Selecting deer-resistant perennials that can thrive in Zone 4b (where winter temperatures can drop as low as -25°F to -20°F or -31.7°C to -28.9°C) and bloom throughout the summer can be a bit challenging, but there are some great options available. Keep in mind that while these plants are considered deer-resistant, hungry deer may still occasionally nibble on them if food is scarce. Here are some beautiful perennials that fit your criteria:

  1. Russian Sage (Perovskia atriplicifolia): Russian Sage is a hardy and drought-tolerant perennial that produces airy spikes of lavender-blue flowers from mid-summer to early fall. Its aromatic foliage is typically left alone by deer.
  2. Catmint (Nepeta spp.): Catmint is a low-maintenance perennial with aromatic gray-green foliage and spikes of lavender-blue flowers that bloom from late spring to late summer. It’s generally resistant to deer browsing.
  3. Yarrow (Achillea spp.): Yarrow is a tough, drought-tolerant perennial that produces flat-topped clusters of colorful flowers in shades of pink, red, yellow, or white. It blooms from late spring through summer and is typically deer-resistant.
  4. Liatris (Liatris spp.): Liatris, also known as Blazing Star, is a striking perennial that bears tall spikes of fluffy purple or white flowers in mid to late summer. Deer tend to avoid it.
  5. Bee Balm (Monarda spp.): Bee Balm is a favorite of pollinators, and its bright, tubular flowers in shades of pink, purple, or red bloom from early to mid-summer. It’s often avoided by deer due to its strong fragrance.
  6. Siberian Iris (Iris sibirica): Siberian Iris produces elegant, delicate blooms in various colors, including blue, purple, white, and yellow, during late spring and early summer. It’s generally unappealing to deer.
  7. Coneflower (Echinacea spp.): Coneflowers are sturdy and long-blooming perennials with striking daisy-like flowers in shades of pink, purple, orange, and white. They bloom from mid-summer to fall and are usually not preferred by deer.
  8. Lavender (Lavandula spp.): Lavender is a fragrant perennial with gray-green foliage and spikes of aromatic flowers in purple, pink, or white. It blooms in mid to late summer and is typically deer-resistant.
  9. Daylilies (Hemerocallis spp.): Daylilies are reliable perennials that offer a wide range of colors and bloom from late spring to mid-summer. They are relatively deer-resistant.
  10. Coreopsis (Coreopsis spp.): Coreopsis, also known as Tickseed, is a cheerful perennial with bright, daisy-like flowers in shades of yellow, pink, or red. It blooms from late spring to late summer and is usually left alone by deer.

Remember that no plant is completely deer-proof, and deer preferences can vary based on local conditions and food availability. To enhance the deer resistance of your garden, consider mixing various types of plants with different textures, scents, and flavors. Additionally, you can employ deer deterrents, such as motion-activated sprinklers or deer repellent sprays, to help protect your plants.