Looking for a mulch that does more than simply cover the soil? Lucerne mulch is widely regarded as one of the best organic mulches for vegetable gardens because it helps conserve moisture, suppress weeds and improve soil health as it breaks down.

Particularly useful during hot Australian summers and periods of water restriction, lucerne mulch helps keep soil cooler, reduces evaporation and adds valuable organic matter to the garden. It is especially popular around tomatoes, basil, capsicums, fruit trees and other productive crops where healthy soil and consistent moisture are important.

To start with, Lucerne and Alfalfa are the same plant, Medicago sativa. In North America it is commonly called Alfalfa, while in Australia, Europe and the United Kingdom it is generally known as Lucerne.

How to Use Lucerne Mulch

Quick Facts

Excellent mulch for vegetable gardens
Helps conserve soil moisture
Suppresses weeds naturally
Adds nitrogen and organic matter
Improves soil structure
Encourages earthworms and beneficial microbes
Moderates soil temperature
Suitable for vegetables, fruit trees and ornamental plants
Breaks down in around 4–6 months

What is Lucerne Mulch ?

Lucerne mulch is made from the stems and stalks of Medicago sativa, the same plant commonly grown for stock feed and hay.

In the garden, these stems are used as mulch where they gradually break down and improve the soil.

Because lucerne belongs to the legume family, it is valued for the nutrients it contributes as it decomposes, particularly nitrogen.

Many gardeners consider lucerne mulch one of the premium organic mulches because it combines moisture retention, weed suppression and soil improvement in a single product.

Why Use Lucerne Mulch?

Conserves Water

Lucerne mulch forms a protective layer over the soil surface, reducing evaporation and helping the soil stay moist for longer.

This can reduce watering requirements during hot weather and drought conditions.

Helps Suppress Weeds

A good layer of mulch blocks sunlight from reaching weed seeds, helping to reduce germination and making garden maintenance easier.

Improves Soil Health

As lucerne breaks down it adds organic matter to the soil, helping improve structure, aeration and moisture retention.

Adds Nitrogen

One of the major reasons gardeners choose lucerne mulch is its ability to contribute nitrogen and other nutrients as it decomposes.

Encourages Earthworms

Earthworms thrive beneath lucerne mulch where moisture levels remain stable and organic matter is readily available.

Nutrients Found in Lucerne Mulch

Lucerne belongs to the pea family and is valued for its nutrient content.

As it breaks down it contributes:

Nitrogen
Potassium
Calcium
Iron
Trace minerals
Organic matter

These nutrients help support healthy plant growth and improve long-term soil fertility.

How to apply Lucerne Mulch

You can buy Lucerne in bales or ‘chopped’ in compressed bales. The chopped variety is easier to spread than the bales, however both work in the same way.

Weed before spreading the mulch
Make sure the soil is moist before spreading.
Apply at around 3-4 cm deep in vegetable gardens.
Around ornamentals, apply at 10cm.
Water after spreading.
Keep the mulch away from the stems of plants.
Use a liquid fertiliser as required.
Mulch can be raked back to apply pelletised fertiliser.

Best Uses for Lucerne Mulch

Vegetable Gardens

Lucerne mulch is particularly effective around:

Tomatoes
Capsicums
Eggplants
Basil
Cucumbers
Zucchini
Beans

It helps maintain even soil moisture and supports healthy plant growth.

Fruit Trees

Lucerne mulch works well around citrus, apples, pears and stone fruit trees by reducing weed competition and conserving moisture.

Raised Garden Beds

Because it breaks down into valuable organic matter, lucerne is ideal for raised vegetable gardens where soil improvement is a priority.

Flower Gardens

Roses, perennials and annual flowering plants all benefit from improved moisture retention and healthier soil.

How Long Does Lucerne Mulch Last?

Lucerne mulch generally lasts around 4–6 months depending on:

Climate
Rainfall
Application depth
Soil conditions

As it breaks down it can be turned into the soil where it contributes valuable humus and improves soil structure.

Many gardeners simply top up the mulch layer once or twice each year.

Lucerne Mulch vs Pea Straw

This is one of the most common questions gardeners ask.

Both are excellent organic mulches.

Lucerne Mulch

Higher nutrient content
Generally contains fewer volunteer seedlings
Slightly slower decomposition
Often considered the premium option

Pea Straw Mulch

Usually less expensive
Breaks down a little faster
Excellent for vegetable gardens
May occasionally produce pea seedlings

Overall, many gardeners consider lucerne mulch the best all-round organic mulch, although pea straw remains an excellent alternative.

Lucerne Mulch vs Sugar Cane Mulch

Compared with sugar cane mulch:

Lucerne Mulch

Adds more nutrients
Contributes more nitrogen
Breaks down more quickly
Improves soil fertility rapidly

Sugar Cane Mulch

Often lasts slightly longer
Usually has a tidier appearance
Excellent weed suppression

Both are excellent products, however vegetable gardeners often favour lucerne because of its nutrient contribution.

Common Questions

Is Lucerne Mulch Good for Vegetable Gardens?

Yes. Lucerne mulch is widely regarded as one of the best mulches for vegetable gardens because it improves soil health while helping conserve moisture and suppress weeds.

Does Lucerne Mulch Add Nitrogen?

Yes. As a legume-based mulch, lucerne contributes nitrogen as it decomposes.

Is Lucerne Better Than Pea Straw?

Both are excellent. Lucerne generally contains more nutrients and breaks down slightly more slowly.

How Often Should Lucerne Mulch Be Replaced?

Usually every 4–6 months depending on climate and application depth.

Is Lucerne Mulch Worth the Extra Cost?

For many gardeners the answer is yes. The additional nutrients, soil improvement and moisture retention often justify the higher purchase price.

Are There Any Disadvantages?

The main drawback is cost.

Lucerne mulch is usually more expensive than sugar cane mulch or pea straw.

It is also worth considering where the product is sourced. Locally produced mulch generally has a lower environmental impact than material transported long distances.

Benefits of Lucerne Mulch at a Glance

Conserves moisture
Reduces watering requirements
Suppresses weeds
Improves soil structure
Adds nitrogen and nutrients
Encourages earthworms
Supports beneficial soil microbes
Moderates soil temperature
Suitable for vegetables, fruit trees and ornamentals
Fully biodegradable