Planting Hardy Mums and Asters

Posted at 9:19am on August 29, 2017

Chrysanthemum and Asters are traditional fall staples, and for good reason. They provide lasting color later in the season, when most plants are finished with their lustrous displays. When pruned properly, Dome Asters and hardy mums give the appearance of mini shrubs. This makes them perfect for colorful borders or to add structure to a small area. Their compact habit and beautiful blossoms make them popular; however, there are a few tips and tricks to these fall beauties

Hardy mums and Asters are tolerant of our temperatures once established. However, they typically require care in planting in order to thrive season after season. Provide adequate drainage by incorporating compost or garden soil when planting. Both of these plants prefer rich, moist, well drained soil. The major issue most have in our region is clay. If heavy clay is present, mix the back fill material 50/50 with high quality compost. When the soil is sandy or loamy mix 2 parts native soil to 1 part compost/peat moss. Loose soil texture and proper drainage encourage new root growth.

Mums and Asters can be prone to crown rot. Therefore, place the crown of the plant well above the soil surface to prevent this. To do this back fill the hole with soil until the soil-surface of the potted mum is slightly above the existing soil line. Mulch well to protect the root system from drying. Make sure to keep mulch pulled slightly away from the basal stem. Water every day to every other day for the fist few weeks, and slowly taper off as the season progresses. Water from the side of the plant to avoid water pressure splitting open the dome shape of the plant.

Another important tip for successful overwintering of chrysanthemums is to plant as early in the season as possible. This will allow adequate time for the plant to root. Root stimulator or starter fertilizers are very helpful in boosting root development. A healthy root system leads to a healthy plant. Fertilize through the season to promote budding and healthy growth.

Pruning mums is essential for fall color and to maintain a rounded structure. The general rule of thumb is to prune at least four times before the 4th of July. Each prune should take off no more than 1/3 the total plant, becoming less severe each time. This encourages branching, rounded structure, and prolific fall blooming. After the plant has finished blooming lightly trim off spent blossoms. Then mulch well to protect for the winter. Do not cut down the plant until spring (around April).

Written for The Green Thumbers by Elaine Guthrie