Now that spring has arrived, the weather is finally getting sunnier, but gardeners should be aware that the warm temperatures can encourage diseases such as black spot, which can greatly damage roses. Black spot is a serious fungal disease named after the big dark splotches that can appear on rose leaves once the plant is infected. It can only thrive in warm, rainy conditions, so it tends to be very common in the springtime.

Black spot disease will not outright kill rose bushes but will greatly drain their energy. As a result, they will not bloom properly and will only produce small shrivelled flowers that can make your garden look less attractive. The disease also greatly weakens roses, so they cannot fight off common stresses such as pests or drought once summer arrives and can die if left untreated for a long time. 

Louise Findlay-Wilson, a gardener and founder of Blooming Lucky, has warned that black spot disease begins spreading in spring but can be easily prevented by performing a few simple tasks. 

How to prevent black spot disease on roses 

Clean up leaves around your garden

The best way to fight black spot disease is to simply keep your garden tidy. It commonly spreads on wet, decaying foliage leftover from winter. 

Louise said: “The disease is easily spread on the wind, and the fungus spends the winter on fallen leaves. The spores are then in a prime position to pounce and infect your plant in the spring.” 

This is why it is important not to put fallen leaves in your compost in spring, as they can infect your whole garden. If you plan on pruning your roses, then always gather up the leftover foliage and properly dispose of it by placing it in the bin.

Mulch your roses in March 

One of the most important jobs for roses in March is to make sure they are mulched, which is the garden practice of putting a layer of organic material such as straw, compost, or bark around your plants. 

Louise said: “In March, put a thick layer of mulch (one to two inches deep) around the base of your roses. 

“I do this every year. Indeed, it’s one of my top gardening jobs for March. This gives the roses a nutritional boost, keeps weeds at bay and helps retain moisture for them.”

Mulching roses prevents too much rain from gathering at the base of your plant, which prevents the water from splashing the spores onto the plant. 

It is a simple and natural way to give roses energy to help keep them healthy, and it also acts as a barrier to prevent them from becoming infected.

Feed your roses properly 

Roses can be fertilised once the weather is consistently warm, as this means they can begin growing and are storing energy to start flower production. 

Louise said: “It makes a lot of sense that feed will be a key weapon in your fight against black spot. After all, like humans, the healthier roses are, the better equipped they will be to fight off diseases such as black spot.”

If you want to encourage bigger and more abundant flowers, the best time to feed roses is usually late March to early April.

According to Louise, a “magical” way to prevent black spots is feeding your flowers Uncle Tom, a natural rose tonic that you mix with water and give your roses every seven to 14 days during their growing season. 

Louise said: “It comes in a funny looking bottle and a little goes a very long way! You just add 10ml to one litre of water and drench the soil around your poorly rose to give it a boost.”

If you take the time to do these easy tasks now, your roses will stay healthy and look brilliant for the rest of the year. Black spot disease will make it much harder to exist in your garden.