Cultivars of six leaf herb species were grown during 1999-2000 at South Finland (Piikkiö, 60° N, 23 ´E) and North Finland (Ruukki, 64° N, 41 E). The plants were propagated by seedlings, grown in black plastic mulch, fertilized by 20 t/ha compost. Growth, fresh and dry leaf yield, essential oil content, and composition were studied. The yields obtained from the southern growing site were generally higher by 10-40 % than those from the site 500 km further North. The shorter growing season affected the biomass production, but did not strongly influence the essential oil content and composition which were similar to other European results. The yield differences were very high in the case of Greek oregano and marjoram, but savory and dragonhead showed a better tolerance to the cooler climatic conditions and the yield differences were much smaller. Sage and thyme can be only grown in Finland as annuals and their yields were almost identical from both sites. Using bred cultivars, sufficient quantities of high quality raw material can be produced under Nordic conditions.

The study aimed to establish whether a high onion yield and good storage performance could be obtained with low fertilisation rates if irrigation was applied when necessary. Two-year experiments investigated the effects of three NPK fertiliser levels (N 50, 100, 125/150 kg/ha), with and without irrigation, on yield, advancement of maturity, storage losses and shelf life. High fertilisation advanced maturity but irrigation had no effect. High fertilisation increased yield only in 1996 (5B7%), but irrigation increased the yield noticeably: by 33.5% in 1995 and 8.5% in 1996. There was no interaction between fertilisation and irrigation. The low fertilisation optimum is attributed to the mineralisation of soil nitrogen, as the soil was rich in organic matter. At the low fertilisation level, plants took up twice as much nitrogen as present in the fertiliser, and with increased fertilisation the nitrogen uptake increased markedly. The foliage nitrogen content was low, evidently as a result of late harvesting. Treatments had only a minor effect on the storage performance and shelf life of onions. The results suggest that fertilisation rates could be reduced in onion production. Irrigation during warm and dry periods is essential to achieve the maximum yield potential and does not impair the storage quality of onions.;

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The effect of decreased nitrogen rates (90, 60 and 30 kg N/ha) with and without irrigation on celery yield quantity and internal quality were studied in field experiments in 1993 and 1994. The decreased nitrogen rates reduced yields in both years. In the dry and warm conditions of 1994 nitrogen x irrigation interaction was clearly observed; irrigation increased yield more at higher nitrogen rates than at lower nitrogen rates. In the rainy conditions of 1993 irrigation did not effect the yield level. On the other hand, in both years, decreased nitrogen rates increased dry matter, vitamin C and dietary fiber contents, and nitrogen had a minor effect on total sugar content. In 1994 alpha- and beta carotene and thiamin were also analyzed but nitrogen had no effect on them. Irrigation increased dry matter and total sugar contents at the two lowest nitrogen rates in 1994, but decreased vitamin C contents in both years. There was also slight evidence that irrigation might decrease alpha- and beta-carotene and thiamin contents.