by Nebula Haze
The dreaded cannabis “hay smell” after drying marijuana buds has been a thorn in the side of home growers since we first started growing weed. Sometimes the terrible smell appears during the drying process, and sometimes it happens after buds get put in jars for curing.
It’s unbelievably frustrating to get hay smell after all your hard work, and many growers can’t figure out why it happens. What causes marijuana buds to smell “harsh” or like “fresh cut grass” or “hay” after they’ve been dried or cured? Today I’ll teach you why it happens and how to avoid it.
Why do buds sometimes smell bad like musty hay after being dried?
This often happens to beginner cannabis growers:
- Buds smell good before harvest
- Musty “hay” smell after drying
- Curing buds in jars helps fix the smell …or sometimes it makes buds smell worse!
Stop this vicious cycle!
Did you know you can dry buds in the right way and they smell delightful from the moment they’re done drying? At that point, curing buds in jars will enhance the smell further and make buds smooth to smoke, but you don’t have any point where they smell “bad”.
5 Tactics to Dry & Cure Cannabis Buds without Hay Smell
This section will teach you how to grow the best-smelling marijuana buds possible.
1.) Air dry in a cool space if possible
Cut off individual branches and change them upside down in a lightly ventilated space. Some growers put their buds on mesh drying racks but that leaves flat spots on the buds. Keep the temperature between 60-70°F (15-20°C) while drying. I set my AC to the lowest setting and dry buds in a grow tent with gentle air circulation. Perfect buds every time. If your drying space is warm most of the time (like the inside of many closets), consider one of the next two options if possible.
Keep the temperature under 70°F/20°C while air-drying in a gently ventilated area to produce excellent buds with no hay smell every time. Buds come out perfect after 7-10 days.
2.) Or use a cannabis bud dryer
An alternative method is a cannabis-specific dryer/dehydrator like the HerbsNow dryer. Note: I have no affiliation with this company; I’m just sharing my personal experience. The heat settings on most food dehydrators are too high and will cook your weed but the HerbsNow uses gentle warmth. Even though it’s a cannabis-specific dryer, you must use it properly or you’ll get poor results because buds are easy to over-dry. Click here to read my full review of the HerbsNow dryer.
Cannabis-specific dryer gets good results when used properly in a variety of different environments, but it’s super easy to over-dry your weed if you aren’t careful. They work well even in a warm drying space, but they tend to get worse results in low humidity.
3.) Or air dry in a cardboard box or paper bag
If you don’t have a cool ventilated space and can’t get a dryer, your best option is air-drying in a box (or even in a paper bag) in a room. The properties of paper/cardboard help create a good bud drying environment, especially combined with some gentle air movement around the box. Hang the buds upside down from within the box like your own personal drying chamber. Don’t let the buds touch each other and make sure there is some air circulation. For example, leave the top of the box slightly open or cut some slits in the sides of the box. In the room, blow a fan towards a wall (not directly at the box unless it’s a weak fan) to ensure some air movement. Smell the inside of the box while air drying. If it smells at all musty it needs more air, otherwise try to minimize airflow so buds don’t dry too fast. Just remember that buds are more likely to gain hay smell when air-dried in a warm environment, so try to keep buds cool while air-drying if possible.
Drying in a cardboard box (or paper bag) is a great old-school but effective choice to reduce hay smell when you don’t have a cool drying space and can’t get a dryer. Boxes also help buds dry better if you have low humidity.
4.) Dry buds until small stems snap instead of bend
Buds can get musty if you put them in jars before they are fully dry. These two tests help ensure buds are fully dry: The small stems will snap instead of bend and the buds will pop off the stem without making strings. If you have to use scissors to cut off the buds cleanly because they’re taking stringy bits of stem, it means they’re too wet on the inside and need to be dried further.
How to tell when cannabis buds are fully dried:
5.) Monitor humidity of buds in jars (keep under 60% RH)
Generally, it’s recommended to make sure humidity is 62% or lower, but if you’re worried about hay smell, stay under 60% RH to be safe. Musty smell can be the result of mold or bacteria growth, so you need to make sure buds aren’t too wet in jars or wherever you’re storing buds. Sometimes the outsides of buds will get more wet over time as water works its way out of the middle, which can trigger the growth of unwanted organisms. It can be helpful to monitor buds with a hygrometer. If you’re having trouble making buds dry enough (for example because of high humidity where you live), get a Boveda or Boost humidipak, which will help suck up extra moisture out of the buds. These packs also help maintain the perfect humidity in jars over time so you usually don’t even need a hygrometer. They work by collecting extra moisture in specialized crystals contained inside the packet. The packets feel soft at first and need to be replaced once they get hard. They’re also handy to rehydrate buds that got overdried.
