Your Garden In March

Although winter’s icy fingers cling to March, their grip weakens daily. The weather may not always be clement, but there’s no turning back now. What I love most about March is watching how nature responds to changes in temperature. A warm spell will propel spring bulbs into rapid growth, but the moment the mercury drops, they stop still, as if they were playing a game of musical statues. This is how plants protect themselves, preserving their energies until the weather is fine and pollinators are abroad.

For the keen gardener, March is a ‘reap what you sow’ month. By that, I mean that any preparation you can do in the garden this month will pay dividends later. Tasks such as aerating lawns, dividing perennials, feeding, and mulching are far from glamorous, nor are their results immediate, but they will make a noticeable difference later on. If February has been frosty or foul, then March is also an excellent time to finish any winter pruning and tidying.

If you’re a fledgling gardener, focus on two things this month – feeding and planting. When plants are not growing, they don’t require much food. However, the rain has steadily leached nutrients from your soil through the winter. As the weather improves and before growth begins again, adding goodness back in is essential, using bulky fertilisers such as horse manure, garden compost or granular feeds such as chicken manure pellets and blood, fish and fish and bone. Attention to feeding is even more critical if you garden in containers, as these restrict a plant’s ability to put out roots to find food. Different plants respond better to different fertilisers. Acid-loving plants, such as camellias and rhododendrons, must have ‘ericaceous’ food. (In one of those quirks of branding, ericaceous plant food is always packaged in either fuchsia-pink or purple bottles and boxes – don’t ask me why!)

March is the time to sow or plant anything considered ‘hardy’ (generally tolerant of sub-zero temperatures here in the UK). Exact times will vary from the south to the north of the country, but at some point this month, the ground should be warm and workable enough to welcome new plants. Don’t be in too much haste to sow tender or ‘half hardy’ plants (not tolerant of sub-zero temperatures) unless you have somewhere frost-free to keep them growing happily for another 6-8 weeks. Books, garden centres and social media accounts will have you thinking that you must sow seeds now, but without heat and good light, you are better off waiting until the end of the month, or April. If you’re not convinced, do a little experiment and sow half a packet of seeds now and the other half in 4 weeks. By June, I doubt you’d notice a difference in the size of the plants.

There will be warm, beautiful days ahead; enjoy them, but don’t let a few fine days fool you into believing summer has come early. Frost or snow is still a genuine possibility and this has the potential to undo all your hard work.

March At a Glance

Plan – summer bedding displays and the layout of your vegetable garden for the year ahead. Make a note of your favourite flowering bulbs so that you can order more when the catalogues arrive in May.

Sow – Indoors – hardy annuals early in the month, half-hardy annuals towards the middle or end of the month. Outdoors – hardy annuals, beetroot, broad beans, radishes, spinach, peas, onions, carrots and parsnips.

Plant – Bare-rooted trees and shrubs, container-grown perennials, spring bedding, snowdrops in the green, dahlia tubers in pots or crates. Early-cropping potatoes, onions, and bare-rooted asparagus crowns.

Prune – dogwoods, willows, roses, clematis and anything that needs gentle re-shaping.

Feed – acid-loving plants (camellias, rhododendrons, azaleas and heather), fruit trees, blackcurrants, brassicas and house plants.

Harvest – daffodils, anemones, hellebores, flowering branches of daphne and cherry, cauliflower, kale, leeks, parsnips, celeriac, swede, spinach, spring cabbage.

Buy – bare-rooted plants, peat-free seed compost, seeds, dahlia tubers, gladioli corms, lily bulbs, spring bedding plants, alpines, new garden furniture, plant supports.

Enjoy – bright sunny days, birdsong, the changing of the clocks leading to longer evenings, Mothers’ Day celebrations and Easter preparations.

Visit – gardens with good collections of daffodils and spring-flowering shrubs. Some hold special daffodil festivals.

Further Advice From Dan Cooper Garden

Every day in March brings new wonders. If you spend a few days away from home, you will notice big changes on your return. If you’re feeling full of the joys of spring, here are a few things to be getting on with:

Indoors

Now that light levels are higher, you can resume feeding houseplants with a dilute fertiliser once a week. When you buy a new plant, the compost should have enough nutrients to nourish it for 6-8 weeks. After that, they’ll benefit from a weekly boost. Feeding requires minimal effort, and you will soon notice the difference from only watered plants. Special formulations are available for citrus fruits, orchids and Cape primroses (Streptocarpus). Use these if you can; otherwise a general-purpose houseplant food will do just fine.
If you’ve brought potted daffodils and hyacinths indoors to bloom, you can choose what to do when the flowers fade. The bulbs will have put all their energy into producing blooms, so if you want them to flower again, they need to recharge first. Plant them out in the garden, deeper than in the pot, so they’re not close to the soil surface. Remove dead flowers but never the foliage: leaves act as a plant’s solar panel, allowing the bulb to regenerate. It’s unlikely that your bulbs will flower as prolifically again next year, but their flower power will be fully restored over a couple of seasons. If you’re too impatient or have no space, you may find that someone with a garden will take spent bulbs off your hands. Failing that, compost them.
When buying plants during the cooler months, take care when transporting them home. Many of the plants we cherish as house plants come from the tropics where temperatures are high and fairly constant; they may not take kindly to being left in a car or walked home in a chilly wind. Ensure the shop wraps your plant thoroughly, protecting it from top to bottom, and take it straight home. I would avoid ordering plants online if you know it will be cold for a few days – good companies won’t send out stock in these conditions, but it’s better to be safe than sorry. Beware house plants displayed in shop doorways or out on the street. They may have caught a fatal chill before you even set eyes on them.

