Recipe for Natural Rose Geranium Soap coloured with Alkanet Root

Naturally coloured purple with Alkanet Root

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In this rose-geranium soap recipe you’ll use the natural colouring properties of Alkanet root, scent from my favourite essential oil, and dried rose petals to decorate. This is a type of Castile soap so the main oil in the recipe is olive oil. The additional coconut oil and castor oil are to help create beautiful bubbles, beeswax helps to harden the bars, and the shea butter makes the soap gentle and moisturising.

Natural Rose Geranium Soap Recipe by Lovely Greens


Alkanet Root gives soap a natural purple colour

As a natural soap maker I use essential oils and natural colors in my creations. In the soapmaking classes I give I also show students the wide range of ingredients you can use to create wholesome natural soaps. Each time it reiterates in my mind that there’s no need to use synthetic dyes to achieve beautiful results.


Alkanet is from a plant that grows in Mediterranean climates and produces rich, purple roots. When dried out and then either powdered or shredded, these roots will tint handmade soap from a pale lavender to a dark royal purple. Though you can add ground alkanet directly into your soap, I prefer to seep the roots in oil and then strain them out. More on that below.

Though difficult to grow in cool ,damp, climates or in acid soil, you can get a hold of Alkanna tinctoria seeds online. It’s a perennial plant and if you propagate it successfully, it grows well in alkaline/chalk soils and in climates that are warm and dry.

Rose Geranium Soap Recipe

12oz / 350g batch — makes 3 bars
7% superfatted*
Read my free 4-part soapmaking series here

Lye Solution
47g / 1.66oz Sodium Hydroxide
88g / 3oz Water
Optional: 3/4 tsp Sodium Lactate — adding this will make your soap become harder, faster

Solid oils
88g / 3oz Coconut Oil, Refined
11g / 0.37oz Shea Butter
7g / 0.25 oz Beeswax

Liquid oils
227g / 8oz Olive oil infused with Alkanet root
18g / 0.62oz Castor oil

Scenting & Decorating
4 drops Grapefruit Seed Extract
1 tsp Rose Geranium (Pelargonium graveolens) essential oil
Dried Rose Petals to decorate

Special Equipment needed

Digital Thermometer
Digital Kitchen Scale
Stick (Immersion) Blender
Silicone Loaf Soap Mould

Natural Rose Geranium Soap Recipe with dried Alkanet root for natural purple colour

Dried and shredded alkanet root looks like dark brownish purple wood chips

Step 1: Infuse the Alkanet into oil

There are two ways to go about extracting the natural purple colour from the Alkanet roots into oil. The first takes a little longer but is the way I do it. The second uses heat and will do the job quicker if you’re pressed for time.

  • Combine 10g / 0.35oz of shredded alkanet root with 500g / 17.5oz of Olive oil
  • Method 1: Combine the alkanet and oil in a glass container and set it in a sunny window. Leave to infuse for 4-6 weeks giving the bottle a gentle shake every week or so.
  • Method 2: Combine the alkanet and oil in a closed jar(s) that will fit inside a slow cooker. Place a small kitchen towel at the bottom of the slow cooker and then place your jar inside. Fill the slow cooker with water just short of the level of the oil in the jar and then set the cooker on low with the lid on. Leave for 10 to 12 hours or overnight.
  • Final step for either method: strain the alkanet root from the oil using a fine mesh strainer, cheese cloth, or clean nylon. Discard the roots and keep the oil for soap making.
Use alkanet-infused olive oil to make natural purple soap

Oil infused with alkanet root will be a rich red colour when ready

Step 2: Getting set up

Safety first! Make sure to be wearing closed-toe shoes, long sleeves, eye protection (goggles), and latex or washing-up gloves. You’ll be working with Sodium Hydroxide (Lye) and splashing a bit on your skin isn’t the most pleasant of experiences. To learn more about lye and lye safety read this piece on the equipment and safety needed for soapmaking.

You also need to have all of your ingredients measured and your work surface organised. Open a window for ventilation, close doors on pets and children, and have everything you need laid out:

  • Sodium Hydroxide and water measured into heat-proof containers: glass, pyrex, or polypropelene plastic
  • Solid oils measured into a small stainless steel pan.
  • Liquid oils measured into a bowl
  • Mould set out and ready. You’ll also need a light towel so have that ready too.
  • Stick blender plugged in and ready
  • Digital thermometer out
  • Utensils laid out: stainless steel spoon for stirring the lye solution, a small fine-mesh strainer, and a flexible spatula
  • Fragrance and extras at the ready: essential oil, grapefruit seed extract, and rose petals
  • Read all of the directions in this piece thoroughly before making your soap.
  • To read my free four-part series on natural soapmaking head over here
Natural Rose Geranium Soap Recipe by Lovely Greens

To get an even more vibrant purple, use alkanet-infused olive oil for all the olive oil in this recipe

Step 3: Create the Lye Solution

If you’re like me and have a window above your kitchen sink then you can work there. If not, you’ll need to create your lye solution near another window (or better yet, outside) for ventilation.

  • Holding the jug of water away from you and towards that open window, pour the lye crystals into the water and stir well. Steam, fumes, and heat are the product of water and dry lye combining. Be wary of all three.
  • Place the steaming jug of lye-water in the sink. Next fill the sink with a little water to help the lye solution cool. Use a basin if you’re working away from your sink.

