Even though spring is the best time to plant perennials (including perennial mums), trees & shrubs, you can plant them right now if you follow these tips.
1. Plant prior to September 1 – plants need at least 6 weeks to get roots as far into the ground as possible prior to killing frost, which is typically by mid October.
2. Keep well watered – nothing stresses plants more than to be drought stressed prior to the ground freezing. We believe that had as much to do with plants not surviving the past 2 winters as the cold winter weather. If plants are too dry their roots aren’t healthy & strong enough to combat further stress from the weather (or bugs & diseases either). The best time to fertilize is when the plant is actively growing, so as we get closer to frost, just plain water is efficient.
3. Mulch after the ground freezes – only after the ground freezes & plants have gone dormant (no longer growing and look like they’ve died) for the winter, put hardwood mulch over the plants at least 3-4″ deep & 2-3 feet wide to insulate roots & base of plant from winter cold. Do not use leaves to mulch plants, as they can smother and kill plants during the winter. Make sure to remove mulch as soon as bulbs like daffodils & tulips begin blooming in the spring so that they aren’t smothered or get too hot.
Of course the most obvious tip that should have been listed first is to choose varieties that are hardy to at least zone 4 (or zone 3 for upper Minnesota), which have the best chance of surviving our winters. We list the hardiness zone on our signs, as well as on our website, and will replace our perennials that don’t survive the winter.