Is Home-Grown Always Better? Exploring Herbal Quality and Standards

We often assume that one of the best reasons to grow your own herbs is to ensure we are getting the best quality. But is that really the case? The quality of herbs can be affected by numerous factors, including local ecosystems, soil composition, seasonal weather conditions, as well as the methods used for harvesting, processing, and preparation. So, can we confidently say that home-grown herbs are always better?

Of course, what is ‘better’ is often subjective and depends on the intended purpose. Growing herbs isn’t just about how they are ‘useful’ to us – many of us grow them simply for the joy of having these plants in our gardens. However, when growing herbs for use in herbal preparations, we naturally aim for the highest quality. To assess this, we usually rely on our senses in a process known in the Herbal Quality Control world as ‘organoleptic testing’. This involves evaluating the colour, aroma, texture, and taste of the herbs to ensure their quality, freshness and appeal. This sensory and more ‘vitalistic’ approach is an essential part of shopping, buying, cooking and eating. It’s also an essential part of being a gardener, grower and herbalist. 

There are also more objective scientific methods for assessing herbal quality by measuring the quantity and quality of specific phytochemical compounds. These tests involve extracting the desired compounds via methods such as distillation, solvent extraction, CO2 extraction, pressing and soaking to isolate the essential oils, resins, mucilage, flavonoids, alkaloids etc by using various forms of chromatography and physical tests, such as swell tests. Some of the equipment for these tests is easy to access and affordable to use whilst some is very expensive and needs skilled technicians to manage. 

What are Pharmacopoeia Grade herbs?

The methods for these tests and the desired levels of phytochemicals are often described in national pharmacopoeias. A pharmacopoeia is an official reference text that provides authoritative standards for the quality, purity, strength, and identity of medicines and herbal medicines. It serves as a legal and scientific guide for pharmaceutical manufacturing, quality control, and regulatory compliance. 

For example, the European and the British pharmacopoeias have over 100 monographs on herbs (as well as over 2000 on pharmaceutical drug ingredients). The Indian and Chinese pharmacopoeias have hundreds of herbs in their National Pharmacopoeias. Its important to note that the pharmacopoeia sets the minimum standard for therapeutic grade herbs determining the correct botanical species, defining maximum levels of microbiological, toxic element (heavy metals), pesticide and environmental contaminants, as well as minimum levels of so-called marker or active compound phytonutrients such as volatile oils, flavonoids and alkaloids.

What are Food Grade herbs?

Food grade herbs and foods are what we can commonly buy in shops and is the quality available from most herb suppliers.  These standards oversee hygiene and contaminants, as well as phytonutrient compounds. These requirements are usually determined by the Food Standards Agency but also added to by bodies such as The European Herbal Infusion Association and The International Standards Committee ISO 6571/1984. In terms of herbal quality, the food grade found in teas and supplements tends to be less rigorous in terms of contaminants and is 50-100% less concentrated in marker compounds than Pharmacopoeia grade.

For example, compare the different essential oil standards for three of the most popular herbs used in teas and supplements where food grade is 100% less than pharmacopoeial:

So, how do home-grown herbs compare to the Pharmacopeia and Food Grades standards?

Having made many herbal teas and tinctures from the herbs we grow in the Earthsong Seeds nursery, we have been curious to find out how they compare with the pharmacopeia and food grade standards. From an organoleptic perspective, there’s no question – they taste, smell, look and feel exceptional. But how do they perform in more objective, scientific tests?

To answer this question we started a little project in 2024 to test the essential oil content of some the aromatic herbs that we grow in our nursery. To get accurate results we sent our dried samples to a specialist laboratory in France, and the results have been fascinating.

In almost every case the essential oil content has been higher than the minimum amount specified in the British pharmacopoeia, and in some cases they have been spectacularly higher. German chamomile – our most popular seed – led the way with 1.3% essential oil (or 13.2 ml/kg), which is 230% higher than the pharmacopoeia standard, and an incredible 560% higher than food grade standard! Angelica has had similarly high results with 0.67% essential oil (6.7 ml/kg), 238% higher than the pharmacopoeia standard. Of all of our tests, only yarrow, which was wild-harvested from our organic meadow, had an essential oil content lower than the pharmacopoeia standard. See the full list of results at the bottom of the page.

These are of course the results from just one round of tests, and it is likely that they will vary from year to year. But already we can see that home-grown herbs can yield exceptional results, and in many cases be much better quality than herbs bought from a shop. We’re looking forward to doing more tests in 2025 and will keep updating the results here. Till then, keep growing your own!