Horticulture notes August 2007

Technology staff at CAFRE, Greenmount Campus have investigated a number of production techniques for ornamental plants and cut flowers. Their findings can assist nursery stock and cut flower businesses to improve the quality and marketability of crops.

Some woody ornamentals are slow to establish with conventional seed or cuttings propagation. The method of ‘air root pruning’ uses aerated containers and open-textured compost in place of normal nursery materials.  This technique increases the effective root mass in some high value species for example, Eucalyptus, Pine.

In 2006, a Greenmount Campus trial compared two commercial ‘air pruning’ propagation modules, the Elle pot and the forestry pellet, with traditional propagation cells. Teresa Maguire, Ornamental Crops Technician, explained their results. “For the evergreen shrub Eleaegnus xebbingei, we determined that air-pruning leads to a more fibrous root system.  This was associated with better branching and faster, taller growth. The advantage to growers is clear. Where larger pot sizes with this same ‘air pruning’ influence are used, this advantage also carries on through the production cycle”.

Adopting this production technique means larger shrubs may be produced in a significantly shorter time. It could also eliminate a potting stage from the nursery cycle, thus reducing labour and material costs.

Related work with seed-raised trees such as oak showed that they transplant very successfully.  ven five years after planting into the landscape, the ‘air-pruned’ oak trees had greater height, girth and mass than their conventional counterparts. Investigations are continuing at CAFRE to evaluate other seed- and cuttings-raised species.

Lilies are a beautiful addition to any flower arrangement. They are also a useful cut flower crop for those Northern Ireland growers who produced and marketed lilies to florists and wholesalers during 2006, as a result of technology demonstrated through Greenmount Campus. Feedback from wholesalers and florists thus far has been very positive.

Locally, the normal season for growing Oriental lilies is from late June to mid October. The typical production length for oriental lilies during this period is 11 to 15 weeks. This year’s trial work on extending production season saw high quality blooms produced under polythene, from late October until mid-February 2007. This was achieved by providing supplementary light and a minimum temperature of 6 Centigrade throughout winter. Not surprisingly, for these ‘out-of-season’ lilies the total time to crop is longer (at up to 21 weeks). In terms of energy use, the supplementary light and heat needed is difficult to justify, unless reflected in the price obtained.

Ongoing work will concentrate on answering two questions:

Further information on production of oriental lilies and other cut flower crops is available through your local technology or business development adviser.

Growers may be eligible to reclaim the excise duty on heavy (hydrocarbon) oil used for heating or soil sterilising.  If you produce horticultural produce for sale, such as fruit, mushrooms, vegetables (except main crop potatoes) flowers and shrubs, you can apply for duty relief from HM Revenue and Customs.  This applies to fuel oil and gas oil that is used to heat any building or structure associated with the production, or even used to heat or sterilise soil and growing media.

There is a minimum amount of £50 duty for any single claim and you must provide proof of purchase, with detail of quantity, supplier and use. Your claim should be made within 3 months of end of fuel use.