Grodan A-OK 1.5 in Starter Plugs Prefilled Tray | Case of 1,500 Plugs

Grodan A-OK Starter Plugs in a Prefilled 50-Cell Insert

This case holds 30 prefilled trays of Grodan A-OK 1.5 in stone wool starter plugs, 50 plugs to a tray and 1,500 plugs in all. Each plug measures 36 x 36 x 40 mm, about 1.4 x 1.4 x 1.6 in, with a tapered bottom. The plugs arrive loose and pre-cut, already seated in the insert, so there is no sheet to tear apart. The insert drops into a standard 10 x 20 propagation tray and fits under the usual humidity domes. A thumb slot molded into the insert lets you lift the whole tray out without squeezing plugs. Stone wool is spun from basalt rock, and it holds water and air together in a uniform, fibrous block. That uniformity means every cell wets and dries at close to the same rate. The plugs suit seeds and cuttings alike, and they are made to transplant straight into larger Grodan blocks. The full case weighs about 20.6 lb and comes in a carton roughly 20 x 24.5 x 20 in. With this many plugs on hand, a propagation room can run several full flats a week from one case.

Preparing a Rockwool Tray for Seeds and Cuttings

Before the first cutting goes in, the rockwool tray needs a proper soak. Grodan recommends a solution near pH 5.5 with an EC of about 1.5 mS/cm or higher. Submerge the plugs for a few minutes, at least until the bubbles stop rising. Then let them drain completely, since a waterlogged plug starves young roots of air. Weighing a few saturated trays is a quick way to confirm they all took on the same amount of solution. For clones, dip the cut stem in rooting gel or powder and press it into the center of each plug. For seeds, set one or two per plug just below the surface and keep the dome on until they break through. Bottom heat and steady humidity speed things along, while standing water in the tray does the opposite. Let the plugs lighten a little between waterings. Roots then chase moisture outward. Once white roots show through the sides, the plugs are ready for the next block. Lift them by the plug, not the stem, and set them into a pre-soaked block with a matching hole. Because nothing needs separating, one person can stick a full insert in minutes.

Key Features

• Prefilled 50-Cell Insert: Pre-cut loose plugs come seated in the insert, ready to soak and stick.
• 1.5 in A-OK Plugs: Plugs of 36 x 36 x 40 mm with a tapered bottom for seeds or cuttings.
• Fits Standard Trays: The insert sits in a standard propagation tray and under common humidity domes.
• Thumb Slot: Lift the full insert out of the tray without crushing plugs.
• Basalt Stone Wool: A uniform fiber structure holds water and air evenly in every cell.
• Case of 30 Trays: Enough plugs to run several full flats through a propagation room each week.

Technical Specifications