- Buds that feel moist are too wet and need to be dried more before being closed up in jars.
- Monitor humidity with mini hygrometers in your jars to ensure it doesn’t go over 60%
- Use 58% humidipaks to maintain humidity and help dry out too-wet buds.
Use 58% humidity-control packs to reduce the chance of hay smell developing during curing and storage.
Why do poor drying conditions and too much moisture during storage make cannabis buds smell bad?
When I first started growing cannabis (click here to learn how to grow weed) I learned that hay smell after the drying process was caused by green chlorophyll in the buds that did not break down properly. I was told that drying buds too fast is the cause, and drying buds slow was the solution.
Note: Parts of this are going to get controversial for some growers because it goes against common growing wisdom. Please read with an open mind and think about whether this matches your experiences with drying. I know some growers will disagree with me but the hay smell problem causes too much pain to home cannabis growers for me to keep this knowledge to myself even if it causes blowback. Please don’t hesitate to contact us and share your thoughts whether you agree or disagree.
What growers said causes cannabis hay smell: Green chlorophyll in the buds that did not break down properly from drying too fast.
What I think causes hay smell: Microorganisms like mold or bacteria (often invisible to the naked eye).
Hear me out. I know this isn’t what anyone wants to hear but let me lay out my evidence. I’ll share exactly how I came to this conclusion.
What’s that hay smell?
They said the solution is to dry buds slow
For my first cannabis harvest, I hung my weed in a closet with a fan pointed at the wall. All the buds were dry and crispy in only a day or two. They didn’t smell like hay but looked bad and were harsh to smoke. Luckily, if you cure buds in jars, especially with a Boveda humidity pack to rehydrate them, it helps resuscitate buds and make them smokable with a better smell.
I was disappointed. I researched online and learned that the reason for my poor results was I dried buds too fast. Makes sense.
For the next cannabis harvest, I dried them in the same closet with the door cracked but no fan. It took them 3 days to dry, so it was taking longer, and this time they had a musty hay smell that was even worse than when they dried the first time.
The next time I tried hanging the entire plant upside down to dry because I read that’s a good way to dry buds slow, and it took a full 7 days before the buds were dry. Still hay smell! Not only that, the buds in the middle were covered in mold 😭 I threw that whole harvest away.
This drove me nuts as I tried to figure out what I was doing wrong. I’d spend 4 months growing an incredible harvest that smelled wonderful, and yet after drying I was left with a bunch of weed I was embarrassed to share with my friends, or even worse had to throw away. Curing the buds helped a lot, especially over several weeks, but I wanted weed that smelled good immediately after drying like I knew the professionals were producing.
Then they told me hay smell was caused by heat and low humidity
I kept asking growers what worked and didn’t work for them when it came to drying weed. Some growers had the same issues as me, and others seemed to have no problem drying buds even just in the closet. What was making the difference? Why did some growers get good results and some got bad? I was determined to find out.
Several growers told me the cause of hay smell was drying buds in a hot place or with low humidity. They said that the heat and low humidity reduced chlorophyll breakdown by causing buds to dry too fast. That all made sense to me. I knew it was kind of hot in my closet and I hadn’t tested the humidity so maybe it was dry. I got an AC and actually cooled the whole room to about 62°F/17°C. This time I dried buds in my tent with a slight breeze from the Cloudline exhaust fan on its ultra-gentle first setting. The humidity in the room was about 50% RH.
Voila! That fixed it!
I thought I knew the answer; Cool temperature during drying
My buds took about 10 days to dry. I waited until the small stems snapped instead of bent, and when the buds came out of the tents and into jars they were perfect. They still smelled the same (slightly muted) but had zero hint of hay smell. After curing them for 2 weeks they looked better and smelled better than the weed from the dispensary. These buds smoked smooth and kicked your butt with their effects.
Buds came out perfect when I cooled the room to 62°F/17°C and dried them in a grow tent
But how many growers can do that? I happen to live in a place where it gets sweltering hot in the summer so it makes sense for me to get an AC, but how many people can afford to cool a whole room just to dry their weed? I started searching for alternative effective drying methods that actually made sense for home growers.
Enter the HerbsNow dryer. It seemed to disprove my theory.