Alpinia zerumbet ‘Variegata’ is a wonderful house plant

Potting Shed & Greenhouse

If you have space in a light, frost-free environment you can start planting dahlias in pots now. If you only have a few, plant them in moist compost in individual pots, taking care not to break off any of the fleshy tubers – these will fuel the growth of new shoots. If you have lots of tubers, these can be planted on mass in trays or crates until they are ready to be planted out in May. The tubers should sit just beneath the surface of the compost. Only water your dahlias when shoots start to appear. If you don’t have space indoors, keep your tubers somewhere cool (not cold), dry and dark and plant them directly in the garden in May. They will soon catch up, but you’ll need to be on the watch for snails and slugs night and day.
If the weather is fine, give your greenhouse its annual clean. Scrub down wood and metal surfaces with a weak eco-friendly disinfectant, take down any winter insulation and wipe the glass to maximise the light reaching your plants. There’s nothing like being warm and toasty under glass when it’s still nippy outside. As well as being more comfortable, a warm day will allow you to move any resident plants out during the day so that you can get on unhindered.
Repot overwintered cannas in fresh compost with an added slow-release fertiliser. If they have become large and congested, cannas can easily be divided using an old saw or breadknife. Take care not to damage any new shoots. Water and place them in a warm, light spot to encourage them back into growth.
On sunny days your greenhouse will warm up very quickly. Keep windows and doors ajar to moderate the temperature and circulate fresh air.

Terrace & Balcony

Take advantage of good weather this month to have lunch outside or enjoy your first barbecue of the year. If you protect your garden furniture using covers, remove them on a mild, sunny day and give each piece a thorough going over with a stiff brush. If you find cobwebs, dirt, algae or rust stains, scrub the furniture with warm, soapy water and let it dry naturally in the sun. Wait to replace the covers until completely dry.
If you have painted furniture, planters, fences or trellises that are flaking and need attention, seize any opportunity to sand them back and give them a fresh coat of good quality exterior paint. Once plants start growing again, this is a much trickier job. The weather must be fine and dry, so have all the materials you need ready and wait for that eventuality.
Whilst you’re in the mood for sprucing things up, jetwash decks and patios, avoiding any nasty chemicals that might wash into the ground. Dirt, algae, and moss build up quickly over winter. They can make smoother surfaces like slate dangerously slippery when wet, but they might form a pleasing patina in other situations. Don’t be in too much haste to get everything spotless.
If they’ve not been put away clean and dry in autumn, barbecues might need sanitising before being used again. If you are cooking on gas, light your barbecue and let it get nice and hot to burn away harmful bacteria. Before it’s completely cool, use a wire brush or specially designed barbecue brush to remove any residue.

Tulipa greigii (cultivar unknown) is an early bloomer.

Flower Garden

After three or four years, most perennial flowering plants will benefit from lifting and dividing. The younger portions of the plant on the outside edge of the clump tend to be more vigorous and should be replanted. After lifting the rootball using a spade or fork, you can be reasonably brutal and cut the plant into chunks using a sharp spade, old saw, hori hori or breadknife. Just ensure each section has roots and shoots. Replant at the same level and water well to encourage root development.
One of my guiding principles is to stake early and stake well. I hate to see plant supports. The best way to hide them is to get them in the ground before a plant starts growing. New shoots will disguise any ugly engineering and be both supported and natural in shape. There’s nothing more unsightly than tall plants bundled and tethered to bright-yellow bamboo canes – hazel branches, birch twigs, or iron supports with a rusty finish are more discreet.
If you are a confident, experienced or adventurous gardener, you can take chrysanthemum, delphinium, phlox and dahlia cuttings. Remove new shoots from the crown (where they meet the ground in the centre of the plant) using a clean, sharp knife and pop them around the edge of a pot filled with gritty, peat-free compost. Give your cuttings warmth to encourage roots to form and resist the urge to keep checking for progress. Once they produce new growth and roots appear from the bottom of the pot or tray, they are ready to be moved into individual pots.
You can sow hardy annuals such as nasturtiums, love-in-a-mist (Nigella) cornflowers, poppies and calendulas outside towards the end of the month. You can plant them in shallow drills (furrows) where you want them to grow. If these pretty plants already inhabit your garden, you’ll already have self-sown plants popping up all over the place. Thinning them out will produce bigger, stronger, longer-flowering plants.
You can still prune roses and late-flowering clematis in early March. Leave it any later, and they will have started to produce new shoots. Have a look at February’s post for more advice.
Spring has only just begun, so keep deadheading pansies, violas, primulas and cyclamen to keep flowers coming for another month or two. You should deadhead daffodils immediately the flowers fade – just pulling the flower from the top of the stem is perfectly adequate. Wear gloves or wash your hands afterwards, as the sap from daffodils can irritate your skin.
Slugs and snails will dine on plump new shoots emerging from the ground. They are particularly partial to hostas, dahlias, lupins, delphiniums and numerous other garden treasures. I will pass no judgement on your preferred method of ridding your garden of these annoying pests; just ensure you act before any great harm is done. Deterrents include copper tape, fine grit, broken shells, sheep’s wool, beer traps, relocation – aerial or otherwise – and, if needs must, slug pellets. If using the latter, it’s a case of the fewer, the better. Giving slugs and snails the blue carpet treatment is a waste of money. It looks hideous and is bad news for the environment.

