Gardening experts are warning Brits that March is the “last chance” for one key task. By the end of this month, you need to ensure your roses are pruned to keep them happy and healthy, according to the Royal Horticultural Society (RHS).

At this time of year you should also be thinking about planting onions, the charity said. As well as shallots and summer-flowering bulbs.

It explained: "Spring usually starts to arrive across the country in March, and the longer days provide the opportunity for an increasing range of gardening tasks." The organisation added: "It’s time to get busy preparing seed beds and sowing seed, and it’s your last chance to prune roses."

Late winter (from February to March) is apparently the best time for pruning roses. A statement on Gardeners' World also says: "The best time to prune most roses is from late winter to early spring, just around the time new growth starts.

"In the south of the UK, spring growth may start as early as January, while further north you may not see any new leaves until April."

To do this successfully, the RHS issued the following advice:

• Cuts should be no more than 5mm (¼ in) above a bud and should slope downwards away from it, so that water does not collect on the bud. This applies to all cuts, whether removing dead wood, deadheading or annual pruning
• Cut to an outward-facing bud to encourage an open-centred shape. With roses of spreading habit, prune some stems to inward-facing buds to encourage more upright growth
• Cut to the appropriate height, if a dormant bud is not visible
• Cuts must be clean, so keep your secateurs sharp. For larger stems, use loppers or a pruning saw
• Prune dieback to healthy white pith (the white centre of the stems)
• Cut out dead and diseased stems and spindly and crossing stems
• Aim for well-spaced stems that allow free air flow
• On established roses, cut out poorly flowering old wood and saw away old stubs that have failed to produce new shoots
• With the exception of climbing roses and shrub roses, prune all newly planted roses hard to encourage vigorous shoots
• Trace suckers back to the roots from which they grow and pull them away.

It added: “Feed all pruned roses with a general purpose or rose fertiliser in spring. Mulch with garden compost or manure.”

If your roses are climbers, ramblers, or bush varieties, you should consider slightly different pruning steps. The RHS website has more information on pruning these.

While pruning, you should be wary of certain pests and diseases that you may need to deal with. The RHS said: "Wear gloves when handling thorny roses and keep a watch when you are pruning for the following pests or diseases while pruning; rose aphids, rose large sawfly, rose leaf rolling sawfly, rose black spot, rose dieback, rose powdery mildew and rose rust."