Step 4: Heat the solid oils

Move away from the lye and begin melting the solid oils on the lowest heat possible on your hob. When there are just a few pieces of solid oil floating in the pan, turn off the heat and move the pan to a pot holder. Stir with your spatula until all of the oils are melted.

Step 5: Mix your oils

When the solid oils are melted, pour your liquid oils into the pan. Use the mini strainer when adding the alkanet-infused oil just to make sure any bits of root don’t end up in your soap. It’s not a big deal if they do, but they will cause little dark flecks. Also, use the spatula to get as much of the oils in as possible — castor oil has a real tendency to stick.

Now measure the temperature of your oils with your digital thermometer. You want to get it down to about 120°F / 49°C.

Step 6: Balance the temperatures

Once you have a read on your oil temperature, head back over to the lye solution and take its temperature too. It’s fine to go back and forth with the digital thermometer for both. If you’re opting to use the optional Sodium Lactate (which makes your soap harder) then add it to your lye solution when its temperature is below 130°F / 54°C

You’re aiming here to get the lye-solution and the oils in the pan to be within 5 degrees of each other in temperature. You also want that range to be around the 120°F / 49°C mark. You could go a little higher but lower temperatures will result in a less vibrant colour.

Step 7: Stick Blending

When the temperatures are balanced, it’s time to mix the lye-solution with the oils. Pour the lye-solution through the mini strainer (to catch any pieces that might not have dissolved) and into the pan of warm oils.

Next, place the stick blender into the pan and use it to stir the mixture together gently. The head of the stick blender should be completely immersed in the oil-lye solution. If it isn’t, you need to use a smaller pan.

Bring the stick blender to a stand-still in the centre of your pan and then press pulse for a few seconds. Then stir gently again for a few moments and repeat the stand-still stick blending.

Continue pulsing and stirring your soap batter until it hits a light ‘Trace’. This means that the batter thickens and if some of it dribbles down from the stick blender, it will leave a mark on the surface of your soap-batter before falling back in.

Don’t be alarmed at the colour of your soap right now — it will likely be grey or a greeny-blue-grey. This is totally normal and the colour will change to purple over time.

Step 8: Add the Fragrance

When your soap batter has thickened to a ‘light trace’ it’s time to stir in your fragrance and the Grapefruit Seed Extract which is an anti-oxidant. You do not need to use preservatives when making handmade soap. Anti-oxidants help keep the oils in your soap from going ‘rancid’.

Pour each of them into the soap batter and gently stir until they are all dispersed. Give it a good 20-30 seconds of stirring.

Natural Rose Geranium Soap Recipe by Lovely Greens

Decorate the top of your soap loaf with rose petals

Step 9: Mould & Decorate your Soap

Pour your soap batter into your silicone mould in a place where you can leave the mould for at least two days. If you’re using a Silicone Loaf Soap Mould like mine it will only come part of the way up. Use your spatula to get as much of your soap out of the pan and into your mould.

Settle the soap so that it has a flat top. You do this by gently shaking the mould.

The final touch is laying your dried rose petals on top, making sure to think about how you want to cut the loaf up into bars. When this is finished, cover the mould lightly with the towel making sure the towel doesn’t touch the top of the soap.

Step 10: Cut and Cure your Soap

After 48-36 hours you can pop your soap out of the mould. It may be sticky being that it’s an olive oil soap but if you pop the soap into the freezer for an hour before it can make this step easier. If you’ve used Sodium Lactate your soap should be fairly firm by now anyway though.

Leave your block of soap sitting on a piece of grease-proof or baking paper for another day or two before you cut it up if you’ve not frozen it. If it is frozen, you can cut it then and there. Use an ordinary kitchen knife and cutting board to slice it into bars.

Next is the hard part — waiting for your soap to ‘Cure’. Olive oil soap takes longer than other soaps so you’ll need to keep your bars on that grease-proof paper for another six weeks. Place them on a book-shelf or another place that’s airy and out of direct sunlight. The purple colour will continue to change over that time and the insides of your bars will eventually match the colour of the outsides.

Your soap needs all of those weeks to harden and finish turning into soap. It also needs time to allow the water to evaporate out. After your six weeks is up, your soap is ready to use.

Natural Rose Geranium Soap Recipe by Lovely Greens

* For those of you who have made soap before you might be confused as to how this recipe is ‘Superfatted’. Usually you do this by adding melted oils at ‘Trace’. The way we do it here is allow all of the oils to be superfatting oils by introducing them all to the lye-solution. That way a bit of each helps to superfat rather than just one added at the end.

6 Discussion to this post

  1. Darlene Salas says:

    Thank you so much for sharing your knowledge! What if you are using alkanet root powder. What is a good ration for this lovely purple?

    • I don’t use Alkanet root powder directly in soap since the texture can be a little scratchy. If you’re looking for an exfoliating soap then go for it and experiment — otherwise I’d recommend you stick with infusing the oils. You can use both the whole roots or the powder to infuse your oil.

  2. Laury says:

    If you are using alkanet root “powder”, how much would you put in the oil instead of the dried matter??

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