Greenhouse Updates: Apr 14, 2015

Handling Plugs and Transplanting Tips
April 14, 2015

Here are some tips for handling plugs, media and tips for transplanting.

Handling Plugs:

Upon arrival, open and unpack the boxes immediately and check the physical condition of the plants. Inspect plants for root and foliar diseases and for insects and mites. Report any damage or discrepancies immediately to your supplier (most companies want to hear within 24 hours). Take a picture if there is a problem!

Place plug trays on benches and water thoroughly with plain water (no fertilizer); be sure that plugs on the edges of the trays are thoroughly watered. Plugs can dry out quickly due to the small volume of growing medium; check the trays 2 or 3 times daily for watering. After the initial watering, apply a general-purpose fertilizer (such as 20-10-20) at 50 to 60 ppm of nitrogen at every other watering. Allow plants to acclimate to the greenhouse conditions for 24 to 48 hours before transplanting.

Transplanting to a finishing container:

Water the plug trays thoroughly 2 to 3 hours before transplanting to aid in removing the plugs from the trays. Prepare your cell packs or pots by filling them with pre-moistened growing medium and pre-dibbled holes for the plugs. It is best to moisten, then mix and then allowed to set overnight prior to use. If that is not possible, waiting at least a couple of hours after adding the water will help the hydration process.

Lightly fill containers and brush off excess. Never stack pre-filled containers so they are nested. The media should not be packed down, tamped down, or the filled pots tapped down on the bench several times. Always try to preserve the air space or porosity to insure healthy root growth.

Sort out weak plants when transplanting so similar sized plants are transplanted together. Make a nursery for plants that need extra time to develop more roots. Place these in a warmer area with bottom heat and run them a little drier.

Train transplanters:

For uniform, healthy plants later, take special care during transplanting to handle plants gently and avoid planting too deep. Stems of tender seedlings can be easily injured when workers grasp or "pinch" the stems too tight. This often leads to stem cankers causing plants to wilt and die. Plant plugs at the same depth as the original plug. Some transplants may have elongated stems and it is tempting to "bury" the stem. Resist the temptation, except for more adaptable tomato plants.

Rooted cuttings from different wholesale suppliers may contain a variety of growing media. Adjust watering habits accordingly

For information on handling growing media, see the fact sheet:
"Greenhouse Substrates and Fertilization (PDF)", by Douglas A. Bailey, William C. Fonteno, and Paul V. Nelson Dept. of Horticultural Science, NCSU

Tina Smith, UMass Extension and Leanne Pundt, UConn Cooperative Extension