Lavender Plugs: 72-Cell vs 20-Cell, Potting Up & Field Planting

A lavender plug is a young rooted plant grown in an individual cell. It is small enough to ship and plant efficiently, but developed enough to give a grower a head start over seed. It is not a miniature finished plant, and it should not be judged by how enthusiastically it flowers in the shipping tray. Roots are the headline.

Great Lakes Lavender Farm offers two commercial tray formats for different finishing systems.

Great Lakes tray specifications

The 20-cell product is intentionally sold as 20 plants even though the carrier has 21 cells. This is not a farm-themed math puzzle; it is the product specification.

Which plug size should you buy?

Choose 72-cell plugs when:

• Unit economics and cultivar count matter.
• You have clean bench space, irrigation control and trained staff.
• You can pot up or establish smaller liners promptly.
• You want to trial several cultivars without buying larger finished plants.

Choose deep 20-cell plugs when:

• You want more developed roots at arrival.
• Hand planting and transplant durability matter.
• The finishing window is shorter.
• Your team has less tolerance for the moisture swings of a small cell.

For a home garden or a small landscape, 3-inch plugs, 4-inch pots or 1-gallon plants may be more forgiving. For spring bulk planting with mature roots, compare bare root. The cheapest unit is not the cheapest established plant if the production system is a mismatch.

Before delivery

Prepare a clean receiving area, labels, irrigation water and the next container or field site. Confirm that the cultivar, quantity and expected week match the production plan. Use Compare Cultivars for mature traits and Field Planner for final spacing.

If potting up, select a clean, porous commercial medium with rapid drainage. Lavender production media and field soil have different pH and fertility targets, so do not copy a field pH recommendation directly into a greenhouse feed program. Container production media for lavender is commonly kept around pH 5.8 to 6.2, while MSU describes a higher field-soil range for Michigan gardens. Test the actual media and follow the media manufacturer's guidance.

Receive plugs correctly

1. Open cartons immediately and remove trays from sleeves or stacking.
2. Confirm cultivar labels and count.
3. Photograph any shipping concern before altering the tray.
4. Check moisture at the top, middle and bottom of the root plug.
5. Check roots for a light, healthy color and active tips; investigate odor, mushiness or widespread collapse.
6. Move trays into bright, protected conditions with air movement.
7. Water only according to need, ensuring the tray drains completely.

Do not leave plugs in a dark carton while the team "gets to them tomorrow." Lavender has already traveled. It does not need a second vacation in a warehouse.

Acclimate before full exposure

Shipping changes light, airflow and temperature. Give plugs a short transition into full production conditions, especially if they arrive during bright heat or cold wind. Maintain high light without scorching newly unpacked foliage. Protect small cells from rapid drying.

Acclimation does not mean a week in dim shade. Gradually increase direct exposure while monitoring moisture and foliage. If planting outdoors, harden plugs to wind and sun before transplanting.

Pot up without burying the crown

Fill the new container with lightly moistened medium. Make a hole that accepts the root plug without crushing. Set the top of the plug level with the surrounding medium; keep the woody crown at the surface. Firm gently and water in thoroughly, then allow the medium to dry slightly before the next irrigation.

A small plug may benefit from a soft pinch after it is actively rooted and growing, depending on the cultivar and finish goal. Do not pinch a stressed arrival by reflex. First establish roots, light and moisture.

Pot sizes can include 3- to 4-inch retail containers or gallon pots. Great Lakes retail specifications use a roughly 3-inch root profile for its 3-inch plug, a fuller 4-inch pot and a 1-gallon plant in a roughly 6.25-inch-tall TEKU pot. Choose the finish by market date and desired retail presence.

Water small cells with precision

Small cells dry quickly at the edges of a tray while center cells may remain wet. Lift the tray, inspect roots and check multiple cells. Water early enough for foliage to dry before night. Provide drainage and airflow.

Common errors include:

• Treating every tray position as equally dry.
• Frequent light watering that wets foliage but misses the full root plug.
• Leaving trays standing in drainage water.
• Keeping media continuously saturated during cool weather.
• Fertilizing a weak root system instead of correcting moisture and temperature.

Lavender is a light feeder. Use a measured professional program appropriate to the water, medium and growth stage. More fertilizer does not turn Tuesday into Friday; it turns compact lavender into soft green paperwork.

Field transplanting

Transplant after roots hold the plug together, the plant is hardened to outdoor conditions and the site is workable. Small 72-cell plugs may be potted up first when weather, weeds or irrigation control make direct planting risky. Deep 20-cell plugs are often easier to direct plant.

Set the crown at grade, water the root zone, label the block and monitor closely through establishment. Use drip irrigation and protect plugs from weed competition. Space by mature cultivar width and equipment access, not by tray size.

Great Lakes live-plant shipping runs March 1 through May 31 and October 1 through November 30. Summer shipping is paused June 1 through September 30, though local pickup may remain available. Commercial growers should work backward from their target transplant date and the current Wholesale Hub lead time.

Troubleshooting

Plugs wilt soon after arrival

Check root-zone moisture, shipping heat or cold, broken roots and sudden light exposure. Water only if the plug is dry; do not drown heat-stressed roots.

Lower leaves yellow

Investigate chronic wetness, low light, cool saturated media and root health before feeding.

Growth is tall and soft

Increase light and airflow, verify spacing and reduce excessive nitrogen. Avoid dramatic correction on a stressed crop.

Plugs do not root into the new pot

Check crown depth, media temperature, moisture, salinity and root condition. A wet, cold container can stall lavender even when the top looks green.

Frequently asked questions

Can I plant 72-cell lavender plugs directly in a field?

Yes, when roots are developed, weather is favorable, weed competition is controlled and irrigation is precise. Potting up first can reduce risk in difficult conditions.

How long should I grow plugs before transplanting?

Use root development and weather, not a fixed number of weeks. The plug should hold together, show active growth and be hardened to outdoor conditions.

Why are 20 plants sold in a 21-cell tray?

That is the defined Great Lakes product configuration. Plan and price it as 20 saleable plants.

Do lavender plugs need fertilizer?

They need an appropriate measured program in soilless production, but lavender is a light feeder. Test media and water rather than feeding by appearance alone.

Keep exploring

• 72-Cell Lavender Plug Trays
• 20-Cell Deep Lavender Plug Trays
• Wholesale Hub
• Compare Cultivars
• Field Planner
• Lavender Farm Simulator
• Bare Root Lavender Guide
• Lavender Field Planting Guide

Sources

• Michigan State University Extension: Growing lavender in Michigan
• Royal Horticultural Society: Lavender guide