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.
Many combinations may be used whereby a certain area may be made to produce a double crop of bloom, and thus prolong the flowering season within that area. Peonies, which are planted two and a half to three feet apart, may have the "Lilium superbum", the later varieties of gladiolus, or "Hyacinth candicans" planted in between them; the last two should be taken up each fall as they are not hardy in all sections. The lilies will require resetting every few years, as they travel around in their new growth, and may invade the peony roots. These will flower above the peony foliage. Fall is the best time to plant any lily.
The shooting star ("Dodecatheon media") may be planted between the spreading dwarf plants of that admirable bell flower ("Campanula Carpatica"). The bell flowers may be planted eighteen inches apart and, in the spring, when the shooting stars are up and in bloom, the foliage of the campanula is hardly in evidence, but during the summer it occupies all the space between them.