Many Dahlia growers grow their plants through a mulch material. This can be a weed membrane or organic material such as straw or compost.

I prefer to use a Barley straw mulch at a rate of 1 bale per 20 plants. This gives a layer of around 6 to 8 inches which over time will compact down to around 4 inches. This can be applied at any point of the growing season, but it is easier to get it around the plants when they are smaller. The disadvantage in my opinion of the fabric options is that it is usually coloured black and as we know from our own clothing this can attract the heat.

The Advantages.

• Prevents weed growth, although you can get a little barley pop up, which is easily removed.
• Prevents the sun getting to the soil and quickly warming it up so making the plant roots hot.
• Keeps the water and any liquid feed available to the plants for longer so reduces watering and feeding.
• Prevents the soil from cooling too quickly after the sun has gone in. This gives a more even temperature all-round, meaning the flower opens consistently over the 25 plus days of development.
• Can be dug into the soil at the end of the year and will help the soil structure.

The disadvantages

• Straw must come from a reliable source and free from any residual herbicides that can later leach out and stunt your plants.
• If you do not maintain your pest controls the straw can act as a hiding place for pests.
• Can get a little dusty and messy when applying it.

The Technique.

• Hoe the ground to open it up and remove any weeds first.
• Water the soil if it has not recently rained
• Apply fertilizer to soil, I use Fast Grow Poultry and Seaweed Pellets for this.
• Apply slug pellets to the ground before putting the straw down
• Loosen the straw from the bale and place around the plants, but do not push it hard against the stems.
• Cover paths as well as beds for best effect.

Although there is some cost and effort involved I feel the benefits far out way this and I wouldn’t grow my Dahlias without it, so if you haven’t done yours it’s never too late to do so.

The photo on the right shows the comparison between using straw as mulch and not.

Dave Gillam