Viability of Using Freeze Dried Herbs to Improve the Quality and Performance of Value-Added Herbal Products

Final report for FNC18-1126

Project Type: Farmer/Rancher
Funds awarded in 2018: $6,929.00
Projected End Date: 02/28/2020
Grant Recipient: Frozen in Thyme
Region: North Central
State: Wisconsin
Project Coordinator:
Sheri Howard
Frozen In Thyme Herbs
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Project Information

Description of operation:

We currently have 7 acres of farm/forest land, with 3 acres tillable. This is new land. We are in the process of transplanting perennial herbs from previously rented land and greenhouse space to the new land. We are waiting to hear if we have been awarded an EQUIP grant for a new high tunnel that would help extend the season of our herbs. We are also working with EQUIP to fence in the property for deer control. We have been growing herbs for 3 years on organically certified land. Our hope is to have our new land certified organic within two years. We are also in the process of completing a food processing kitchen for our freeze drying business, and plan to have it certified as well. This will allow us to sell freeze dried herbs for culinary purposes, such as teas.


Today’s herbalists prepare their products using a combination of fresh and dried herbs. While fresh herbs impart a higher degree of color, aroma, flavor, and active constituents, they also introduce moisture into the process that can lead to molding. For this reason most herbalists turn to dried herbs for use in their products. Dried herbs eliminate much of the moisture, but also lose many of the properties that make the herbs beneficial to the final product. Access to locally and sustainably grown dried herbs is also very limited.

Freeze drying provides a cost effective and improved alternative to preserving herbs. It removes 98%+ of the moisture while preserving most of the color, flavor, aroma, and constituents found in fresh herbs. The availability of home freeze dryers makes it possible for artisan producers to have access to locally grown, freeze dried herbs and the potential to improve the quality of their products.

This project is designed to determine if freeze dried herbs can be successfully used in herbal products, and if there is any noticeable improvement in the quality of the products. It will also determine if there is perceived market value in having access to locally and sustainably grown herbs.

Project Objectives:
  1. Determine the viability of using freeze dried herbs in the manufacture of herbal products (tinctures, creams, infused oils, salves, lip balms, etc.) including performance during processing, and quality of final product.
  2. Identify perceived improvements by producers of customers in the quality, effectiveness, and market value of herbal products manufactured with freeze dried herbs in their products.
  3. Identify opportunities for local artisans producing herbal products to increase their market share by using freeze dried vs traditionally dried herbs.
  4. Introduce opportunities for local herb growers to diversify their product offerings by freeze drying their herbs.


Materials and methods:

Finding local herbalists willing to participate in the research grant has been more difficult than I expected. I approached the members of my local chapter of the Herb Society of America only to find that none of them actually produce products for sale. I also contacted a local herbal product retail store that sells items on consignment. I found an herbalist with a farm about 30 miles to the north who took several samples of my freeze dried herbs to try in her recipes. Unfortunately, she went out of business unexpectedly. I also contacted a few of the soap and salve makers who sell locally, and found that many of them are using essential oils instead of dried herbs.

To continue getting the word out, I have been distributing samples of my freeze dried herbs to members of the Herb Society, and enlisting their help to find willing participants. Originally my plan was to stay local in northeastern WI. I'm broadening my search to include all of WI. I now have two committed participants. Fragrant Isle Lavender Farm on Washington Island has committed to hosting a tea tasting event using three blends of herbal teas at their store over one weekend in July. Jane Hawley-Stevens of Four Elements Herbals in North Freedom has also committed to making several of her recipes with my herbs. Jane is one of the largest organic herbal product producers in the state, and has been a mentor of mine for several years. She will be starting her testing in June when she returns from an upcoming overseas trip. I do believe that having Jane involved in my study will go a long way towards getting other herbalists to join the study.

Research results and discussion:

Overview and Early Observations

The original project goals and objectives for this research project developed from my own personal experience using freeze dried herbs in herbal projects, as well as feedback from friends and peers in the herbal community. The idea of freeze drying the herbs came from my dissatisfaction with the quality of traditionally dried herbs I attempted to use in my own herbal products. Both air dried herbs and those dried in a dehydrator lost their vibrant colors, fragrance, and taste almost immediately.

After purchasing a home freeze drying unit for our personal use, I experimented with culinary and medicinal herbs we grew and had in excess of what could be used or sold fresh. I’ll discuss some tips and best practices for freeze drying herbs later in this report. The results of my experiments were incredible. The herbs had the look, smell, and taste of fresh harvest.

I shared some of my early freeze dried products with both local growers and those using herbs in their products. The response was overwhelmingly positive and gave me the idea for expanding my research into potential marketability. The SARE Grant was the perfect choice.

It took some time to grow and freeze dry enough inventory to support the project. Even at that, I only grow a finite number of herbs, and I found that some tough roots tend to do better when traditionally dried. I reached out to a number of local shops, and individuals making single products for sale such as soaps, essential oils, and creams. I sent out many samples and followed up with phone calls. Initially there was a fair amount of interest in participating.

