Wetting rockwool slabs

  • After placing the dripper-sticks into the rockwool slabs you can start to fill up the slabs with the ‘wetting recipe’. A 100x20x7, 5cm slab needs at least 15 liter solution to get full saturation to the top. Give an extra amount of feed solution for flushing the slabs just before planting. This is important to get the right wetness, EC and pH at the planting holes just before planting.


  • Use disinfected boxes for the transport of young plants.
  • After the slabs reaches the right temperature the planting can start. Place the rockwool blocks directly at the planting hole (cucumber, sweet pepper, gerbera and roses) or beside the planting hole (tomato) and place the dripper-sticks into the blocks.
  • In a winter period tomatoes can be placed beside the planting hole for few days or week(s) to get the right generative balance for flowering of the first truss. After this period the plants can be placed at the planting hole to root in into the rockwool slab.
  • In winter period a 2-3 cm vertical drain-hole can be cut at the lowest point of the slab at the side of the drain gutter just before planting. Do this careful without damage of the ground cover foil.
  • By planting in summer time and hot climate conditions it’s recommendable to make the drain holes a couple of days after planting. Make then first one drain hole per slab in the mid level and approximately one week after planting a drain hole at the bottom level.
  • In case the soil is not properly leveled make then two or three drain holes to avoid a free water level at some places inside the rockwool slab. Make then at both ends of the slab a drain hole at the bottom and by very bad leveling of the soil also a hole in the middle of the slab at bottom level.
  • Do the planting one valve after another and start irrigation every time directly after a valve area is planted. This is important by planting under hot summer conditions.

    Irrigation after planting

  • Irrigate a few times per day (4 to 5 times) during the first days after planting.
  • As soon as roots developed 3 to 4 cm into the rockwool slab, then the irrigation can be adjust to the daily needed drain.

    Irrigation control in relation with drain measurements

  • Water uptake is depending to radiation, heating, plant size and plant condition.
  • A great help to determine the irrigation amount and irrigation frequency is to measure the daily drain amount.
  • Create a reliable drain measuring station per valve area.
  • Make a registration from drain quantity, EC and pH value
  • Ask HORTICENTAR for the detailed Water Management Form !
  • Keep in summer time about 30-40% drain and in winter time 15-30% drain. Exact drain amount is depending on water quality, weather conditions, plant condition, etc.
    The Balkan Greenhouse team wishes you good results with growing on rockwool.