Read "Making a Garden of Perennials" by W. C. Egan online for free on Textopian. Full text with search, annotations, highlights, and AI-powered reading aids.
Do we want a successful flower bed -- one that our neighbors will envy -- or one in which the plants are struggling to exist? If we want the former -- and who does not? -- we must give our plants good pasturage. They are as fond of the fat of the land as we are, and, since they gladden our hearts with their radiant blooms, we should treat them fairly. And how? By giving them a good, deep soil for their root-run, not only rich in food, but loose and friable.
Most all virgin soils contain ample plant food, but the deeper part lacks the result of the action of air, sun and frost, and the natural humus of decayed leaves and grasses. The plant food it contains is "uncooked" -- that is, not ready for plant assimilation. Therefore, the beds to contain your perennials should be dug at least two feet deep -- three is better -- and good garden soil, or soil from a corn-field or any hoed crop where the weeds have been kept down, used to supplement all but the top layer one foot in depth. All of this applies to tree and shrub holes also. This top layer of one foot in depth is apt to be in fair condition for immediate use and may be applied in the bottom of the bed, mixed with either fresh or rotted manure. The soil brought in may be mixed with old manure and placed on top.