Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

When should I pinch my mums?

Garden chrysanthemums, the flower which most typifies fall, need some attention at this point to guarantee timely autumn bloom. The spring growth of the chrysanthemums should have been pinched or sheared back with a sharp grass shears by half when it approached 6-8 inches. The secondary growth resulting from this pinch should have also been pinched back when it approximated this same length. This process could have already been done 2-3 times during late spring and early summer and by now the plants are again ready for another and final pinch. This practice is usually halted by July 15, though you can pinch as late as July 22 without harming fall bloom. If pinching occurs much later than this date, blooming may be delayed and resulting flowers subjected to early frost.

If you haven't been able to judiciously follow this pinching schedule, your plants may now be tall and setting early flower buds. Stem growth may also be weak and toppling over. In this situation, cut the plants back to 12 inches high with a sharp pruners. All of the nodes will quickly break out with new growth and you will still be amply rewarded with compact plants filled with bloom in fall.

Mums are photoperiodic with flower buds being initiated when periods of darkness extend beyond 12 hours each day. This occurs naturally outdoors when the days of summer become shorter. As we gradually progress into autumn, chrysanthemums can be divided into response groups with some cultivars coming into full bloom 6 weeks after the beginning of short days and others being much slower with bloom taking up to 8 or even 10 weeks. This is why some mum cultivars will be in full bloom at the end of September while others will still be in tight bud waiting until mid-October to flower. The very late response types such as the 9 or 10 week groups will not flower until the beginning of November and therefore are not suitable for outdoor culture because their blooms will be lost to early frosts. Many of the greenhouse mums fall into this category.

Feeding with a low nitrogen fertilizer such as 6-12-12 or 5-10-10 at recommended rates for the remainder of the summer will continue healthy growth, and still keep plants compact with a good bud set. A light application after the final pinch when new growth has started, and a final feeding in mid-August will be sufficient. Always thoroughly work any granular fertilizer into the soil and water sufficiently afterward. An appropriate water soluble fertilizer is easier to apply and will provide good results. Follow label recommendations when applying fertilizers. Avoid feeding after mid-August when plants are setting bud and there is no need to promote growth.