Cloning used to be something exclusively reserved for the green-thumbed cultivator. But now thanks to advances in cannabis cultivation technology, it’s as easy as growing from seeds.
Humidity domes make growing cannabis from clones easy — and Grobo makes it even easier than that. We’ll walk you through everything you need to know about growing clones in a humidity dome.
What Is a Humidity Dome?
In the simplest terms, a humidity dome is a piece of plastic. It sits on top of propagators and seed trays. Its purpose is to keep the humidity and temperature levels high within the dome while allowing the plant space to grow.
Humidity domes are made of plastic generally, mostly due to the low cost and flexibility in shape. They help keep your plant at the ideal temperature of around 50 to 65 degrees Fahrenheit. They’re mainly for use indoors as most homes don’t have a high enough humidity or temperature for clones to thrive.
Your humidity dome is only used in the first part of your plant’s life cycle, either for clones or seedlings. For the purposes of this article, we’ll be discussing clones exclusively, but you can find more information on growing from seeds on our blog.
When Is a Clone Ready to Leave a Humidity Dome?
There’s one simple answer to the question “how long should clones be kept in their humidity domes?” and it’s all to do with roots. Clones should never be removed from their high humidity environment until they have roots. How long it takes a clone to root is another matter that will vary on your cutting, strain, and environment.
Generally, you need to leave clones for about a week at least before you can check whether they’ve started to root. You can do this by removing the humidity dome and leaving it off for a while, usually around 20 minutes to 2 hours. If there are any signs of wilting in this time period, then your clones likely haven’t rooted well enough to survive outside the humidity dome.
If they are wilting, spray the cuttings and put the dome back over the clones. If they’re not wilting, you can stop misting your cuttings and remove your humidity dome.
It’s a delicate balance to strike as misting your plants when they have roots can actually be harmful to your plant’s health. This test is one of the more foolproof ways of ensuring your plant can thrive outside its initial environment.
If you do remove your plant and the lower leaves begin to yellow or die, don’t worry. That’s your plant feeding off itself and moving nutrients from the old growth. Don’t remove it as it can harm your plant.
We realize we’ve skipped a few steps here and gone straight to the answer. You might be left wondering how to even clone using a humidity dome, or what a clone even is. We’ll cover all that below.
How to Clone a Cannabis Plant
Cloning isn’t a new concept. More commonly referred to as cuttings, gardeners have been doing it for years. In the right conditions, most plants can do this, it isn’t exclusive to cannabis plants.
The key to cloning cannabis plants is to provide the right nutrients, temperature, and humidity for the plant to thrive. This will allow it to form a new plant with the same genetic makeup as the plant it was cut from.
Taking a clone or cutting is simple. Start by cutting the leaf as close as possible to the stem. This makes sure you have plenty of room for roots to grow.
Drop the cutting into a cup of water to stop air from getting into the stem. Then prepare your starter or seedlings tray by moistening the soil.
When your tray is prepped, go back to your original cutting. Cut the base of the stem at a 45-degree angle. This will help by exposing more of the branch’s mass.
Dip each branch into cloning gel, roughly an inch above the 45-degree cut. Coat generously and then place into the previously prepared starting tray.
Growing Cannabis Clones
The reason humidity domes are recommended for clones is due to humidity. Clones or cuttings need a much higher humidity level than seedlings. Humidity domes make sure that clones get enough moisture to root successfully.
As we mentioned above, it will take around a week to 10 days for your clones to root. While your first day will obviously revolve around the cutting process, the rest of your week should look something like below.
Day 2: Remove the humidity dome and spray your clones with water. You should be doing this at least twice a day. Replace the dome back over your clones once they’re sprayed.
Day 3: Spray in the morning and at night. A good humidity dome will also have vents you will be able to open and you should do this now. This allows the moisture to escape slightly and stop the plant from growing mold.
Day 4: Leave your vents open and continue to spray twice daily. Hopefully, by this point, your clones should be more noticeably upright than the previous days.
Day 5: You’ll want to check your chosen soil method today to see how moist it is. If it’s dry to touch, add some more water to the bottom of your tray. This will encourage the roots of your clone to search down for nutrients.
Day 6: Close your vents, but continue to spray twice daily. This is because you want to promote extreme humidity to encourage root growth. If you’ve chosen a transparent growing medium, you should be able to see some roots by now.
Day 7: Continue spraying at least twice a day. Keep your vents closed and maintain high humidity.
Day 8 and 9: If you’ve chosen a transparent growing medium, you should be able to see roots on about 90 percent of your clones by now. Keep your vents closed and continue spraying daily. If your soil is dry, you can also add a mix of water and grow nutrients to your cloning tray.
Day 10: Remove the dome and do the check we suggested above. If your clones stay upright, transplant them to your next growing medium. If not, put them back under the humidity dome and continue the process.
Lighting for Cannabis Clones
There’s much debate about the right lighting for cannabis clones. Mostly revolving around red versus blue light and the various successes of either.
The main thing to remember is you don’t need intense lighting to grow clones. Generally, a fluorescent lighting system is enough. Too much light will actually hinder clone growth.
Generally, you should follow an 18-6 light schedule, or a 24-0 light schedule. Sometimes the latter can make maintaining a consistent temperature and humidity much easier.
Other Tips on Growing Clones
Besides the basics above, there’s plenty of other tips to help your clones thrive.
The first, and most obvious, is to take your clones from healthy plants. Taking your clone from an unhealthy plant is a recipe for disaster. Pick your best mother plant to take clones from.
Similarly, you want to choose the best cuttings from that plant. Choose healthy green branches with leaves with translucent veins. Ideally, the branch will have at least six nodes.
When you’re cutting, use a sharp blade to make clean angled cuts as we mentioned above. For strains that are particularly hard to clone, you can make the second angled cut under running water. This stops the stem from being exposed to the air and aids the capillary action.
You should also be using sterile equipment. Cannabis plants in general are prone to disease and mold, and clones even more so. You can minimize this by using sterile equipment during your cloning process.
We mentioned lighting above, but we’ll touch on it again. Clones can burn very easily and for this reason, you should avoid HID lights and use CFL grow lights or fluorescents. You can even place clones near a window and use indirect sunlight if you wish, just keep an eye on humidity and temperature.
You can also limit transpiration in your plant by cutting off half the leaflet on each cutting. This essentially decreases the amount of surface area that is able to transpire. It has a secondary benefit of reducing the risk of fungal infection if you’re using a humidity dome.
Our absolute best tip when it comes to cloning is to use a humidity dome. It makes the entire process much easier. It stops plants from drying out and limits the amount of transpiration the plant needs to do.
Cloning with Grobo
Grobo takes the guesswork out of growing with a humidity dome. With our Grobo Start, all you need are seeds and a larger Grobo unit.
Grobo is an automated grow box. We use the hydroponic technique of deep water culture to grow the plants. All users need to do is simply add their plant, pick a grow recipe from our app and the system does the rest. All you need to do is add water.
With Grobo, you can expect to grow around 2 to 3 ounces every 3 or four months. You can grow from seeds or clones. You can learn more about Grobo on our site or we have loads of educational videos on our YouTube channel.