopped herbs? Some are relatively dry and can be added fresh without worry of the soap spoiling. Rosemary, lavender leaves, and thyme can all be chopped and added fresh at 1-2 tsp per pound of oils in your soap recipe. Do practice caution when adding wetter herbs in this manner though. Unless chopped very finely or pureed, herbs such as basil and parsley can leave your soap bars mucky and spoiled.

Using Dried Flowers in Soap Recipes

In your soapmaking journey you will likely come across the purist soapmaking police. I just made that term up but I think you’ll understand what I mean. Many soapmakers stick to a certain ethos (or lack of one) and will try to convince you against doing things like decorating soap with dried flowers. You’ll hear all kinds of things as to why, but the most common one is that botanical decorations turn brown. There is an element of truth to this but it’s not as bad as it’s made out to be. I’ve also found that the color transition doesn’t usually happen immediately if you follow certain precautions.

Because of the water that’s in wet soap, many botanicals can absorb a small amount of high pH moisture. The type of flower or herb, the amount of moisture absorbed, and the age of the soap bar, are the main factors in whether decorations will brown. In my experience, rose petals as topper decorations tend to darken but stay similar to their original color for many months. The same goes for lavender. So if you’d like to decorate your soap batches with dried flowers, go for it! Just be aware that the color of the botanicals will fade over time, so try to make your soap to be used within about six months. Fading is also the case with many natural soap colorants.

Avoiding Brown Flowers

Many dried flowers such as cornflowers, chamomile, and rose petals will keep their color (for several months at least) if sprinkled as decorations on the tops of soap. There are some tips that I’d like to share if you’d like to keep the original color of dried flowers lasting for longer. First of all, unless it’s calendula flowers, don’t mix the flowers into the soap batter. If this happens, then they can go brown in a flash, and it can be quite unfortunate. For example, the beautiful purple color of lavender buds quickly changes to a medium to dark brown. And what also is that color and shape? If you’ve ever had mice in your home, you’ll understand immediately.

For most dried flowers, that means leaving them for decorating the tops of bars and soap loaves. When you do decorate, use a light hand and try not to push the decorations into the batter. The deeper the petals or flowers are, the more moisture they can pick up from the wet soap. If your soap recipe stays relatively soft after you unmold and cut it, you could wait a few days before pushing larger dried flowers, such as dried rose buds, into bars. It’s not a fail safe, since some recipes can take longer to saponify than others, but many will finish saponifying after two days. Waiting until the pH drops a bit and the soap dries, can help preserve the color of botanicals.

Another tip I have is to not insulate the soap after you decorate the tops of loaves. I used to think that it was the heat from this action that could turn the flower petals brown. I’m now more convinced that it’s because insulating locks alkaline moisture into them. I’ve seen soap decorated with rose petals turn instantly rusty colored after being insulated.

Add Dried Flowers to Cured Soap

There are two other tricks I have for you to ensure that dried botanicals stay true to their original color. Add them after your soap has fully cured. There are a few ways to do this, including simply tying dried flowers on with a ribbon or lace. You could also scatter dried flowers (and herbs!) on soap bars while packaging them up in translucent, or semi-translucent paper.

There’s also a way to get dried flowers to stick to cured soap. Spray the soap with witch hazel or isopropyl alcohol and place the flower petals on top. Leave them to dry completely and you’ll find the flowers stuck on by the end. Not as firmly as they were embedded in the soap, but it works, especially with smaller or thinner flowers. Though I’ve not tried it yet, it just occurred to me that pressed flowers could be attached this way too. Now that could be a beautiful decoration for perfectly flat bars of soap.

Mixing Flowers into Soap Recipes

We’ve already gone over how mixing dried flowers into soap batter can turn the petals brown. The same can go for infusions (tea) made with flowers. Sadly, this is the case for most flowers including rose petals and lavender. An exception to the rule is calendula. It holds its sunny yellow or orange color indefinitely.

It, and a few other types of dried flowers, can be infused into a carrier oil to naturally color soap. Calendula flowers come in both yellow and orange and I find the orange petals infuse beautifully into olive pomace oil and other light-colored oils. Infusing St Johns Wort flowers into light-colored carrier oil tints it into a deep red, which is useful in creating pink to coral colored soap. When using infused colored oil, you replace part or all of an un-infused oil, such as olive oil, with your infusion.

Using Fresh Flowers in Soap Recipes

You treat fresh flowers much the same as you would any wet plant material in soap — with caution. If you wish to use fresh flowers in soap, you should opt for pureeing them or using them in a water infusion. That way you can avoid any issues with spoilage, if not with discoloration. With a puree, it’s probably best add it after trace but an infusion can replace the water called for when making the lye solution. You can leave the petals in the infusion if you wish, too. Both the lye and the action of the immersion blender will pulverize the petals into small pieces.

Just keep in mind that most flower petals will turn your soap brown if you use them in a pureed form. Exceptions include calendula, rudbeckia (black-eyed Susan), goldenrod, and daffodils. These golden petaled flowers will all tint your soap buttery hues of yellow to orange. To make a puree, blend your fresh flower petals with enough water to make a thick soup. Use this puree to replace up to half of the water content of your soap recipe. You can also use fresh flowers in a water infusion, basically a tea.

Grow Herbs and Flowers for Soap Making

The herbs and flowers that you use to make handmade soap can come from a farmer’s market, a herbalist’s shop, or your own garden. Please be careful with flowers from supermarkets though, as many roses and other bouquet flowers are sprayed with pesticides and fungicides. Homegrown is best, and I think that using herbs and flowers from your garden in soap adds a special story to your handmade products. Just imagine soap decorated with your own rose petals or cornflowers!

On Lovely Greens, you can find a lot of tips for growing herbs and flowers for skincare recipes but one of the best resources for growing useful plants is my book. Skincare plants feature in chapter four, but you’ll also learn about plants to grow for the kitchen, home cleaning, natural dyeing, and herbal medicine.