luxuriant growth
芃 centers on lush, vigorous plant growth: vegetation that is thick, flourishing, and abundant.
芃 combines the grass radical 艹 with 凡, which likely contributes a phonetic element. The exact historical development is uncertain, but the character is associated with the idea of abundant plant growth.
The grass radical 艹 sits above 凡, which looks like a spreading base. Picture ordinary grass (凡 as 'common') growing so thickly that it becomes a luxuriant carpet.
For ホウ, imagine a whole field of grass growing so fast it makes a soft 'hoe' sound as it pushes up: hoe -> ホウ, and the field is covered in luxuriant growth.