In Hawaii at sea level, you can plant several types of fruit trees on top of lava with about 2 feet of soil.

In Hawaii at sea level, you can plant several types of fruit trees on top of lava with about 2 feet of soil. These trees can eventually root in the lava as the roots find cracks and crevices to penetrate. Here are some fruit trees that are suitable:

1. Papaya: Papaya trees are fast-growing and can thrive in shallow soil. They will establish roots quickly and can adapt to the rocky substrate.
2. Mango: Mango trees are hardy and can grow well in a variety of soil conditions, including those with lava rock underneath.
3. Banana: Banana plants are not technically trees, but they grow well in shallow soils and can establish roots in lava rock.
4. Guava: Guava trees are tough and adaptable, able to thrive in rocky and shallow soils.
5. Citrus: Citrus trees like lemons, limes, and oranges can be grown in shallow soils and will extend their roots into the lava rock over time.
6. Avocado: Avocado trees can grow well in shallow soils and will send roots into the lava rock, seeking nutrients and stability.
7. Fig: Fig trees are very resilient and can thrive in rocky, shallow soils.

Tips for Planting:

• Soil Preparation: Ensure that the 2 feet of soil is rich in organic matter and well-draining to support the young trees.
• Mulching: Use mulch around the base of the trees to retain moisture and improve soil quality.
• Watering: Regular watering is crucial, especially during the establishment phase, as the lava rock beneath may not retain water well.
• Fertilization: Regular fertilization can help provide the necessary nutrients for the trees to grow in the limited soil.

Over time, the roots of these fruit trees will find their way into the cracks and crevices of the lava rock, securing themselves and accessing additional nutrients and moisture.