1 June 2017

Grass Garden’s annual trim

Every year, we cut the beautiful grasses down as spring approaches – but why? Find out why the whole of the Gardens outdoor team are needed for this annual ‘haircut’.

By India Pinnock

A record-breaking team effort 

There is often a misconception that winter is a quiet month in the Gardens. However, this is not true for the horticultural team who look after the Grass Garden, as February and March is when we carry out our vital annual maintenance work. 

The Grass Garden is in the north east corner of Kew, situated in between the Rock Garden and the Duke’s Garden. It is a spectacular part of the Gardens and garners admiring glances all year round.  

When a handful of people attempt to cut the Grass Garden down, it can take up to a week to complete and that doesn’t include weeding and dividing. So this year we put a call out for help from the whole Gardens team to get the job done quicker, while also boosting morale within our team (sometimes a big job can seem a little overwhelming).  

So on a Monday morning, around 20 horticulturists from across the Gardens armed with rakes, buckets and secateurs appeared as if by magic. We managed to get the job done in a record breaking two days. 

Winter beauty

Ornamental grasses are wonderful additions to any garden as they are highly decorative, easily maintained, and relatively pest and disease free. 

The Grass Garden provides great winter interest, especially on a crisp sunny morning when the frost adds a sparkle to the gold and auburn leaves and spent flowers. 

Every year, when the time comes to tackle the grass garden, I have a brief moment of sadness as I consider the impending removal of such wonderful texture and colour which provides interest during months when there is little else to see in the garden. 

 However, I quickly remember that all is not lost, as winter is coming to an end and before I know it spring will arrive bringing new growth, and the Grass Garden will be back in full swing.

Top tips for trimming grasses 

There are some key things to remember when cutting down grasses:  

  • Evergreen and semi-evergreen grasses, such as Stipa tenuissima, Festuca glauca and Chionochloa rubra, do not need to be cut back. 
  • Old flower stems should be removed and they may need to be lightly trimmed and combed through to remove any dead or scorched growth. However, if some of these grasses, such as Anemanthele lessoniana, have a lot of dead material they can be rejuvenated by reducing the height by one third to a half during April to June, when they are actively growing. Cortaderia selloana (pampas grass) is given a haircut and all the old flower stems removed.    
  • Deciduous grasses such as Calamagrostis, Miscanthus and Panicum can be cut back entirely to make way for new growth in the spring, when the temperature warms and the season gets going. We cut all of these grasses back to the same height which is around 3 to 4 inches (7 to 10cm) from the ground. 

The ideal time to cut grasses back also depends upon whether it’s a cool season grass (flowering in spring or autumn) or a warm season grass (flowering in summer). The cool season Calamagrostis x acutiflora ‘Karl Foerster’ should be cut back before growth starts in early spring. The warm season Miscanthus sinensis ‘Morning Light’ has culms (old stems) protecting the crown of the plant from frost damage, so should be cut back in spring after the worst of the winter weather has past. 

At Kew our seasonal work schedule and the sheer size of the Grass Garden results in some grasses being cut back slightly earlier than most. However, as Kew is more sheltered than many places in the UK – and with increasingly milder winters – this does not affect the health of the plants or the wonderful display that they put on year after year. 

At a glance it may seem that our work here is done. However, in the following few weeks, we will carry out any necessary dividing and weeding through the entire Grass Garden with a fine-tooth comb just in time for the start of spring.