I saw a product on Instagram called HerbsNow Dryer ($200). Note: I have no affiliation with this company. I am just sharing my personal experience. It claimed to dry weed in just 4 days. It appeared to be a food dehydrator set on a 96-hour timer. A key difference was the heat was turned down to just 80°F/27°C, while a normal food dehydrator cannot be set below 100°F/37°C.
I actually bought the dryer specifically to prove that it would do a bad job. After the experience I just described, I thought that the secret was for buds to be cool during drying. So how could a dryer that heats them up cause good results? I thought, “This will be great content for GrowWeedEasy.com to show how heat is the real culprit to bad drying results.” Haha I was about to be proven wrong.
In my tests, the HerbsNow dryer produced just as good buds as air-drying. I tested it first with just a few plants. I air-dried some and dried some in the dryer. When they came out I honestly couldn’t tell the difference. I then got the buds lab tested and their THC and terpene percentages were comparable between air drying in a cold room vs drying in the HerbsNow. Huh. That seemed like it must be a fluke. So I tested it on 16 different plants over the next few months, and got all 32 samples tested at the lab. The buds dried in the dryer vs air-dried in the tent tested almost identically. And none of them had hay smell. That’s great for growers who can’t keep a cool drying place, but that put a huge wrench in my theory that the hay smell was caused by heat. Check out my full review of the HerbsNow dryer for pictures, lab reports, plus tips and tricks.
If it wasn’t heat that was causing hay smell, what was it?
And this is where it gets gross. I wanted to figure out what could cause hay smell in heat when air drying, but wouldn’t cause hay smell in a dryer.
I asked myself, what growing environments cause hay smell? I made a list.
Air drying (hanging buds upside down) – What causes hay smell in my experience and from the experience of GrowWeedEasy.com readers
- Warm temperature above 75°F / 23°C increase the chance of bad smells when air drying
- Rarely get hay smell when air-drying in temperatures under 70°F/20°C
- Hay smell is more common with no ventilation, lack of fresh air, and/or no air movement
- Hay smell is more common when buds are spaced close together or some buds are touching
- Hay smell often happens when humidity is above 60% RH, especially when combined with warmth
And then it hit me. It was organisms. Living things. Organisms and mold love growing in hot humid places with stagnant air. Many growers may be familiar with powdery white mildew, which appears on plants in a similar environment. Anyone who’s had a mold problem in their house knows it’s usually concentrated in places with high humidity and moisture. But living things have a hard time growing in an environment with constantly moving air like an air dryer. In fact, that’s part of why food dehydrators are designed the way they are – to prevent bad stuff from growing on your food as it gets dehydrated.
So there you have it, that’s my theory as to what causes hay smell. It’s not proven but seems to explain everything I’ve seen and experienced so far.
What about dryness and over-drying?
I think this is the confounding factor that made it so hard for growers to realize it’s actually been microorganisms causing hay smell. When you over-dry weed, or dry it really fast, or dry it under too much heat, it gets gross. Although it doesn’t take on the same “hay smell” I think it often gets lumped in. But I believe that these are two separate drying problems. Over-drying and low humidity drying is one problem, and hay smell is another one.
- Over-drying and low humidity are real problems that can cause buds to be harsh, crispy, and/or not smell like weed
- “Hay smell” seems to happen most in stagnant air
- I believe hay smell and low humidity/overdrying are two different problems that often get lumped in together
What about trimming buds before drying?
Some growers have noticed that trimming buds before the drying process can contribute to harshness and possibly hay smell. I personally haven’t had that experience, but it’s common for growers to experience this so I need to experiment mroe to try to explain. Perhaps the buds are more likely to dry unevenly when they don’t have the protective covering of leaves. I also wonder if trimming the bud opens the inside of the plant to the outside world and increases the chance of bad organisms to grow at those wounds. I’d love to hear your thoughts and your experiences.
Why does curing help hay smell then?
Ok this is really, really gross. But what if it’s just that the microorganisms go through their life and die as the buds cure in jars? If they’re not living, I wonder if the smell goes away…
Why does high humidity or too much moisture in jars cause hay smell?
You guessed it. Water and high humidity power the growth of microorganisms.
If you have anything to add to this page, please contact me with the following information: how you dried the buds, the temperature, the humidity while drying, and a picture would be greatly appreciated.
All right, I’ve laid out my evidence. I want to know what you think. Share your thoughts. If you disagree, I still want to hear your opinion. We are all here trying to gain knowledge and help home growers grow the best weed possible. We’re in this together.
