The spreading hedgeparsley plant aligns well with the energy flow of the Northwest direction. Its unassuming yet pervasive growth patterns may theoretically correspond to the metal element in Feng Shui, symbolizing steadfastness and resilience. This makes it an intriguing fit for spaces requiring a subtle dose of such energies. Yet, the nuanced interplay of Feng Shui elements could resonate differently with everyone, hence further exploration is advised.

The ngaio exhibits intriguing harmony with a West-facing direction. This tree vitalizes the metal element, associated with West in traditional Feng Shui, by passively encouraging the flow of Chi. However, interpretation varies, and the user's personal affinity should be considered.

The zebra plant is moderately well-suited for East-facing spaces. Its vibrant green leaves and striped pattern symbolize growth and movement, which can harmonize with the wood element dominant in the East. However, the zebra plant's preference for indirect light may conflict with this direction's naturally bright energy.

The hairy alumroot could help harmonize energy in a Southwest-facing zone due to its robust features and grounding energy, as per Feng Shui theories. It's important, though, for each individual to feel a positive connection with the plant which is unique and personal.

Garlic and Feng Shui have a complicated rapport. As the plant has strong protective energies, its placement holds significance. Particularly suited for Southwest-facing locations, it can balance the Yin and Yang energies, as this direction is governed by the earth element which resonates well with garlic's grounding vibes. Yet, it should be noted that Feng Shui is a sublime art with multifaceted interpretations, so personal intuition plays a crucial part.

White deadnettle may bring a harmonious flow of energy when placed in a West-facing direction. The plant's white blooms are thought to represent purity and clarity, aiding in dissipating negativity and promoting a sense of tranquility. This suggestion, however, should be considered in conjunction with other factors, as individual Feng Shui interpretations may vary.

The beach spider lily exudes an aura of peaceful vitality, quite suitable to the North-facing energy flow that symbolizes growth and the flow of life in Feng Shui. Its white flowers match the color element of the Northern quadrant as well, enhancing its harmonious integration in this setting. However, Feng Shui's personal nature should not be forgotten, often demanding individual adjustments.

The melampodium exhibits a well-balanced energy, conducive to harmony and prosperity when placed in the Southwest-facing direction. Its compact growth aligns with the element of Earth, symbolizing stability and thoughtfulness, commonly associated with the Southwest direction in Feng Shui.