Open Heart Cos

One of the most popular lettuces in the world, growing and packing cos is not without its challenges

Popular but challenging

Cos has a crisp, sweet flavour, and a nice contrast of leaf colour. However, the crop is susceptible to tipburn, and cut leaves discolour quicker than other lettuces. Open Heart Cos from Rijk Zwaan provides solutions to these challenges.

Grower friendly

Open Heart Cos are slow to close and suffer less tipburn than traditional varieties, giving them long field holding ability and a wide harvest window.


Almost 100% of cos lettuce leaves are cut. Traditional varieties have large midribs: when cut the rib can crush, and the hollow cavity is exposed to oxidation. Open Heart Cos have a small solid rib which doesn’t crush, meaning less oxidation.

Efficiency in practice

The uniform slender leaves mean the majority of leaves are usable, where traditional varieties have wide leaves that produce “batwings” when cut. The upright plant habit also means Open Heart Cos are suitable for mechanical harvesting.

Open heart cos varieties

More information on Open Heart Cos