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Watering Garden Mums
Garden mums need regular watering because their roots are so shallow. If they are in thin, poor soil they will dry out very quickly any may need supplemental watering every day or two in the heat of summer. If water deprived, they seem to wilt suddenly and dramatically. If they are planted in healthy soil rich in organic matter, they will manage fine if rainfall is normal. Run a dripping hose or sprinkler during droughty periods in high summer. Drought conditions cause mums to become woody and stunted if they are allowed to dry out repeatedly. Keep them well mulched to prevent evaporation of moisture from the soil and absorb maximum water from rains. Mums planted in terra cotta pots are particularly vulnerable to rapid drying out. For information on products see the file on Choosing Watering Equipment
Garden chrysanthemums are heavy feeders because their roots are so near the soil surface. Fertilize in the spring with about a tablespoon of a general-purpose slow-acting granular fertilizer on the soil around each garden mum for the rain to soak in. Then sprinkle another small handful near each plant late in the growing season--about 2 weeks before flowering begins, which in many cases is late August. If you have planted mums in containers with soilless planting medium, be sure and fertilize regularly. For more information see the file for Choosing Fertilizers
For shallow rooted garden mums, mulching is essential. Spread a 2 to 3 inch layer of some organic material such as evergreen boughs, wood chips, shredded bark or chopped leaves from your yard on the soil over the mums’ roots. This mulch helps control weeds, conserves soil moisture, and keeps dirt from splashing up on the flowers during the bloom period. Over time it improves the quality of the soil as it gradually decomposes. In winter, after you have cut back dead stems, add another inch or so of mulch over the dormant plant to buffer the soil against severe temperature fluctuations over the winter which cause it to heave and disturb chrysanthemum roots. For more information see the file on Using Mulch
To encourage compact, bushy plants with lots of flower buds, pinch off the top 1/2 to 1 inches of the growing tips of young seedling stems as soon as the plants are 6 to 8 inches high. This stimulates branching and delays the development of buds until fall. Branches become stronger and plants are bushier. Continue pinching the growing tips and the first set of leaves from each branch until about the middle of July in the North, a bit later in the South. To delay budding until late fall, pinch until August. When buds appear, nip all but 1 or 2 buds from each cluster if you want fewer but larger flowers.
In late fall, after the plants have finished flowering, cut the dried out stems back to within a few inches from the ground. This neatens the planting area and signals the plant to put its energy into root development and tufts of winter foliage to protect it.
Stems of tall exhibition varieties of garden mums may need staking to support their flowering tips. Also, mums that have not been regularly pinched or that have not had enough sunlight will develop long, lanky stems that will need support when they bear flowers. Either tie stems individually to a thin stake in the soil, or set stakes equidistant around a flowering clump and tie string to form a circle to support the stems. For more information see the file Staking Flowers
The easiest way to get more chrysanthemum plants is to divide established garden mum plants. Do this every 2 or 3 years, in early spring when they first begin to send up green shoots. Dig up the entire clump and carefully separate vigorously growing shoots from the outer portions of the clumps, taking care that they have roots attached. Discard older woody central parts of the clump. Plant the new rooted shoots as directed for new plants.
Another way to acquire new mums is to root the pinched stem tips. Strip off their lower leaves, dip them into a commercial rooting hormone powder and insert them into a tray of damp vermiculite or sand. Cover then with plastic wrap or a plastic bag to hold in the moisture and check them in several weeks for signs that they are developing roots. When sufficient roots appear, plant them in pots of soilless mix or into a garden bed.