How to Compost Seaweed

Seaweed is a beneficial compost ingredient.

Seaweed is rich in nutrients like phosphorus, potassium, calcium and nitrogen. Composted seaweed also adds many micronutrients that will improve soil quality and plant health. According to the University of California, bacteria readily feast on seaweed leaves. This makes seaweed work well as an activator for compost piles by speeding up the decomposition process. Fresh seaweed will deteriorate quickly; prepare the material for composting as soon as it is gathered.

Difficulty:

Easy

Instructions

Things You'll Need

• Seaweed
• Water
• Scissors or lopping shears

1. Collect washed-up seaweed from the shore. Look for short-vined seaweeds or grasses like turtle grass, sargassum, manatee grass or shoal grass. Do not collect live seaweeds or grasses from the water as this might cause damage to the ecosystem.

2. Rinse seaweed with clean water to remove salt. Spread the seaweed out in thin layers and water for one hour for each inch of seaweed gathered. This will thoroughly leach salt from the material.

3. Chop seaweed into small pieces using scissors or lopping shears. This will help speed up the decomposition process.

4. Add the seaweed pieces to your compost pile. Mix the pile to achieve even distribution.

Tips & Warnings

• Leave the seaweed out in a heavy rain to help rinse salt away from the plant material.

• Do not add seaweed to compost without rinsing. The salt residue on the plant can kill plant stems and roots that are not salt tolerant.

References

• University of California Cooperative Extension: Composting 101
• University of Florida IFAS Extension: Caring for Plants