🍀 Norcen

What it looks like

Norcen is the upright one of the family: a semi-erect to erect trefoil that stands tall enough to cut cleanly for hay, with leafy, multi-branched stems rather than the fine, sprawling stems of the prostrate grazing types. The flowers are the same bright yellow pea blossoms, the leaves the same deceptive five posing as three, but the silhouette is a hay plant’s silhouette — a stand you can mow, windrow, and bale without crawling after it. See the bird’s-foot trefoil species guide for the full species portrait.

Why this variety

Norcen comes from the North Central states breeding effort, and the North Central forage reference rates it plainly: semi-erect to erect habit, high winterhardiness, good yields, maturing midway between Viking (the earliest) and Empire (the latest). A state extension bulletin adds two more selling points: better seedling vigor than Empire, and a high ranking in crude protein with digestible dry matter on par with other varieties. It became the most widely grown trefoil in northern Michigan, which is the kind of adoption that says more than any trial table: farmers replant what survives their winters.

One honest wrinkle: references disagree slightly on exactly how Norcen’s winterhardiness stacks up against Empire’s — the North Central table rates it high, while another bulletin phrases it as less hardy than Empire. All of them agree it is a genuinely winter-hardy northern variety, so the disagreement is about the podium order, not about whether it belongs on the podium. Class it as a European-type trefoil: upright, suited to hay and haylage as well as grazing, where the prostrate Empire types are grazing-only specialists.

How to grow

Bird’s-foot trefoil seed is small and its seedlings are unhurried, so establishment is the whole game. Sow in spring or fall at about a quarter inch deep, spacing plants about 6 inches apart in a garden bed (field seedings run 8 to 10 pounds of seed per acre in monoculture), and keep the seedbed moist until the plants are up and running. Inoculate the seed with the right trefoil rhizobium if trefoil has never grown in that soil before — the nitrogen-fixing nodules do not appear by wishful thinking, and an uninoculated stand is a hungry stand. Trefoil reaches full size in one to two years, so do not judge it by its first summer. It is famously uncompetitive as a seedling, which is why forage references pair it with a gentle companion grass rather than an aggressive one: a small grain or a mild grass nurses it along, while a thug grass simply eats its lunch.

Give it full sun and well-drained soil, and it tolerates a remarkable range of abuse after that: light sandy, medium loamy, and heavy clay soils alike, nutritionally poor ground where fussier legumes sulk, soils down at pH 5.5 where alfalfa would demand lime first and ask questions later, and short wet spells that drown other forages. It prefers moist soil but tolerates dry, droughty ground once established.

For Norcen specifically, play to the hay habit: sow it where you can get a mower over it, whether alone or with a mild companion grass, and take the first cut at early bloom for the best balance of yield and quality. Its better-than-Empire seedling vigor helps at establishment, but ‘better’ is not ‘fast’ — trefoil seedlings are still unhurried by any standard, so the clean seedbed and gentle companion grass still matter. Because it matures midway between Viking and Empire, it fits a two-cut system without the rush of the earliest varieties or the wait of the latest.

Water & feeding

Keep the seedbed moist through establishment; after that, trefoil is a moderate drinker that tolerates dry spells better than its lush looks suggest, thanks to a taproot with many lateral branches running mostly through the upper 15 inches of soil. It does not want a swamp — persistent waterlogging invites crown and root rots, the quiet killers of legume stands — but it handles short wet spells and poorly drained corners far better than alfalfa, which is exactly why it became the forage of marginal land.

Feeding is mostly a matter of not overdoing it. As a legume, trefoil fixes its own nitrogen through rhizobium nodules on its roots, so nitrogen fertilizer is money spent on a problem the plant already solved. What it does appreciate is phosphorus and potassium kept up to soil-test levels, especially on the poor, acid soils it is usually asked to redeem. Lime only if a soil test says so: trefoil tolerates pH 5.5, but it will not complain about a nudge toward neutral either.

Common problems

Slow establishment is the classic trefoil complaint, and it is really a weed complaint in disguise. Seedlings that take their time are seedlings that weeds overtop, so a clean seedbed and a non-bullying companion grass matter more than any spray. Mowing weeds above the young trefoil — clipping the competition without scalping the crop — is the oldest fix and still a good one.

Overgrazing is the second trap. Trefoil persists by reseeding itself, and a stand grazed or mown to the dirt with no rest never gets to set that seed. Forage references give grazed trefoil 4 to 6 weeks of rest between grazings, and that rest is not laziness, it is the stand’s retirement plan. Cross-pollination is a third, subtler issue: because trefoil outcrosses freely, seed saved from an old stand is rarely pure variety anymore, so a stand that starts as one named variety gradually becomes a neighborhood mix. That is fine for a pasture, but it means variety purity is a starting condition, not a permanent one.

One thing trefoil does not do is bloat livestock. Its condensed tannins bind plant protein in the rumen and keep the foam down, which is why it can be grazed as a pure stand where alfalfa and clover cannot — a genuine superpower, and the reason graziers forgive its slow start.

Harvest

Graze it or cut it for hay, and either way the rule is the same: take a cutting, then let it recover. Trefoil holds its feed quality late into maturity better than many legumes because of its high leaf-to-stem ratio, so a slightly late first cut is not the disaster it is with some forages. Let some plants flower and set seed each year — those bird’s-foot pods are the next generation of the stand, and a stand allowed to reseed is a stand that outlives its planter’s patience. Mowing after grazing keeps the sward even and stops the ungrazed patches from going woody and stemmy while the grazed patches stay short.

Florida note: Be honest about geography: bird’s-foot trefoil is a cool-temperate forage for zones 3–9, and one garden reference describes it as found throughout North America except the Deep South — and the peninsula is the Deep South. In the warmest parts of the state, do not plant it expecting a pasture; at most, treat it as a cool-season trial where winters actually chill, and expect summer heat to end the experiment. The pollinator value, the nitrogen fixing, and the yellow flowers are real — they just belong to a cooler climate than a peninsula summer.

Saving seeds

Norcen comes from the North Central states breeding effort, and the North Central forage reference rates it plainly: semi-erect to erect habit, high winterhardiness, good yields, maturing midway between Viking (the earliest) and Empire (the latest). A state extension bulletin adds two more selling points: better seedling vigor than Empire, and a high ranking in crude protein. It became the most widely grown trefoil in northern Michigan, which is the kind of adoption that says more than any trial table: farmers replant what survives their winters. As a named, open-pollinated forage variety it comes true from seed: sow in spring or fall at about a quarter inch deep, and inoculate the seed with the right trefoil rhizobium if trefoil has never grown in that soil before. The full method is in the Saving seeds section of the Birds-Foot Trefoil guide.