Lahtelan Puutarha, a family-run greenhouse business in Finland, has relied on Grodan’s stone wool solution for more than 20 years. With this trusted partnership, they now produce clean, high-quality lettuce year-round — all while working more sustainably and efficiently.
When Juha, owner of Lahtelan, first considered changing his lettuce-growing substrate, it wasn’t because he wanted to follow trends or make radical shifts. It started in a familiar place — the old greenhouse at his parents’ home — where he noticed Grodan plugs being used for Chrysanthemum seedlings.
Back then, Juha’s lettuce cultivation relied on the traditional combination of plastic pots and peat. It was a routine he knew well, but it came with challenges: space requirements, time-consuming residue checks, and a lot of manual effort to separate peat from roots at harvest.
Switching to Grodan stone wool plugs seemed like a leap at first glance. But once Juha experienced the ease of harvest — simply cutting the plug from the lettuce crop without any residue checking — he saw the true value. The cost balanced out in the end, and the workload dropped significantly. As Juha puts it, “No more peat stuck to lettuce leaves — it was cleaner, simpler, and better all around.”
Discovering New Advantages
Juha’s transition to Grodan stone wool wasn’t without surprises. The real game-changer came with the flexibility of the sowing process. With Grodan plugs, Juha could sow directly into dry stone wool, store the prepared sowings in cooler conditions, and pause germination until needed. Germination was then started once the plugs were saturated with a nutrient solution at the correct EC. This meant no more daily sowing schedules or working weekends — while still maintaining an even, consistent crop rotation.
“This was transformational for our workflow,” Juha recalls. “It gave us freedom without sacrificing quality.”
The Importance of Details
Years of experience taught Juha the importance of small but crucial growing details. For example, he ensures that the top of the plug sits just slightly above the gutter — a simple adjustment that helps prevent stem rots and other root-zone diseases.
Switch to Clean – Anywhere, Anytime
For Juha, Grodan stone wool has proven that clean, efficient lettuce production is achievable — without compromise. Switching from peat to stone wool simplified workflows, reduced labor, reduced contamination risks, and gave his team more flexibility.
Grodan’s “Switch to clean” promise matches his reality: lettuce plants with impeccable hygiene, grown in a substrate that supports economic, high-quality cultivation. And with the ability to sow, store, and grow without being tied to a rigid schedule, Juha can truly cultivate anywhere, anytime.
A True Partnership
Lahtelan’s journey with Grodan is more than a customer story — it’s a collaboration. Over more than two decades, Grodan has supported Juha with tailored advice, technical know-how, and fine-tuned guidance. That’s what Grodan means by being a partner in precision growing: not just supplying substrate but helping growers optimize every phase.
Juha sums it up with a smile: “Stone wool makes growing lettuce cleaner and easier. Once you make the switch, you don’t want to go back.”
