Only a physical barrier like sturdy fencing will reduce the risk of deer browsing enough to be reliable. (That said, even fenced-in public gardens occasionally need to chase deer out that find a way in. Fences will need routine maintenance to keep them functional.) Deer repellent sprays sometimes work, but come with the caveats of needing regular re-application (every time there is enough new growth that is unprotected, plus after every moderate/heavy rain) and sometimes needing to be alternated between brands with different ingredients if the deer get used to a certain blend.

Deer can nibble on any plant as they explore, learn what to eat, or eat materials in starvation desperation. Their diet can vary from summer to winter as well. Usually, they avoid plants that are very pungent (leaves have a strong scent when crushed), prickly/thorny, vert fuzzy, or poisonous to herbivores. That said, they can even eat toxic plants (in moderation), so nothing is truly 100% safe.

Based on the plants in the pictured plan, we have some feedback:

• 'Summer Snowflake' Viburnum is a variety of Doublefile Viburnum (botanical name Viburnum plicatum tomentosum). We don't recommend Viburnum plicatum for Maryland gardens (despite being commonly planted) as it can behave invasively, with seedlings spreading into natural areas and out-competing native plants. Although not as rampant as other invasive shrubs thus far, we suggest asking for a substitute option from the landscape designer.
  
• No variety/species of Hydrangea is reliably deer-resistant; all are fairly palatable, unfortunately. As a fairly new variety, 'Eclipse' has a pretty unique look with its plum-purple foliage, but be aware that it might be eaten. Even if deer don't remove too much foliage, their nibbling might take off flower buds, meaning that the shrub will not flower well, if at all. The "blue" hydrangea and hydrangea tree noted on the landscape specs are in the same boat in terms of browsing vulnerability.
  
• Boxwoods are pretty reliable in terms of deer avoidance, but some varieties have better pest and disease resistance than others. While no boxwood (or any shrub, for that matter) is immune to potential problems, boxwoods as a group can be quite vulnerable to a few pests and diseases: namely Boxwood Blight, Volutella Blight, and Boxwood Leafminer. If you can find cultivars that suit your needs for mature size (avoid relying on regular or heavy pruning to keep them a certain size or shape), choose those with noted resistance to at least Boxwood Blight, if not two or all three of those conditions. We don't have a reference list of which cultivars those are, but at least a half-dozen or so are on the market nowadays.
  
• 'Lavender Twist' Redbud is a weeping, somewhat contorted-branch variety of Redbud tree, and while it is compact compared to the wild type, it still should be given enough "breathing room" if sited near a wall. Make sure the trunk is placed at least 6 or so feet from a wall (10 feet may be better) unless it's going to have special treatment, like being grown as an espalier (not a widely-used technique, which also requires routine maintenance to maintain that special form). Given the growth habit of that variety, we don't think espalier is what the designer had in mind for its use, in which case its position near a wall may be concerning depending on how much room it has.
  
• The roses that appear to be included on the design plan are definitely at risk of being eaten by deer; deer love roses, at least the flowers (the most important part). There is no deer-resistant rose variety, so if you really want to include roses, they may need to be protected with fencing or netting. (Deer netting is more risky to use in terms of accidentally entangling wildlife like birds, squirrels, and snakes, so fencing is better.)

While there are more options for deer-resistant perennials and shrubs among non-native species than native species, there are other plants you can consider depending on site conditions like summer sun exposure, soil drainage, desired mature size and so forth. Make sure the designer doesn't include invasive species, several of which have been prohibited for sale (to take effect in the next couple or so years) by the Maryland Department of Agriculture, such as Japanese Barberry (Berberis thunbergii), Butterfly Bush (Buddleja davidii), Heavenly Bamboo (Nandina domestica), and Burning Bush (Euonymus alatus). Even though such species are usually left alone by deer, their spread into natural areas further damages the ecosystem and displaces native plants that wildlife (pollinators, birds, etc.) relies on.

We don't have a thorough list of deer-resistant plant options, but possibilities among native plants include varieties of Inkberry Holly (Ilex glabra), dwarf cultivars of American Holly (Ilex opaca), Adam's Needle Yucca (Yucca filamentosa), Steeplebush and Meadowsweet (Spiraea tomentosa and Spiraea latifolia/alba, respectively), Bushy or Shrubby St. Johnswort (Hypericum densiflorum or prolificum, respectively), False Indigo (Baptisia species), Milkweeds (Asclepias species), various ferns and grasses, Mountain-mint (Pycnanthemum species), Virginia Bluebells (Mertensia virginica), and Scarlet Bergamot/Beebalm (Monarda didyma).

Miri

Wow, Miri … this is great. 

You're welcome!