Horticulture notes December 2008

Hydrangea macrophylla is a woody shrub whose showy blooms have been a familiar garden feature for many years. A hardy shrub native to Japan, it was first introduced to the U.K. in the early 1800’s. However, modern varieties of Hydrangea now enjoy renewed popularity as cut flowers for floral designs.  Their flower heads come in a range of colours depending on the variety grown, stage of cutting and how they are cultivated. They can be harvested at the ‘fresh’ stage for pink, blue or white flowers from May onwards.  They are also available later in the season at the ‘classic’ stage, as multicoloured heads.

Cut flower hydrangea is a high value crop but in this regard the growing conditions must be carefully managed, to maximize quality.  At the Horticulture Development Centre, Greenmount Campus, a number of Hydrangea varieties are evaluated for container-based production in a glasshouse environment. Cathal Ellis, Horticulture Technologist at CAFRE Greenmount Campus, is the project manager for this crop. Cathal commented “Our results so far show that a hydrangea crop can be harvested from May through to October. The flower head ranges from 15cm to 25cm in diameter, with a stem length of up to 90cm.  Flowers at ‘fresh’ stage have a vase life of at least two weeks and those cut at ‘classic’ stage last more than three weeks if dried”.

David Davidson, CAFRE’s Cut Flower Development Adviser, consults with Cathal on crop scheduling and standards for cut flower Hydrangea, with a view to adoption by local growers.  He explained some of the fundamentals for growing this crop commercially. “Hydrangea can only be produced to the required standards in glasshouses or possibly in multi-span polytunnels.  In early growth, we must maintain a minimum temperature of 13⁰C, hence the facility needs an efficient heating system.  Then, as the season progresses, there needs to be controlled ventilation of the structure.  Shading from strong sunlight is also beneficial.  It’s clear that the right facilities must be in place for real success with Hydrangea”.

The varieties used have been bred especially for this purpose.  The bloom colour responds strongly to the characteristics of the compost in which the plants grow and is also influenced by the liquid fertilizers applied.  There is obviously skill involved in meeting the standards for the market and David emphasized that these markets must be clearly identified before endeavouring to grow this crop.  Nevertheless, a single planting may give seven to ten years’ cropping, and each stem can command a relatively high price, so there is good potential from the initial investment.

The project received a welcome endorsement from the floristry sector earlier this year.  In July, the Royal Horticultural Society floristry competition at Tatton Park awarded Gold to a design using Hydrangea from CAFRE, Greenmount Campus, in the World Skills UK Intermediate Floristry final.

Any ornamentals growers who are considering cut flowers as an extension to their current product range should be planning now for the possibility of planting in spring 2009.  There are a number of varieties which are a suitable introduction to cut flower growing.  These include:

All can be brought into flower in a single season using simple polytunnel construction and some judicious preparation.  Again, the most critical factors for success are to find your market and to meet the needs of the customer with respect to quantity, specification and timing.

For further information on these enterprises, please email me your query and I will forward it to my colleagues David or Cathal.

Romaine Hodgen, a graduate of the National Certificate in Floristry at CAFRE Greenmount, pictured with her prizewinning arrangement at Tatton Park.