Primula ‘Amethyst Cowichan Group’ can be grown from seed

Kitchen Garden & Allotment

Alas, it’s not just the plants we have chosen for our gardens that respond to warmer weather. Weeds will now start to take advantage of improving conditions. Many plants we classify as weeds are programmed to live fast and die young, some with lifecycles that might only be a few months long. Whilst it’s important to keep on top of your weeds, make sure you know what’s what before yanking things out. Among the weeds could be seedlings of desirable plants. If in doubt, leave well alone and see what you get. Choose a day when the soil surface is relatively dry to use a hoe. The uprooted weed seedlings will dry out on the soil surface rather than re-rooting. Use a dandelion weeder to remove weeds with long tap roots, as severing their heads will not be enough to kill them.
Sow carrots and parsnips outside this month. Carrots need protection from carrot root fly, so they should be protected with a cloche or fleece or be sown in an elevated container. Our allotment neighbours plant them in old wheelbarrows or plastic compost bins. Parsnips germinate slowly and erratically; sowing them as soon as the soil warms up ensures they get the long growing season needed.
You can start onion sets in trays divided into modules. Although they don’t need heat, this is an excellent way to get them going. Out in the open, they sometimes get pulled out of the ground and scattered about by birds and squirrels – I never quite catch the culprits in action!
Pigeons will have a field day if you leave cabbages, purple sprouting, cauliflowers and other brassicas unnetted. I am not a fan of plots covered in netting or cages but sometimes needs must.
Purple sprouting and cauliflowers need harvesting regularly. If you have more crops than you can eat, blanch and freeze them for later in the year.
Established crowns of rhubarb will be growing away strongly now. Unless you are forcing some stems, it’s still too early to harvest. Mulch with well-rotted farmyard manure and leave the plants to develop for another 6-8 weeks.
Asparagus is one of the most desirable vegetables you can grow. It takes up a lot of space and is unproductive for eleven months of the year. If space isn’t an issue and you have a hankering for tender spears dripping in melter butter or Hollandaise sauce, now is the time to plant bare-rooted crowns in a sunny, well-drained spot. You won’t be able to harvest your asparagus for another 2-3 years, but after that, you’ll have a reliable supply for around 20 years.
Feed fruit trees to promote bountiful blossoms and strong new growth. A healthy, well-fed plant is generally more resistant to pests and diseases than a weak, under-nourished one.

Tilia platyphyllos ‘Rubra’ as a pleached hedge.

Wildlife Garden

As the weather improves, many wildlife species begin their breeding cycles. Mammals such as foxes and badgers may be out of sight, giving birth to their young. Birds will be busy looking for nesting sites and building materials. They can be very resourceful, collecting dried grasses and leaves, twigs, tree bark, feathers, moss, wool and woodshavings. If you want to help them out, don’t be too tidy: leave little piles of debris around for them to rummage through. Watching them choose which materials to use can be great fun.
Give hedges and dense shrubs a wide berth to avoid disturbing birds as they build and lay their first clutch of eggs. Some species, such as blackbirds, are more tolerant of humans at close quarters, but give them as much space as you can. It’s not too late to mount bird boxes – just ensure they’re situated where cats can’t reach them.
Continue feeding birds with high-energy seeds, soft fats and grated cheese but not peanuts and bread, as these are too bulky for baby birds and may harm them. There are mixed views about how long one should continue feeding birds, but I feel that as long as you are consistent, it’s okay.
Yellow flowers act as beacons for insects emerging from hibernation; that’s why there are so many in the spring garden. Celandines, daffodils, primroses, forsythia and later dandelions, Kerria, buttercups and marsh marigolds are a welcome sight for us all.
Now is the time to build a new pond or wetland area. You’ll need an open site and the ability to dig to at least 80cm to make a pond deep enough to be healthy and sustainable.
Frogspawn will start to appear in established ponds. Avoid disturbing it, but engage your children in the frogs’ unique lifecycle. It’s one of my favourite things. Do it safely, making sure children are well supervised.