A few things become immediately apparent at this stage. First, many of the recipes included herbs and other ingredients I did not personally grow and could not obtain fresh in order to freeze dry for the project. This meant that only a portion of the ingredients in many of the recipes could actually be substituted with freeze dried herbs therefore masking the actual product comparison. I was prepared to provide or pay for the ingredients for each comparative batch as an incentive to participate. However, many of the recipes had several ingredients, some of which were very pricey. This caused me to change my requirements to using recipes with only a small number of common ingredients in them.

The second thing I realized is that many of the artisan producers were using essential oils instead of actual herbs to make their products. I found this to be the case with most of the soap makers as well as those making creams and lotions. I also eliminated tinctures because most require a substantial period of time to prepare, and it would be difficult for a consumer to tell the difference using smell, taste, and visual comparison. That left me with teas, honey infusions, and syrups.

The third thing I realized was that artisan producers are very sensitive to sharing or exposing their proprietary recipes with others. Even though I didn’t ask them to share the actual recipes, just the ingredients used, most simply stopped communicating with me even after I sent them herbs, packaging materials, etc. I also got the sense that they were unwilling to have their customers compare their products using both traditionally dried herbs and freeze dried herbs. I wondered that if there was a clear consensus that the products were better with freeze dried herbs, would they still be included to purchase the original products?

The final thing I realized early on was that most herbal product producers are running on tight margins and purchasing their products as cheaply as possible. Because the process is more involved, the price points for freeze dried products is somewhat higher than traditionally dried herbs. From a retail perspective, the price of the final products would have to be higher as well. The market for herbal products is very competitive, so I can understand the concerns about pricing themselves out of the market.

In the end, I received only two product comparisons back – an infused honey and a tea. The small number of consumers who tasted the comparisons overwhelmingly noticed the difference between the freeze dried samples and the traditional recipes. I suspect that the results would not have been the same for creams, salves, balms, lotions, or soaps because there are usually fragrances added that would mask the herbal products. Taste ended up being the best indicator of the value of using freeze dried herbs. The extremely small sampling is not enough to draw any conclusions around how products made with freeze dried herbs would sell in the open market.

Other Observations

Along this journey I was fortunate enough to meet a clinical herbalist with a private practice and a wellness center retail shop. Her focus was on product quality and how they can improve overall health. She was much more interested in the use of freeze dried herbs, especially in her teas. She also grew some of her own herbs and liked the idea that she could have them custom freeze dried to build up her inventory. Over the last year and a half, we have developed a friendship and a great business relationship. I custom grow herbs for her to use both fresh and freeze dried, and I freeze dry herbs she has grown in abundance.

The development of this arrangement created a need for our business to have a certified food processing facility in which to freeze dry consumable products. My husband and I invested in several large freeze dryers and built a certified food processing facility in our residence. We became licensed in 2020, and have been expanding beyond herbs to fruits, vegetables, and custom freeze drying services. Over the last nine months we’ve seen a large increase in orders for freeze dried tea blends, custom freeze drying products customers grow or source themselves, and surplus harvests from local farmers. We are exploring other opportunities to keep the freeze dryers in production as often as possible.

Technical Notes

Freeze Drying Tips

  1. Once harvested, fresh herbs should be quickly processed for freeze drying or refrigerated until processing can be completed.
  2. Try not to wash herbs if possible.
  3. Straw or other mulch under the plants helps keep the harvest clean.
  4. Keep the leaves and flowers as whole as possible prior to freeze drying. For example, keep basil leaves whole rather then cutting them. Strip things like thyme and oregano off older/thicker stems, but keep the sprigs whole if the stems are supple and green. If you use them whole, keep them whole.
  5. Keep individual freeze dryer trays isolated to a single herb if possible. The freeze dryer can be loaded with multiple products on separate trays.
  6. Lower the drying temperature on the freeze dryer to between 90 and 95 degrees. Do not adjust for time.
  7. To load more volume on trays, stack trays on top of each other for 10-15 minutes to compress soft leaves and stems. Then add more product to just above the top of the tray.
  8. If the leaves/flowers are large and make it difficult to put volume on the trays, you may need to cut them into smaller pieces. Try to keep the cutting to a minimum for long term storage. If you are packaging for resale immediately, it may be more cost effect to cut/chop to size before freeze drying.
  9. If you are freeze drying seeds (or products with seeds in them), consider adding desiccants rather than oxygen absorbers. Seeds are very difficult to dry completely and can cause your product to re-hydrate after sealing if there is still moisture in them.
  10. Purchase a moisture meter to check moisture on your products before removing them from the freeze dryer. If necessary, add more drying time.


