Making a Cannabis Clone Box: Build a Simple Cloning Rack

By Rick Smith / January 12, 2021

Wooden cloning cabinet with humidity domes over trays of cannabis cuttings under light bars

Table of Contents

Quick answer: A cannabis clone box is a small, enclosed space that keeps fresh cuttings warm, humid and under gentle light while they root. You can build one from a cabinet, a closet shelf or a wire rack with a light on each shelf, clear domes over the trays, a hygrometer and a small fan for air. Keep the air at about 65 to 75°F and the humidity high, and vent the domes daily.

Some growers call it a weed cloning rack. Whatever the name, the goal is the same: a steady, clean space for the first one to three weeks of a cutting’s life. This guide sticks to the build itself. For taking the cuttings themselves, see our guide on how to make cannabis clones.

What a Cannabis Clone Box Needs to Do

A fresh cutting has no roots, so it cannot take up much water. Iowa State University Extension says decreasing water loss is important for success with stem cuttings, and that high humidity is essential for rooting. A clone box exists to hold that humidity steady while roots form.

It also has to keep the cuttings warm, give them gentle light and let in fresh air. Purdue Extension recommends keeping cuttings between 65°F and 75°F and avoiding excessive heat. It also says to place them in a bright area, but out of direct sunlight, so the leaves get the light they need without overheating. The box does the same job indoors, with lamps in place of a bright window.

Last of all, it has to stay clean. Purdue says to take cuttings only from healthy plants and to use clean tools and pots to prevent the spread of disease. A box with smooth, wipeable surfaces makes that easier.

Choosing a Cabinet, Shelf or Rack

Three common bases work well for a home cloning rack:

A cabinet or cupboard. Doors hold warmth and humidity in and block light from the room. Leave enough height on each shelf to lift trays in and out without hitting the light.
A wire shelving rack. Easy to set up, and each shelf can hold a light on the shelf above. Wrap it in reflective sheeting or a cover if the room is cool or dry.
A closet shelf. Good for a single tray. Use the shelf above to hang a light.

Pick a size that fits the number of cuttings you take at once. One or two standard propagation trays per shelf is plenty for most home growers. Avoid fibrous insulation inside the box. It is a humid space, and soft, absorbent materials can hold moisture and grow mold.

Parts List for a Clone Box Build

Part	What it does	Notes
Cabinet, shelf or rack	Holds everything	Smooth surfaces wipe clean
Reflective lining	Bounces light back onto trays	Mylar or white panels. Avoid fibrous insulation
One light per shelf	Gentle light for leaves	Low heat output, mounted above the tray
Propagation trays and clear domes	Hold cuttings and humidity	Domes with adjustable vents are handy
Rooting medium	Supports the cutting	Well drained, kept moist, not waterlogged
Hygrometer and thermometer	Shows humidity and temperature	Place one at tray height
Heat mat (optional)	Warms the rooting medium	Use with a thermostat
Small fan	Moves air around the box	Never blowing straight at cuttings
Exhaust fan (optional)	Removes heat from an enclosed cabinet	Mount high, where warm air collects
Timer	Switches lights on and off	Keeps the schedule steady

If you plan to warm the rooting medium, our guide to seedling heat mats for cannabis covers mat choice and placement. For how high to hang a light over young plants, see our guide to LED light distance for cannabis. Small fans and timers have their own guides on the site too.

How to Build a Cannabis Clone Box

Clean the space. Wipe the cabinet, shelves, trays and domes before you start. Missouri Extension says to use clean containers and cutting tools.
Line the inside. Fix reflective sheeting or white panels to the walls so light bounces back onto the trays instead of being absorbed.
Plan the shelves. Leave enough room on each shelf to slide a tray and dome in and out without touching the light above.
Mount one light per shelf. Fix it to the underside of the shelf above, so it sits over the center of the tray.
Add air movement. Place a small fan so it moves air around the box, not straight at the cuttings. In a closed cabinet, mount an exhaust fan high on the back wall, because warm air from the lights rises.
Run the power safely. Route cords away from water, use a power strip with a switch and keep plugs off the floor of the box.
Add the timer and meters. Put the lights on a timer, and set a hygrometer and thermometer at tray height.
Set up the trays. Fill trays or cells with moist, well drained rooting medium, and keep the clear domes ready.
Test run for a day. Run the box empty for 24 hours. Check that the air stays between 65°F and 75°F and that the humidity under a closed dome stays high.
Load the cuttings. Set the cuttings in the trays, cover them with the domes and start the routine below.

A Simple Shelf Layout

A three shelf rack or cabinet can be split into zones so each stage has its own space.

