Spearmint 505
climate. It grows well in soil ranging from sandy loam to clay loam rich in organic
matter with a good drainage system. Areas that lie wet in winter will not perform
vigorously and the plant may die. Spearmint crop cannot tolerate highly acidic or
alkaline soils and performs well under near neutral pH (7.5). Spearmint crop initially
needs lower temperatures and later a mean temperature of 20^ ∞C–40 ∞C is suitable for
its main growth period. It is highly successful in humid areas of foothills and in
places which receive 100–110 cm of well distributed rainfall.
31.3.2 Land preparation and planting
Spearmint requires a fine seed bed. Soil should be ploughed and harrowed thoroughly
in order to achieve this. As spearmint is a perennial crop in most countries, pre-
planting weed control is imperative to the long-term viability of the crop. A well
planned fallow and weed eradication programme before planting is therefore, strongly
recommended. Spearmint is planted by means of underground parts called stolons,
aerial runners and plantlets. These planting materials are prepared by fresh nursery
planting of rooted whole plants or plantlets drawn from the old (mother) fields. The
planting materials in nursery are grown with a plant spacing of 30 cm ¥ 15 cm in
August. The nursery grown plants reproduce profuse stolons by the months of December
and January.
The ideal time for field planting of spearmint is the second fortnight of December
to January end. Regarding ideal time of planting a reference could be made here
about the work done by Singh et al. (1995) on M. spicata. A field experiment was
conducted by these authors for two years to study the effect of planting time on plant
growth, biomass yield, oil yield and quality of spearmint oil (M. spicata L.) in
Central Uttar Pradesh, India. Maximum biomass yield (275 Q/ha) and oil yield
(175.4 kg/ha) were obtained from the crop planted on December 30, which was due
to better crop growth in terms of plant height, leaf area index, dry matter accumulation
and oil content. The quality of oil essentially assessed by carvone content was higher
in November–December plantings, compared to the late plantings. Planting of spearmint
in the second half of December is recommended under the agro-climate conditions of
Central Uttar Pradesh, India.
Before planting, the stolons/runners may be treated with 0.2% solution of any
contact fungicide like Captan for two minutes. Stolons are planted in shallow furrows
(7–10 cm deep) spaced at 45 cm–60 cm apart. After planting the furrows are covered
with soil and followed by light irrigation. An approximate quantity of 3–5 quintals
of planting material (stolons/runners) is usually needed for raising one hectare of
plantation.
31.3.3 Nutrient management
The essential oil yield of spearmint largely depends upon its growth, especially of the
vegetative parts or foliage. To ensure better vegetative growth, application of sufficient
amounts of essential plant nutrients to the soil or directly to the plant is highly
desirable. Sufficient amounts of organic manures (FYM, vermi-compost, etc.) have
to be integrated with inorganic fertilizers to improve the crop productivity as well as
the health of soil. In this respect FYM (10–15 t/ha) or vermi-compost (5 t/ha) may be
applied to the soil before planting. The requirement for the inorganic fertilizer essentially
depends on the fertility status of the soil. For soils with high organic matter and