1. Air (Oxygen and Carbon Dioxide)
2. The Sun or some light or maybe some darkness.
3. Warmth (heat), or maybe some coolness.
4. Water (moisture, dampness)
5. Soil, rocks, compost, sand.
6. Time, lots or maybe little.
7. Creatures, in or above the soil. These could be giant worms or miniscule creatures.
8. Plant food. Fertilisers, minerals.
This list was helped by The Nuffield Space Project P77