Packaging Tips

  1. If you are harvesting and freeze drying for long term storage, you’ll get the best results storing in 7mil mylar bags. They are available in 1 gallon, 2.5 gallon, and 5 gallon bags.
  2. The best bags for storing herbs without crushing them are gusseted bags with zip lock tops. Here are a few links to bags: Top Mylar; Pack Fresh USA . occasionally you can find their products on Amazon.
  3. If you have larger volumes of single product to freeze dry for long-term storage, store in the largest appropriate bag with oxygen absorber. Then you can repackage into smaller bags for resale.
  4. Link to proper oxygen absorber guidelines:
  5. If you are packaging for near-term use rather than long-term, there is no need to use oxygen absorbers.
  6. If you are powdering your freeze dried products, add a desiccant rather than an oxygen absorber to keep it from clumping. Also, package powdered products in smaller bags (1/2 pints or pints) to keep them as fresh as possible.
  7. You can also use mason jars for storage, especially if you only have a small amount of product or you use it frequently. Try to store in a cool, dark place and use a lid and ring rather than a plastic screw on cap. The plastic caps are not airtight.
  8. If you open your packaging frequently to use the product, replace the oxygen absorber periodically to keep it fresh.
  9. Re-hydration guidelines book:



We tried to lay out as scientific of a process as possible to get clean results. In the end, there were just too many variables that were outside of our control to keep the project on track and in scope. With that said, having given away many, many samples over the last few years and used the freeze dried herbs in our own products, I have no doubts about the improved quality of freeze dried over traditionally dried herbs.

Herbalists tend to be more quality conscious than price conscious, and were much more open to trying the freeze dried herbs. I believe there will be a market for both fresh and freeze dried herbs in apothecary shops, alternative wellness centers, and with private practice herbalists. We will continue to foster new relationships in this area.

In order to build up sufficient inventory to have product available for resale, we will continue increasing the amount of herbs we are growing and freeze drying. We have plans to put more land into production over the next three years. It can be a challenge to develop both a small farm and a freeze drying business at the same time - especially with limited staff. By focusing on selling fresh herbs when they are in season and freeze drying the surplus for winter sales, we hope to find the balance between farming and freeze drying. Adding fruits and vegetables to our freeze drying production has also helped improve profitability to ensure the business is successful.

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

15 Consultations
1 Published press articles, newsletters
3 Webinars / talks / presentations
1 Other educational activities: I participated in a Farm to School program to educate high school students on the process of freeze drying foods.

Participation Summary:

1 Farmers participated
1 Ag professionals participated
Education/outreach description:

I participated in one interview for the Green Bay Press after the 2018 SARE grant recipients were announced. The article was published online and the link is listed below. I gave a presentation to the members of the Northeast Chapter of the WI Herb Society organization on the grant and my goals for finding participants. In August I attended a three-day herb growers intensive at Four Elements Herb Farm in Baraboo, WI along with six other herb growers. I brought samples of my freeze dried herbs, which we sampled in teas and a few simple products during the intensive. I explained the purpose of the grant research. I have met with the owners of a local herb store, Sweet Willow, to discuss the grant, and provide samples for them. They are willing to host a meet and greet with some of the herbalists who sell their products in the store. Unfortunately, they have decided to close the store in June, so it will be a tight schedule to organize the meet and greet.

Learning Outcomes

3 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

Notes: See Results and Discussion for more lessons learned.

  1. We have a very small farm and just two of us working it. Trying to grow our own herbs to use in this research grant was a mistake. We simply don't grow a large enough variety of herbs to meet the needs of the various recipes that could be used in this study. We would have needed access to a large herb grower in our area in order to obtain enough fresh herbs to meet the scope of the project, and there none in our vicinity.
  2. Because we had a limited variety of herbs to choose from, we had to look for recipes with no more than 3-4 ingredients in them. This was small, even for teas.
  3. We lost some opportunities along the way to sell some freeze dried products that could have been used in a retail environment because we didn't have a licensed food processing facility to begin with. We made the decision to build the facility in our home mid-way through the project. This set us back in our timeline, and we lost some momentum as well. Now that it is up and running, we realize we should have had it in place before we started that project.
  4. Some of the herbal product makers we approached about helping with the grant actually went out of business within the first year of the project. We would have done better to find larger businesses willing to participate.
  5. Many of the herbal product makers are using essential oils instead of fresh or dried herbs. This narrowed down the prospective participants. Better research up front would have gone a long way towards avoiding some of these mistakes.
  6. Herbal product makers expressed concern over the higher price of using freeze dried ingredients in their products. The market is price competitive and consumers may not be willing to pay more for differences they cannot easily see.
  7. Herbalists were much more interested in higher quality ingredients than those making soaps, lotions, salves, etc. for resale.

Project Outcomes

3 New working collaborations
Success stories:

Throughout the first year I really found myself having to educate people on freeze drying as a preservation method. Very few people understood the process, which I think contributed to my slow start. I have given away 50+ samples of herbs for people to try in various recipes, and only recently (within the last few month) started getting responses back from my follow up email.

I made the decision to retire from my part-time day job in order to devote more time to getting my new farm up and running, my food processing kitchen built and certified, and finding participants for the grant research project. I am confident that I can 'catch up' on the activities needed to complete the study. I am very grateful and excited to have Jane Hawley-Stevens participating in the study. Her contributions will help give the study validity, especially for those herbal product producers who were hesitant to work with someone they didn't know.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.