Numerology energy is revealed by calculation of names and dates. Calculating the name of a direction can reveal the energy represented by that word, but the direction itself is not calculated.

In other words, the direction itself is outside the realm of numerology, but the name for the direction can be calculated.

The any text calculator can be used to calculate words or groups of words. Using that calculator, it is seen that "South" calculates to the number 2. The energy represented by the number 2 relates to coexistence and relationships.

Regarding why sunflowers look to the south, perhaps a biologist, an agriculturist, or other specialist of plants or plant behaviors can provide an answer for you.