Sowing and Varieties
Oilseed rape, from a sowing perspective, is characterised by its small seed, but also the crops ability to develop sufficient canopy from a relatively low plant count, provided the plants are evenly distributed and not excessively grazed by pigeons.
Optimum sowing date is from mid-August (North) to early- September (South), although later sow dates can still deliver good crops. These sowing dates can clash with harvest activities making rapid and labour-saving establishment systems attractive.
While for best establishment the small seed ideally needs a fine, firm seedbed with good moisture conservation and a shallow (<1.5cm) sowing depth, good crops can still develop from lower establishment rates achieved with less precise sowing systems.
Drill to a depth of 1.5 cm into a fine, firm, level seedbed from mid-August (north) up to early September (south). Good establishment is critical for high yields and helps the crop withstand pest (slug/pigeon) attack and weed competition.
Ideally, cultivation should be done when soil conditions are dry as rape does not like compaction. However, the seedbed should be rolled as the rape seed is small and needs good seed to soil contact for rapid germination and successful establishment.
Trials from Oak Park show that seeding rates should be 60 - 80 seeds/m2 (lower rates are for hybrids).
There are a number of different varieties that are available to grow and they are generally divided into three types;
Clearfield Hybrid – these varieties can be sprayed with a herbicide which control brassica weeds and are generally recognised by the letters CL in the name.
For more details of varieties that are available click of the DAFM recommended lists https://www.gov.ie/en/collection/68b24-crops/
WinterOilseedRapeVarieties2013 (236KB, PDF)
HGCA_2013-14 (25KB, PDF)