Hardy, garden chrysanthemums can be purchased from garden centers and other outlets in the spring and fall. Although fall is the time we enjoy the beauty of their colorful floral displays, spring is the best time to plant garden chrysanthemums. Spring-planted garden mums have the best chance of successfully overwintering in cold climates.
Garden chrysanthemums can be planted from spring through mid- to late July. Plant them in a well drained location that receives full sun. Plant them at the same depth they were growing in the container. Space chrysanthemums 18 to 24 inches apart in the garden, depending on the mature size of the variety. Water them thoroughly at planting and once a week through the summer during dry weather. Fertilize newly planted mums with a complete analysis, water soluble plant food and continue fertilizing once a month through mid-July to encourage vigorous growth.
Chrysanthemums grown for spring sales may have been forced into bloom. After the flowers fade, prune the plants back to about one-third to one-half of their flowering height. This will produce a sturdy, compact plant that will bloom again in the fall.
Cuttings of chrysanthemums can be taken in early spring to early summer from plants already established in the garden. This in an inexpensive way to increase the number of plants in your garden or to share with gardening friends. Take cuttings when the new shoots are 3 to 5 inches tall. Use a sharp knife to take a 2- to 3-inch cutting from the end of the shoot. Remove the leaves on the bottom half of the cuttings. Insert the cuttings in a flat or pot containing moist perlite. Insert the cutting into the perlite up to its first leaves. A rooting hormone can be used to speed up root formation, however, roots will form without it.
Keep the perlite moist at all times. Chrysanthemum cuttings will root in 3 to 4 weeks. When the roots are 1 to 1 1/2 inches long, remove the cuttings and plant them into small pots containing fresh potting soil or plant them directly into the garden. Pinch off the top 1/2 inch of the small plant to encourage branching. Continue to pinch all shoots every 2 to 3 weeks until late June. This will produce full, mound-shaped plant.
Chrysanthemums sometimes become crowded in the garden. The old, center portion of the plant dies back and the new growth occurs around the perimeter of the clump. Renovating chrysanthemum clumps every 3 or 4 years will encourage healthy growth, neat plant growth habit, and continued flowering. When new shoots appear in the spring, dig the entire clump. Use a sharp spade or knife to cut the clump into wedge-shaped sections, like a pie. Remove and discard the point of the wedge (this is the oldest part of the clump). Plant the new plants, "wedges", 18 to 24 inches apart at the depth they were growing. Water and fertilize as described above.
This article originally appeared in the March 14, 1997 issue, p. 21.