Organic Gardens Network™: How to Use Seaweed to Mulch Your Garden

By Greg Seaman, Eartheasy.com

Seaweed is among the best gifts nature makes available for the gardener.

Seaweed will benefit your garden any time of year, but it is especially useful as a mulch to protect plants during hot, dry weather. In our garden, we’ve come to rely on seaweed as a valuable, yet free, source of fertilizer, mulch and organic pest control all in one natural material.

Benefits of seaweed for gardening

Gathering seaweed for the garden has always been a favorite outing for our family. We usually take a small skiff to a nearby beach and load up with as many sacks as we can safely transport home. It’s fun for children, as they can participate as well as an adult, or they can simply enjoy the beach while we gather the seaweed. As we fill up our sacks, our thoughts drift to the many benefits this will bring our garden.

Saves water, keeps soil moist at ground level The purpose of any mulch is to keep garden soil from drying out at the surface. And by preventing moisture from evaporating, mulch reduces the need for watering. The practice of mulching is essential in areas where conditions are hot and dry.
Eliminates the need to weed Mulch covers the soil and blocks new weeds from sprouting. Because the soil beneath the mulch remains moist, any weeds which do manage to sprout through the mulch are easy to pick.
Repels slugs and other pests Slugs are immediately repelled by two things – salt and sharp-edged materials. Seaweed has a natural salt content which repels slugs, and within a few days of application it dries and becomes quite crispy. Slugs do not like “crispy” surfaces, as the sharp salty edges cut into the soft body tissue. While some mulches may provide hiding spots for slugs, earwigs and other pests, seaweed mulch does not have this disadvantage.
Enriches the soil Seaweed is a broad spectrum fertilizer that is rich in beneficial trace minerals and hormones that stimulate plant growth. Seaweed is high in carbohydrates which are essential building blocks in growing plants, and low in cellulose so it breaks down readily. Seaweed shares no diseases with land plants.
Boosts lethargic plants Seaweed fertilizer contains an abundance of fully chelated (ready to use) micro-nutrients which can be readily absorbed by plants without any further chemical decomposition needed.
Helps lighten the soil Compacted soil can benefit as seaweed mulch breaks down. As the material becomes incorporated into the soil, aeration is improved and the soil becomes more crumbly and moist.
Does not contain weed seeds, unlike bark mulch Two years ago we used commercial bark mulch to cover our garden pathways for the purpose of blocking weeds. Today, these pathways are sprouting horsetail, an invasive weed which can be difficult to eradicate. Seaweed does not bring any foreign weed seeds into your garden.
It’s free!