Top shelf: fresh cuttings. Domes closed, vents mostly shut, humidity highest. This is where cuttings spend their first days.
Middle shelf: cuttings with new roots. Domes vented more each day as cuttings harden off.
Bottom shelf: rooted plants waiting to move on. No domes. These plants are ready for bigger pots and more light.

Planning Space Near a Clone Box

Many growers keep the plants they take cuttings from in a separate space of their own, not inside the clone box. Those plants are bigger, need more light and more room, and would crowd the trays. Plan a spot nearby so you can take cuttings and move them straight into the box.

Clone Box Settings

The figures below come from Extension guides for rooting stem cuttings of houseplants and garden plants. They are good starting points for a cannabis clone box.

Setting	Target	Source
Air temperature	65 to 75°F, avoid excessive heat	Iowa State, Purdue
Rooting medium temperature	75 to 80°F with a heat mat	Iowa State
Humidity	High, under a bag or dome held off the leaves	Iowa State, Purdue
Light	Bright but not direct or harsh	Iowa State, Purdue
Fresh air	Open the cover at least once a day	Missouri
Cover off	After about 1 to 2 weeks, depending on the cutting	Missouri
Ready to pot up	Roots about 1 inch long	Iowa State

Iowa State also says not to seal the bag or dome tightly, so air can still exchange. Missouri Extension adds that if cuttings wilt after the cover comes off, put the cover back. The cuttings need more time in a humid space.

Daily Clone Box Routine

Check the meters. Read the temperature and humidity at tray height.
Vent the domes. Open each dome at least once a day for fresh air, as Missouri Extension advises.
Look at the leaves. Upright leaves are a good sign. Wilting means the humidity is too low or the box is too warm.
Check the medium. Keep it moist but not waterlogged. Purdue says rooting mix that stays waterlogged lacks air, and cuttings will rot rather than form roots.
Remove anything that rots. Take out dead or moldy cuttings right away, so problems do not spread.
Open vents a little more over time. As roots form, open the dome vents more each day before removing the dome.

Troubleshooting

Cuttings wilt under the dome. Humidity is too low or the box is too hot. Close the dome vents a little, check the air temperature and move the light up if leaves feel warm.

Mold or a musty smell under the dome. Too little fresh air or a medium that stays too wet. Vent the domes daily, increase air movement in the box and let the medium dry slightly between waterings.

Cuttings are slow to root in the box. Check that the air sits at 65 to 75°F and the medium is warm. Iowa State notes that too little light slows root formation. Some growers also use a rooting product, covered in our guide to rooting hormone for cannabis clones.

Cuttings turn yellow. Older leaves on a cutting often yellow as it uses stored reserves. Steady yellowing across many cuttings can mean too much water or too little light. Check the medium and the light.

The box runs too hot. Lights add heat, especially in a closed cabinet. Add or upgrade the exhaust, raise the lights or run the box in a cooler room. Purdue says to avoid excessive heat for cuttings.

Stems turn soft and dark at the base. The medium is too wet. Purdue says waterlogged rooting mix is devoid of air and cuttings will rot. Use a better drained medium next time.

Frequently Asked Questions

What is a cannabis clone box?

A cannabis clone box is an enclosed cabinet, shelf or rack that keeps fresh cuttings warm, humid and under gentle light while they form roots. It usually has a light on each shelf, clear domes over the trays, a hygrometer and a small fan. Iowa State Extension says high humidity is essential for rooting.

What humidity do cannabis clones need in a clone box?

High humidity, kept around the leaves with a clear dome or bag. Iowa State Extension says high humidity is essential for successful rooting, and not to seal the cover tightly so air can exchange. Missouri Extension says to open the cover at least once a day and remove it after about 1 to 2 weeks.

How much light does a cannabis clone box need?

Cuttings need gentle light, not strong light. Purdue Extension says to keep cuttings bright but out of direct sun so they do not overheat. Iowa State Extension notes that too much light can burn foliage under domes, while too little slows root formation. Its hours figure is for houseplant cuttings, so we do not apply it to cannabis.

Should a cannabis clone box have a separate mother plant area?

Usually yes. The plants you take cuttings from are larger, need stronger light and would crowd the trays. Many growers keep them in a separate space next to the clone box. That keeps the box humid and gentle for cuttings, while the larger plants get the light and room they need.

Is a weed cloning rack the same as a cannabis clone box?

Mostly, yes. Both names describe a space built to root cuttings. A cloning rack is usually an open shelving unit with a light on each shelf, while a clone box is often an enclosed cabinet. An enclosed box holds warmth and humidity more easily, while an open rack is quick to build and easy to reach.