They might come back every year, but knowing what to do with perennials in March will have them off to a strong start for the growing season ahead.
If you’re looking for jobs to do in the garden in March, perennials are a brilliant place to start. Whether you aim to protect them, give them a boost or multiply your collection, you can get started with the key tasks now.
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What you’ll need
Spear & Jackson
Razorsharp Advantage Bypass Secateurs
VLYHGO
Plant Supports (6-Pack)
A handy pack of plant supports
Miracle-Gro
Continuous Release All Purpose Plant Food
This highly rated plant fertiliser will give your perennials a boost.
1. Feed them
As our gardens exit their period of winter dormancy, a dose of fertiliser can help them bounce back into form. Just as it’s important to know when to fertilise roses, feeding your perennials is one of the best things you can do for them in March.
Mulching is one of the most popular methods – a layer of compost or well-rotted manure can enrich the soil, retain soil moisture and even suppress weeds – but you could also use a ready-made fertiliser like Miracle-Gro Continuous Release All Purpose Plant Food from Amazon.
‘Now is a good time to apply a slow-release fertiliser around your perennials to get them off to a strong start,’ says Fothergill’s senior horticultural content manager, Pim Dickson. ‘This is also best done before you add a mulch, such as compost, well-rotted leaves, bark, or straw.’
RocketGro Peat-Free Organic Magic Mulch, which you can also order from Amazon, is ideal for adding nutrients to the soil.
According to gardening and greenhouse expert Lucie Bradley from Easy Garden Irrigation, ‘Astilbes, delphiniums, daylilies, phlox and hardy geraniums are just a few of the ‘greedy’ feeders which will benefit from this early boost of nutrients.’
2. Tidy them up
It’s wise to stay wary of early spring frosts, but you can start to tidy up your perennials in March as new growth begins – both for an aesthetic boost and the chance to give your plants space for light, ventilation, and fresh growth.
‘This means you should be cutting back old stems from bee balm, rudbeckia and sedum as well as old, dead foliage from dianthus, hostas and shasta daisies,’ says Lucie.
‘Removing this debris not only provides room for new growth, but it also reduces the opportunity for fungal diseases, which thrive on old foliage and in moist environments.’
You’ll need to figure out the best secateurs for the job at hand. A pair of garden snips like these Kent & Stowe Garden Life Snips from Amazon are ideal for light tidying. For woodier perennials, anvil secateurs like the Spear & Jackson Razorsharp Geared Anvil Secateurs are a better choice.
3. Protect them
Sadly, many perennials are favoured by pests, too – slugs adore hostas, for example – and even if you know what to do with perennials in March, those efforts can go to waste if the critters get there first. That’s why it’s wise to figure out the best ways to get rid of slugs and other common garden plant pests sooner rather than later.
‘With warmer weather and higher moisture levels, slugs and snails will quickly start to appear in March, emerging from hibernation and actively seeking out food, which makes your perennials (which are putting on new shoots and emerging from the ground) vulnerable to damage,’ Lucie warns.
I tend to find that copper tape like this from Amazon creates a protective barrier around my potted plants, but there are plenty of other ways to deter slugs.
‘You could also place slug traps, either traditional beer traps or traps using over-turned orange and grapefruit skins, near your vulnerable perennials to distract and trap these unwanted pests,’ Lucie adds.
4. Support them
Pest protection isn’t the only way you can aid your perennials in March – taller varieties like hollyhocks and delphiniums will benefit from physical plant supports, too.
‘It is good to set up plant support before they grow too tall,’ says Pim from Fothergill’s. ‘It is easier to access the flower beds, and it won’t set the plants back too much at this stage if you happen to damage a few roots pushing the support into the ground around the plant.’
Lucie also recommends supporting perennials with heavier blooms that can drag the plants over, like peonies and oriental poppies. There are plenty of brilliant plant supports you can buy in-store or online, such as this pack of three bamboo hoop plant supports for just £4 from B&Q.
Or, try this pack of four metal plant supports from Amazon.
5. Lift and divide them
There are so many perennials you can divide in March to multiply your collection of plants and fill your garden for free – especially if you missed the task last autumn. Lucie recommends diving perennials like hostas and daylilies now to prevent overcrowding and encourage strong, new growth.
‘If your clumps of perennials have spread out a bit too much, or you want to add more of them somewhere else in the garden, you can divide them,’ says Pim. ‘Just carefully dig up the plants with as much root as possible, then split the root ball into good-sized pieces using a spade or a serrated knife (I use an old bread knife for this, which is ideal).
You could even buy a dedicated horticultural knife, like the Niwaki Hori Hori Pro.
‘Then, replant some back in place, and others in parts where you want them to grow,’ Pim adds.
Speaking of planting…
6. Plant them!
If you’re keen to expand your collection of garden plants, you’re in luck: there are a huge number of perennials you can plant in March, according to gardening expert Paul Parker, from plants and bulbs specialists J. Parker’s.
‘There’s plenty of planting that can begin in March, including getting any loose-root perennial plants, such as agapanthus, geraniums or irises in the ground,’ he says. ‘If you have loose-rooted plants, remember to soak the roots in water for 24 hours to rehydrate the plant and prepare it to go into the ground. After your plants have had a well-needed drink, they are ready to be planted out in the garden.’
It’s worth keeping a few outdoor plant covers to hand just in case any early spring frosts strike. These plant frost jackets from Amazon are ideal.
Knowing what to do with perennials in March can make all the difference to the displays that follow over the rest of the year.
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