English Walnut + Clover

English walnut produces juglone at much lower concentrations than black walnut, which makes it compatible with a wider range of understory plants, including clover. White clover or crimson clover seeded into the rootzone acts as a living mulch: it fixes atmospheric nitrogen, suppresses annual weeds, and keeps pollinators active during the walnut's bloom window, which can improve nut set in plantings with marginal pollinator pressure.

Spacing matters less here than with black walnut. Clover can be sown directly under the canopy once trees are established (typically year three or later), when the canopy provides partial shade that white clover tolerates reasonably well. On heavy clay soils, clover's root activity improves drainage and organic matter over time. The pairing is less useful in very dry summers: clover thins out under drought stress and may require overseeding. Mow before clover sets seed if reseeding pressure is a concern.