Related PPT: Establishment presentation, Plant basics; Related Unit: Establishing plants on a
green roof
Teaching guidance:
Establishment workshop
Purpose: To let the students get experience and knowledge on how to sow and
plant a green roof and give them insight on small scale gathering of sedum
cuttings.
Time: 3- 4 hours.
Material for seed establishment: folding rule, seeds, a scale, a bucket with sand,
working gloves,
Material for sedum cutting: folding rule, plastic bags, a scale, table space, hedgeclippers, working gloves, scissors
Material for establishing plug plants: folding rule, planting spade, plug plants,
buckets with water, working gloves, bricks, dead wood
Equipment: Location: Indoors and outdoors
Requirement: A site prepared for planting and sowing, possibility to gather
sedum cuttings.
Instruction
Before this workshop takes place, hold the lecture about Establishment. This workshop can be
done together with The Nomenclature Workshop since they go a bit hand in hand. If the
students lack knowledge of plants, this workshop gives a nice introduction on how to handle
green roof plants.
For seed spreading: Start with measuring the area that are going to be sown. Recommended
amount is 4-10 grams/m2 (explained in the Establishment lecture). For a very dry climate opt
for the higher amount, if irrigated the lower amount is enough. Gather the seeds (collected
and/or bought) and measure the amount needed and mix together with sand in a bucket. The
sand should be dry to make the spreading easier. It is better to have too much sand instead of
too little, at least 2 litres. Mix well together. When spreading the sand-and-seed mix make
sure the whole area is covered.
Note: If seeds and plug plants are being spread and planted on the same site, 2 grams of
seeds/m2 is enough.
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Related PPT: Establishment presentation, Plant basics; Related Unit: Establishing plants on a
green roof
Gathering and spreading sedum cuttings: Measure the area where the sedum cuttings will be
spread. Recommendations 50- 75 grams of cuttings/m2 (also explained in Establishment
lecture), better to opt for 75 grams/ m2. Let the students gather sedum cutting by hand, with
scissors or hedge-clippers and store the cuttings in bags. It is very effective to use hedgeclippers, however you risk getting lots of sedum flowers and too long respectively too short
cuttings. The cuttings should be about 4-5 cm long and only the vegetative parts, not
blossoming stems. The students should also gather a good mix of different sedum species, not
only Sedum album.
When enough cuttings are gathered, measure up 1 m2 on a table and spread out 75 grams of
sedum evenly over the table. This illustrates how seemingly a large amount of cuttings looks
when being widespread over a small area, it is actually perceived as quite little.
Note: Sedum are drought tolerant and can be stored in a plastic bag for a few days. The
sedum cuttings can be saved for later, for example for the green roof installation.
Planting plug plants: Bring the materials needed to the area prepared for planting. The most
common mistake is that the plant is planted too shallow, the plant should be below the
surface of the soil, otherwise the roots are exposed. There is also a problem with planting too
deeply but this is not often the case when handling perennials and biennials.
Prior to planting, soak the plug plants in a bucket filled with water. Make sure that all of the
soil surrounding the roots are wet and heavily moist. By doing this, the roots have a good
amount of plant available water if it is not possible to irrigate the plants during the
establishment phase or if a rainfall event does not occur within the following days.
When digging with a planting spade be very careful not to harm the roof. Harming the root
barrier or the water proofed membrane is NOT desirable. Emphasize that working with tools
on a green roof require cautiousness.
With a ruler or folding rule the students can measure their prepared planting holes to make
sure they are deep enough, plant the plugs and fill the gaps with substrate. With a light
pressure, press the plant into the soil using your fingers. If the plant has developed a lot of
roots it is beneficial if the roots are ”loosened” and a bit separated from each other.
The recommendations are that if the green roof is being both planted and sown, 5-10 plugs
per m2 is sufficient. Otherwise opt for 10-15 plug plants/m2 if possible. To create a varied
planted area mix different species together. To optimize biodiversity, place out for example
logs, stones and bricks. If there are shallow parts on the green roof sedum cuttings can be
spread out. For a fast vegetation cover sow annuals together with the planted perennials.
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