Multi-species silage mix selection tips (June 26)

Silage quality starts with careful grass species selection. Ley longevity, yield and quality are all important factors to consider when deciding which variety makes the cut.

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When selecting grass and legumes for multi-cut silage leys, one of the first considerations is how long the ley is expected to persist. And yield and forage quality are equally important, according to Germinal’s William Fleming.

“Producers should aim for a tight heading date range of about seven days,” he told delegates during a recent Germinal webinar. “This provides flexibility for weather windows and contractor availability.”

He also advised using a 50:50 mix of tetraploids and diploid varieties. The latter have two sets of chromosomes per cell and are typically 2% higher in dry matter. Tetraploids have four sets of chromosomes and produce larger seeds. These varieties also establish more quickly and, therefore, compete better with existing grass.

“Having a balance is important,” stressed Mr Fleming. “Diploids provide good ground cover to prevent the ingress of weeds, while tetraploids are higher yielding.”

He also urged producers to select varieties from 2026’s Recommended Grass and Clover List. To make the list, which is updated annually in late spring, grasses and clovers must undergo rigorous independent testing under UK conditions and meet parameters for yield, persistency, quality and disease resistance.

“Using varieties that fail to make the list carries risks because they may not have been tested under UK growing conditions,” he explained. “‘Older’ varieties that have fallen off the list will have been superseded by newer, better-performing varieties in terms of yield and quality, and their return on investment will be lower.”

When selecting varieties for multi-cut systems, he said that consistency across the season is preferable. “Producers require good spring, summer and autumn growth to create a balanced mix that will perform all season long for multi-cut systems, as cutting typically takes place every four-to-six weeks from April or May.”

Persistent species

The main grass species used in silage mixes are perennial, hybrid and Italian ryegrasses (see Table 1).

Perennial ryegrass is the most persistent of all these grasses, typically remaining in the ley for between seven and eight years. It is quick to establish, delivers good early-season growth and maintains consistent quality, making it well-suited to multi-cut silage making systems.

“It can also be grazed later in the season if silage clamps are full or producers want take on tack sheep. This is important given there are very few fields in the UK that are silage only,” said Mr Fleming.

Hybrid ryegrass, a cross between perennial and Italian, is rapid to establish and produces high yields, but has a shorter lifespan compared to perennial species of between three and four years.

Italian ryegrass is the fastest to establish because it grows at lower soil temperatures, from 3°C, compared to perennials at 6°C. But it can be the most difficult of the three grasses to manage.

“A large area of Italian ryegrass was sown in the UK in autumn 2025 following the dry summer, as producers looked for ways to mitigate forage deficits,” he said. “But because it is a short-term grass, it wants to reproduce to continue its lifespan and mid-season it runs to seed. This makes it difficult to maintain optimum quality across all cuts, which is ideally what we want when operating a multi-cut system.”

Ultimately, species selection will depend on the dairy system and crop-rotation length.

However, perennial ryegrass will typically provide the most consistent forage quality throughout the season, according to Mr Fleming.

Cutting sward: multi-species leys should suit silage-making system

Reseeding costs

“There is also an argument for moving towards longer-term leys to reduce reseeding costs and improve soil health,” he noted.

Some producers are incorporating more diverse species, such as festulolium and fescues, to improve drought tolerance. But he warned delegates that this comes with trade-offs.

“These species tend to have poorer digestibility, which needs to be weighed up in terms of their impact on milk production and bought-in feed costs. They can also be more difficult to manage under frequent cutting regimes, because they require longer rest periods.

“For higher output indoor herds, resilience may need to be built into the system by cutting more grass or building buffers of forage stocks rather than adding complexity by using multi-species swards.”