A proposal for Duet restaurant
Winter decoration for Duet's planters
Please consider following winter decoration proposal for Duet's rectangular planters.
Since you mentioned you want to spend as little as possible on it the options will be presented in "cost low-to-high" order.
The least expansive option is to remove faded mums, leave ornamental kale in place and replace mums with winter garlands similar to following:


Lighted garlands cost more.
Garland can be decorated with removable Christmas decor such as balls, artificial poinsettia flowers, bows etc.
Garlands can be real or artificial and cost $50-$100 each.
Second, more expansive option is to replace mums and kale with winter installation similar to following. The cost varies depending on supplies used:

And last, most expansive option is to create a winter installations using large outdoor lighted balls, which would resemble your interior design, similar to following:


The cost of outdoor lighted balls starts from $75 each + a cost of winter installation, which varies depending on supplies used.
Please let me know which option you choose.
Thank you!