millet
秠 centers on millet, a type of grain. The meaning is specific and narrow, referring to the plant or its seeds.
秠 combines 禾 (grain) with 丕, which likely contributes the sound. The character is a phono-semantic compound for a type of grain, specifically millet.
The grain radical 禾 on the left, combined with 丕 on the right, can be remembered as a specific grain: millet. Picture a field of millet with a distinctive tall stalk that looks like the shape of 丕.
For ヒ, imagine a small heap of millet grains: heap -> ヒ. The heap of millet helps you recall the reading.