Would a creeping phlox survive year after year if I put them in a container like the one in the link below and hang them somehow on my fence. Would their roots go deeper in the soil? how deep? Thank you very much.
Thank you for your question. Although creeping phlox, a herbaceous perennial, is best suited as a ground cover, you can certainly grow it in a container. Bloom time is spring and early summer. Using a container with good drainage holes, is a great way to slow its vigorous spread. If hung on a fence, your container will require more moisture than sitting it on the ground due to evaporation and wind exposure. This fast-growing plant with shallow roots will soon fill a container. Depending on the size of your pot, place each plant 6 inches apart for efficient growth. Be careful not to overcrowd your container. Use an all purpose potting soil and add some water soluble fertilizer or organics to encourage blooming. For best results, however, plant it in a sunny location where soil can be kept slightly moist and well drained. Water regularly but allow the soil to dry slightly between each watering to prevent rot. Your plants may require a slightly shaded location to survive in the intense heat of the summer.
You can find more information provided in the link to the article from Gardening Know How
Winter conditions are harsher to perennials in containers than those in the ground. Wind and cold air temperatures can cause the soil to heave and damage the root system. This would leave your plants vulnerable to survival. Your plant can be overwintered in an unheated garage or shed. Another option would be to dig or sink your container into the soil so that it is sitting at the same level as the ground in order to avoid excessive freezing and thawing. A further option is to group your container with other containers away from wind and excessive sun and surround with leaf mulch, straw or bark mulch. Water containers until soil freezes.
The link to the following article from the University of New Hampshire provides further information about overwintering perennials in containers.