RedRock® Starter Block PRO w/ 42/40 Hole, 4"x4"x4" (Single)

Give rooted cuttings and young plants a stable 4-inch stone wool home

This single RedRock® Starter Block PRO is a 4" × 4" × 4" commercial-grade stone wool grow block with a 42/40 pre-drilled hole. It supports the move from starter plugs into a larger root zone for hydroponic, greenhouse, and controlled-environment grows.

Why growers choose it

• Consistent 4-inch format: The pre-cut square makes spacing and transplanting more repeatable.
• 42/40 hole: Sized for compatible starter plugs and propagation workflows.
• High-density stone wool: Helps support plants while holding water and nutrients around developing roots.
• Designed for dry-back: The fiber structure helps the block accept irrigation while allowing excess moisture to drain.
• Protected root zone: The fitted wrapper helps the block hold its shape during handling.

Specifications

• Quantity: 1 single block
• Size: 4" × 4" × 4" or 10 × 10 × 10 cm
• Hole: 42/40 pre-drilled opening
• Material: Stone wool

How to use

1. Keep the block dry until you are ready to prepare it.
2. Saturate it with the nutrient solution recommended for your crop, then allow it to drain gently.
3. Place a compatible rooted plug into the pre-drilled hole.
4. Set the block on a suitable slab or system and manage irrigation, nutrients, and dry-back for your growing environment.

Handle mineral wool carefully and follow your crop program and equipment instructions.