This is a good example of how plentifull seaweed can be when blown onto the beach by storms. This is at Lahinch on the west coast of Ireland.

Seaweed is largely under-appreciated in the gardening world, classed merely as a soil conditioner or a fertiliser. Its benefits are so extensive, though, that it really should be given top billing as part of any maintenance programme for the growing of plants.

Seaweed contains over sixty minerals and trace elements, along with numerous bio stimulants, and it also contains iodene which is an excellent disease suppressant. As you can probably tell, I’m a bit of a fan of our sea-borne, slippery friend, and no wonder. All of the above reason contribute to make seaweed a top class supplement for both grass and garden.

The Wonder of Seaweed in Your Garden

Seaweed can be used as a fertiliser or soil conditioner in many different forms, for example:

  • Seaweed can be dug into your soil in it’s raw form, straight from the beach
  • Seaweed can be dried and either granulated or powdered
  • the goodness can be extracted from seaweed to form a concentrated seaweed liquid.

In modern fertilizer use, liquid seaweed makes a highly efficient base for the nutrition of a wide variety of plants. This is because it can be safely mixed with most of the commonly used sources of nitrogen, phosphate and pottassium, along with supplements like iron. The seaweed stimulates the soil bacteria which, in turn, helps to release much of the nutrient content. In many cases these nutrients are fixed in the soil and not available to plants, whether you’re feeding grass, tomatoes, vegetables or flowers. Seaweed combats this, helping you to make the most of any nutrients being applied, and reducing the quantity required for healthy growth.

To add to the list of benefits, seaweed is also valuable in helping to break down organic matter. This is a particular benefit when treating turf, where thatch can be a serious problem if not managed properly. Finally, as if we haven’t heard enough about the wonders of seaweed, it’s also very high quality food supplement for both animals and humans. But, let’s not get greedy – before we go and eat up our entire supply, let’s first deal with its uses and benefits on our lawn and garden.

Seaweed Fertiliser: Discovering the Benefits

Harvesting seaweed on a typical sunny day in the north of Scotland

The benefits of using seaweed on plants was first discovered many years ago by farmers living and working beside the sea. They would harvest the seaweed from the shore as it was washed in by storms, then spread it on the land prior to planting the crops. The benefits were particularly noticeable on potatoes, always susceptible to disease, as the fields treated with the seaweed consistantly produced better crops with very clean skins.

One side effect to seaweed use was the presence of a very distinctive flavour in the potatoes, something quite noticeable when compared to normal potatoes. This is something that is no longer an issue, though, now that farmers have access to very easy-to-apply granular fertilisers. This variation of the seaweed fertiliser doesn’t have the same side effect, the strange taste disappearing during drying or granulation.

The seaweed fertiliser was also found to improve soil quality over a number of years. This is now known to be because the alginates act as a floculator, breaking down heavy soils into a crumbly free draining material. Conversely, almost fifty percent of the seaweeds constituents are humous forming, so light sandy soils become more fertile and less prone to drought damage.

How Can Seaweed Help Your Garden?

Seaweed Fertiliser's effect on a patch of grass - green lawn grass with one application

This is the same area of turf in mid June after one application of seaweed meal and sulphate of amonia

Before the use of seaweed fertiliser on a lawn

This is an area of badly worn turf at the end of March before any Spring fertiliser is applied.:

As you will see from the pictures above, seaweed can work wonders for your garden in many different ways. The following are examples of how seaweed can be used to help you in your garden:

  • Flowers tend to produce more vibrant colours with application of seaweed
  • Vegetables produce healthier disease free crops
  • Seaweed treated Grass will be greener and produce a healthy dense sward, providing other maintenance  work is carried out correctly
  • Seaweed helps to prevent club root and blossom end rot
  • Seaweed will prevent blight and scab on potatoes
  • Dusting plants with seaweed powder deters blackfly and greenfly
  • Carrots applied with the seaweed dust seldom suffer damage from carrotfly

Applying Seaweed Fertiliser to your Garden

This is a great example of the vibrant colours that are achievable in the garden.

If you are lucky enough to have access to fresh seaweed it can be spread straight onto the garden. Although it can be dug into the drills fresh with potatoes, the best way is to collect it during Autumn and Winter when stormy seas will provide you with ample material. Then you can spread it onto the surface of the vegetable garden where it will break down a little over the cold season, suppressing weeds as an added bonus. Then, when spring comes around, you can dig the material straight into the soil.

Seaweed can also be used as a mulch in and around shrub beds, annual and perennial borders, where it will break down slowly, releasing nutrients into the soil, while again acting as a natural weed suppressant. The one exception would be to avoid treating rhododendrons, azealias and other acid loving ericacious plants. This is because seaweed creates quite alkaline conditions, not conducive to these types of plants.

Looking for Pre-Prepared Seaweed Fertiliser?

If you don’t have easy access to the beach, then there are a range of pre-prepared seaweed fertilisers on the market. You’ll find seaweed extract as one option, and this organic concentrated seaweed fertiliser from Shropshire Seaweed is a good option.

I hope you enjoyed my guide to seaweed, it’s benefits and where you can use it in your garden. Next week I’ll be posting an article on the different types of seaweed products that are currently available to the home gardening and lawn care market. I hope you come back to find out more.

Update: You can now find this article here: What Seaweed Fertiliser is Right For Your Garden

If you have any experience of using seaweed yourself, I’d love to hear about it. Please leave me a comment in the comments area below, letting me know what you think about seaweed for lawn and garden care. Your experience would be much appreciated.