The string of hearts embodies vibrance and resilience, qualities often viewed favorably in Feng Shui. It is especially compatible with the Southeast direction, a region associated with wealth and abundance. Having this plant in your house promises to cultivate an atmosphere of growth, vitality, and continuous improvement, in the perspective of Feng Shui. However, interpretation may vary as Feng Shui remains largely subjective.

In Feng Shui, peach-leaved bellflower is often perceived as harmonious, promoting a serene atmosphere with its gentle hues. Facing South, it may help to appease the fiery energy of this direction, providing a gentle balance. Yet, due to the subjective interpretation of Feng Shui principles, compatibility could differ greatly among different individuals and settings.

The rattlesnake plant has a unique, intriguing aura. It is closely associated with preserving tranquility and expanding imaginative thinking. It is commonly believed to be compatible with an East-facing direction. This is because East signifies growth and revitalization, similar to the lively presence of the rattlesnake plant that symbolizes constant evolution and renewal.

Lady's thumb harmonizes with the South-oriented setup. Its vibrant green leaves, symbolizing life-force energy, fuel the 'Fire' element predominant in the South. However, personal experiences may vary. As Feng Shui is highly individual, there is no one-size-fits-all solution.

The common bird's-foot trefoil is generally thought to convey a balance of Yin and Yang energies. It might be especially harmonious when oriented to the North, a direction linked to water's fluidity, in concert with the common bird's-foot trefoil's adaptive nature. As in Feng Shui interpretations, this compatibility might vary on a case-by-case basis.

The scarlet sage harmonizes well with a south-facing setting, one of the resonances being its vibrant red hues that align with the Fire element, typically associated with the South in Feng Shui. This connection may boost positive energy flow or 'chi'. However, Feng Shui interpretations vary significantly, hence the effect might differ.

Traditionally, the sweet pea is seen as a harmonious entity in Feng Shui. Its positive attributes including inducing calmness, enhancing emotional well-being, and promoting restoration align well with the South-facing direction, converging the energies with the notion of ‘Li’, representing fame and reputation in the Feng Shui BaGua. Nonetheless, personal experiences with Feng Shui may vary, and the guidance here serves only as a broad reference.

The calla lily is suggested to have a gentle congruity with the North-facing direction. The reasons are largely related to the symbolism of water inherent to that direction in Feng Shui. The calla lily, with its soothing colors and water-like spots, can act as a subtle enhancer of such properties, further softening and harmonizing the energy flow.