Drying and Curing – The Path to a Delicious Harvest

When a grower finally harvests ripe flowers, a moment of satisfaction arrives — and at the same time one of the most important stages of the entire season. The flavour, aroma and effect of the final dried material depend on the way you dry and cure the harvest. A few mistakes are enough for months of work to come to nothing. So how should you dry and cure it so that the result is worth it?

What do you imagine when you hear quality dried material?  A strong effect, pronounced aroma or delicate flavour? Probably all of these together. Behind these qualities are cannabinoids, terpenes and other substances that form in the plant and are stored in trichomes. To preserve as much of them as possible, you must handle the harvested plant material carefully during processing. Proper drying and the subsequent refining (curing) determine whether your harvest will smell of fruit or of wet hay.

Different drying methods

The first step towards a flawless harvest is gentle and slow drying. The aim is not merely to dry the plant material, but to do so in a way that preserves as many active compounds as possible in the dried material. These are hidden in trichomes, microscopic glands on the surface of flowers, leaves and stems, where cannabinoids and terpenes are formed. With rough handling, the trichome heads break off and fall from the flowers in the form of a fine resin-like powder. The trichomes on flowers are the most valuable; they contain the greatest amount of active compounds and have a higher monoterpene content than trichomes on leaves and stems.

The more you handle the plants, the more trichomes you will lose during drying. The gentlest method is to remove only the dried and yellow leaves from the plants and dry them whole, hanging upside down. This method ensures slow drying, which is important because herbs that dry too quickly lose terpenes and have a bitter taste. The optimal drying time is roughly 7 to 21 days at a temperature of 16-20 °C and relative humidity of 55%. During that time, the plant material should lose roughly 70–80% of its weight.

There is always a certain risk of mould during drying. This is especially true for large outdoor plants or those that have already been affected by mould. In such a case, remove all large leaves from the plants before drying. This will increase air circulation around the flowers. The flowers will dry a little better if you separate the plants into individual branches. Alternatively, you can dry the flowers divided into smaller parts on drying nets. Before that, however, do not forget to remove the small petals (wet trim).

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How to equip a drying room

A room for drying herbs must be well ventilated and completely darkened. Light degrades both cannabinoids and terpenes, and air circulation is important so that the plant material does not become damp and start to mould. If you do not have a suitable place in the house, a growbox (grow tent) with an activated extract fan will do for drying herbs.

Throughout the drying period, monitor the temperature and humidity in the drying room with a thermo-hygrometer. If the humidity rises too high, the best solution is a dehumidifier, on which you only need to set the desired humidity. When drying in a growbox, place the dehumidifier in the room with the grow tent, not directly inside it, so that the warm air does not dry the herbs too quickly.

You can tell well-dried flowers by the fact that they feel dry to the touch, spring back slightly and break off the stem easily. If the herbs crumble easily between your fingers, that is a sign of over-drying. This is not ideal, but all is not lost. If you place the dried material in a space with higher humidity (above 65%) for one or two days, it will regain some moisture. Check the flowers roughly every 6 hours.

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Trim and curing

If you did not do so during harvest, after drying it will be necessary to clean the plants of the remaining leaves, especially the small leaves around the flowers (dry trim). Trimming is painstaking work, and we recommend equipping yourself with sharp spring-loaded scissors with a sharp tip. Disposable gloves will also come in handy, because the resin of some medicinal plants can irritate the skin. For cleaning tools and hands, do not forget to add disinfectant alcohol to your basket.

In theory, the dried and trimmed buds can be used immediately; however, you can still improve the quality of the dried plant material. Curing (refining) is a technique in which the dried material is left to mature for several weeks to months under controlled conditions. During this time, residual moisture in the dried material spreads evenly and the plant material loses some chlorophyll, which has a bitter taste.

Curing is usually carried out in glass or metal jars that can be sealed airtight. Fill the containers with the trimmed flowers to about three quarters full so that there is some space for air. You can add a humidity control sachet inside, which will ensure that maturation takes place under optimal conditions. Finally, store the maturing dried material in a dark place with a stable temperature in the range of 15-18 °C.

Depending on the cultivar and personal preference, you can leave the dried material to mature for several weeks to months. During the first week, open the containers every day and allow the dried material to air out once a day for about 20-30 minutes, but be careful about the surrounding humidity. If it is raining outside, the humidity at home can also be around 70-85%, and the dried material will absorb it very quickly. It is therefore a good idea, in rainy weather, to seal the room off from the outside environment before opening the container and measure the humidity in the room where the container with the maturing material will be opened. Before closing it, gently mix the flowers in the container with a clean tool so that fresh air reaches all of them. In the second week of curing, it is enough to open the containers two to three times. In the following weeks and months, air the dried material at least once a week.

For more tips and guides on legal cultivation, visit our Higarden blog for beginners and advanced growers.