12 October 2020

In Pictures: Sowing the American Prairie

A behind the scenes look at the first sow of our new American Prairie at Wakehurst.

By Katie Avis-Riordan

Sowing prairie seed by hand

Our American Prairie is taking shape right before our eyes.

Spanning six acres, this conservation landscape sits centre stage in our wild botanic garden. 

Take a sneak peek at what we've been doing to create our new prairie at Wakehurst, including sowing the first seed and caring for live plants in our nursery.

Seed preparation

In September came the first sowing of our sweeping grassland.

The prairie seeds, many gathered on our seed collecting trip to North America, were stored in the drying room of our Millennium Seed Bank in optimum conditions.

These seeds, including prairie dropseed (Sporobolus heterolepis), were then retrieved in preparation for the sowing.

Seeds collected from the drying room in the Millennium Seed Bank for the American Prairie
Seeds collected from the drying room for the American Prairie, Jim Holden © RBG Kew
Close up of prairie dropseed (Sporobolus heterolepis)
Prairie dropseed (Sporobolus heterolepis), Jim Holden © RBG Kew

Our horticulture team checked the species to make sure the correct seeds were coming out of storage.

Jo Wenham in the Millennium Seed Bank checking list of species for the American Prairie
Checking species for the American Prairie, Jim Holden © RBG Kew

One of the zones of our new landscape is the South Central Tallgrass Prairie, which will showcase plants from this habitat in North America. 

To recreate this wild landscape here in our gardens, the various seeds to be sown had to be blended in the perfect ratio of the different plant species.

Mixed by hand, the seed blend was then put into large barrels for further mixing and transport.

Seeds of different species for the American Prairie
Seeds of different species for the American Prairie, Jim Holden © RBG Kew
Mixing the seeds of different species for the American Prairie in a large container
Mixing the seeds of different species for the American Prairie, Jim Holden © RBG Kew
Close up of American Prairie seed mixture
Prairie seed mixture, Jim Holden © RBG Kew

Soil scarification

The prairie ground was scarified to prepare the soil for sowing, and again afterwards to bury some of the seed.

This process, which breaks up the top level of the soil, can help encourage seed germination.

Scarifying the soil for the American Prairie at Wakehurst
Scarifying the soil for the American Prairie, Jim Holden © RBG Kew

Sowing the seed

Before sowing, the seed was mixed with horticultural sand to help create a smoother coverage.

A hopper was then used to sow the seed...  

Close up of prairie seed being mixed with horticultural sand
Prairie seed mixed with horticultural sand, Jim Holden © RBG Kew
Sowing American Prairie seed with a hopper
Sowing American Prairie seed with a hopper, Jim Holden © RBG Kew

...which was also done by hand.

Sowing by hand ensures an accurate finish, particularly near the edges of the landscape.

Sowing prairie seed by hand
Sowing prairie seed by hand, Jim Holden © RBG Kew
Sowing prairie seed by hand
Sowing prairie seed by hand, Jim Holden © RBG Kew

Once the seed was sown and after the second scarification, the seed beds were covered in a double layer of fleece.

This protects the germinating seeds from being eaten by birds, including our resident geese, and also traps a welcome layer of moisture to improve growing conditions.

This fleece has to remain in place for a few weeks.

Covering prairie seed beds in fleece at Wakehurst
Covering prairie seed beds in fleece at Wakehurst, Jim Holden © RBG Kew

In the nursery

Some of the seeds for the American Prairie are not being sown but are growing in our nursery and will be planted directly in the landscape at a later time. 

The reason that some plants are sown direct while others are raised in the glasshouse is to accelerate the establishment of harder-to-grow species and recreate the complexity of a mature prairie quicker.

To help speed up germination, the hard shell of the nursery plant seeds is chipped away, echoing the processes that naturally occur in the wild during winter.   

Tweezers and scalpels are the handy tools used to break the seed coating.

Close up of tweezers and scalpel chipping the hard coat of a seed to encourage germination
Preparing the American Prairie seed in the nursery, Jim Holden © RBG Kew

Once the seeds have germinated, they are ‘pricked out’ into plug trays to give them more space to develop.

Little bluestem (Schizachyrium scoparium), white false indigo (Baptisia alba) and rough blazing star (Liatris aspera) are some of the species currently growing in our nursery for the prairie.

Germinated little bluestem for the American Prairie in the nursery
Germinated little bluestem for the American Prairie, Jim Holden © RBG Kew
Germinated little bluestem for the American Prairie in the nursery
Germinated little bluestem for the American Prairie, Jim Holden © RBG Kew

Seedlings are sometimes put into growth chambers which create optimum light and temperature conditions for the plants to thrive.

Putting germinated seed into growth chambers in the nursery
Putting germinated seed into growth chambers in the nursery, Jim Holden © RBG Kew

The live plants are then cared for in our glasshouses with weeding and watering.

In spring, these plants will be ready to join the prairie landscape with the first live plant layer. 

Watch our animation to see how our American Prairie will transform

Caring for Sporobolus heterolepis in glasshouse at Wakehurst
Caring for Sporobolus heterolepis in glasshouse at Wakehurst, Jim Holden © RBG Kew
Yellow coneflower (Echinacea) in prairie

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