Fall Fertilization to Help Turfgrass Withstand Winter
Fall fertilization with DUO: the fertilizer for preparing turfgrass for winter dormancy
DUO 18-0-15 + 2 Mg is the professional turf fertilizer Green Europe Comagricola recommends to landscape professionals for feeding turfgrass before winter dormancy. Developed on agronomic principles, it combines nitrogen sources with different availability patterns, potassium and magnesium to deliver an immediate response and sustained nutrition.
Its role in fall maintenance is to support turfgrass as winter approaches, sustaining ongoing physiological activity and the buildup of plant reserves. The formulation addresses a specific stage: growth slows, while the turf still needs to maintain its physiological functions.
What happens to turfgrass before winter dormancy?
As days shorten and temperatures fall, cool-season grasses gradually reduce shoot growth and begin to acclimate to cold conditions. During this transition, tissue water balance changes, along with the concentration of cellular solutes, including sugars and potassium ions.
Cool-season turfgrasses can enter a state of semi-dormancy, with shoot growth slowing before root activity declines. The extent of this slowdown depends on species and climate. DUO supports the turf during this transition, while the plant is still able to use nutrients.
Pre-winter fertilization takes place within this physiological window, before nutrient uptake stops. A well-timed nitrogen application supports leaf tissue that remains photosynthetically active and contributes to the management program for building plant reserves.
DUO 18-0-15 + 2 Mg: nutrient composition
DUO is a phosphorus-free formulation that supplies nitrogen and potassium alongside magnesium:
| Nutrient | Nutrient content |
|---|---|
| N | 18% |
| Nitrate nitrogen | 3% |
| Ammoniacal nitrogen | 9.5% |
| Controlled-release nitrogen | 5.5% |
| K₂O | 15% |
| MgO | 2% |
The percentages of the individual nitrogen forms refer to the product and add up to 18% total nitrogen. Potassium and magnesium contents are expressed conventionally as K₂O and MgO.
Nitrogen availability: an immediate response and sustained nutrition
The nitrate fraction is readily available for root uptake. Ammoniacal nitrogen and the methylene urea component complete the nitrogen supply, extending the formulation’s effect over time.
This combination supports the turf during the fall transition. Initial availability and subsequent release operate on different timescales: the release rate of the longer-lasting component remains influenced by soil conditions, including temperature and biological activity.
The role of potassium in preparing turfgrass for cold conditions
In DUO, potassium is supplied from potassium nitrate. It plays a key role in water management within the plant, contributing to osmotic regulation, maintenance of cell turgor and stomatal function.
Potassium also participates in enzyme activation and processes associated with sugar metabolism. These functions are relevant during cold acclimation, when the plant adjusts the balance between water and solutes in its tissues.
This is the agronomic role of potassium in pre-dormancy fertilization: supporting the physiological processes involved in the plant’s response to winter temperature and water stress.
Magnesium: supporting photosynthetic function
Magnesium is the central atom of the chlorophyll molecule and is involved in the activation of numerous enzymes. Its inclusion in the formulation complements the nutritional support provided to tissues that remain active as available light decreases.
Why choose DUO before winter dormancy?
DUO brings together an initial response, a sustained nitrogen supply and potassium nutrition. These three components work within the same maintenance strategy to support the transition from fall growth to the winter slowdown, with a focus on turf quality and plant physiology.
The phosphorus-free formulation focuses the application on nitrogen, potassium and complementary nutrients. Its use therefore concerns maintenance feeding of established turf; any fertilization required for a new seeding belongs to a separate establishment program.
When and how to apply DUO to turfgrass
Apply before prolonged cold weather, while the turf is still able to take up nutrients. This guidance primarily concerns cool-season grasses: nitrogen management for warm-season grasses entering dormancy follows different principles.
Apply DUO at 30 g/m², equivalent to 3 kg per 100 m². It provides nutrition for approximately 60–70 days, with duration influenced by soil and environmental conditions.
Apply evenly using calibrated equipment and follow the instructions on the packaging. Avoid applications to frozen or waterlogged soil, or under conditions that favor runoff.
Download the DUO technical data sheet
Consult the technical data sheet for the formulation and product characteristics. Contact Green Europe Comagricola for supply inquiries and advice on incorporating DUO into a professional turf maintenance program.
↓ Download the DUO technical data sheet
FAQ – DUO and Pre-Winter Turf Fertilization
Why is DUO suitable before winter dormancy?
DUO combines nitrogen sources with different availability patterns and potassium to support the fall-to-winter transition. It helps prepare the turf for semi-dormancy by supporting ongoing physiological activity and the buildup of plant reserves.
What does potassium do in turfgrass?
Potassium contributes to osmotic regulation, maintenance of cell turgor and stomatal function. These processes support plant water balance and the response to environmental stress.
Does DUO provide an immediate or a prolonged effect?
DUO combines both. The nitrate fraction is readily available, while methylene urea contributes to the prolonged effect. The release rate also depends on soil conditions.
When should DUO be applied for winter preparation?
Apply DUO in October and November, before prolonged cold weather and while the turf can still take up nutrients. This guidance primarily concerns cool-season turfgrass.
What is the DUO application rate for turfgrass?
Apply DUO at 30 g/m², equivalent to 3 kg per 100 m². Follow the instructions on the packaging and apply evenly using calibrated equipment.
