Gardening in March

Tomatoes are one of the easiest crops to grow. Even if you don’t have a greenhouse, plants will thrive on a sunny patio or balcony. To ensure early crops, sow tomato seed indoors or in a heated greenhouse now. Fill pots or trays with seed and cuttings compost, level the surface and lightly water using tap water. Sow seeds on the surface, 1-2cm apart, then cover with a thin layer of compost and place in a propagator at around 20ºC (68ºF). When seedlings emerge, usually within a fortnight, open ventilators on propagator lids.

A winter build-up of algae can leave timber decking as slippery as an ice rink while looking unsightly. Pressure washing quickly shifts the muck without using chemicals. For best results, wash decking when timber is wet (if the weather is dry, soak the deck using a hose, half an hour before pressure washing). Always use a fan jet nozzle on the lance of the pressure washer – the same nozzle you use for washing a car (never a rotating nozzle which is meant for cleaning paving and can damage wood). Direct water evenly along the timber. Avoid hovering over the same area or you’ll end up with light and dark patches.  Pressure washer accessories, such as the RA 90 surface cleaner in the picture below, can also make the job a lot easier.

How to clean wooden decking >

Daffodils herald the arrival of spring. When flowers go over, cut the flower stalk off at the base – that way, bulbs won’t try to produce seed and energy will be conserved for next year’s flowers. Leave daffodil foliage alone for at least six weeks and don’t cut it off until leaves are yellow and have died down naturally. Bulbs rely on foliage to create energy which is stored to boost flowering next spring – so don’t rush to tidy leaves away.

Shrubs in containers can look sorry for themselves after winter. Often, it’s because reserves of nutrients in compost have become depleted, leading to yellowing leaves and sluggish growth. The problem can easily be rectified without tipping plants out and repotting.

Scrape away the top inch of compost on the surface and replace it with fresh compost, watering well afterwards. For most shrubs, John Innes No. 3 compost is ideal. For acid-loving shrubs such as azalea, camellia and blueberries, top-dress with ericaceous compost.

The first-early potatoes that were chitted (sprouted) indoors during January or February can be planted out in late March if the soil is workable.

Choose a sunny, sheltered location – soil should be well-drained and ideally it should have been dug in autumn and boosted with well-rotted manure. Dig a narrow trench that’s around 12cm/5in deep and space each seed potato about 30cm/12in apart.  Backfill the trench with soil. As plants grow you’ll need to ‘earth-up’ (draw soil up to the stems) which helps to protect from frost and excludes light that can turn potatoes green.

Your home-grown spuds should be ready in June and July.

As temperatures rise, weeds spring up. The key to control is to tackle weeds fast: once they flower and set seed, your problem will become worse. If you’re prepared to use chemicals, choose a systemic weedkiller (such as products containing glyphosate). It’ll travel through the plant and kill the root as well as foliage, preventing re-growth. Spray on a mild day when weeds are actively growing and no rain is forecast. Organic weedkillers are widely available and use natural ingredients to bump-off unwanted invaders. You can also use a hoe or hand-weed but make sure to tease out as many of the roots as possible.

Gardeners often leave last summer’s flower heads on hydrangeas over winter, because they provide a degree of frost protection for emerging buds. Now, to allow for new growth, dead flower heads should be cut off. Use secateurs to cut back to the first good pair of buds below the old flower head. The only exception is the climbing hydrangea, which should be pruned in summer when it has finished flowering.

Slugs come out in force as tender, young shoots emerge in spring. Molluscs become active when warmer weather arrives, so it’s worth stepping up slug patrols. Problematic areas can be protected by placing organic slug pellets, which contain ferric phosphate, on the soil. Physical barriers can be made around plants – packs of granules are available at garden centres that slugs hate slithering across. Slugs can be caught in beer traps, too, which are set in soil and filled with lager, leading gastropods to a tipsy death. Don’t go wasting your finest ales filling them up though; cheap supermarket beer will do the trick.

The brightly coloured stems of dogwoods (Cornus) put on a stunning display all winter. By pruning plants hard while still dormant in late March, before leaves start to appear, it’ll encourage them to put on new growth with extra vigour, leading to a better display of vivid colours next winter. Using sharp secateurs, cut stems down to about 15cm/6in above ground level. Plants will soon bounce back.

Our gardens produce a huge amount of waste – from grass clippings to prunings and spent veg plants. Instead of binning it, composting allows green waste to break down naturally, and the resulting crumbly brown compost can be spread on flower beds and veg patches as an organic soil improver. You can buy compost bins at garden centres, but it’s easy to make your own. Four pallets can be screwed together to make a sturdy frame. If you don’t have pallets, buy four tree stakes, hammer them into the ground then wrap chicken wire around them and secure the wire to the stakes.

There are so many beautiful contenders for the flower of the month for March.  There is, however, one plant that packs such a punch for flower power that it beats its early-season rivals hands down. The star magnolia, Magnolia stellata, emblazoned with its magnificent, dazzling white, star-shaped flowers, is the ultimate wow-factor flower to plant in March. It’s a deciduous specimen shrub that pulls out all the stops to announce that spring has arrived in style!    

The showy flowers of the star magnolia can open to 10cm wide and may occasionally be lightly flushed with pink. The dazzling blooms open well before fresh foliage unfurls, smothering bare stems in a sea of white. While some early spring flowers can be at risk from late frosts, the blooms of Magnolia stellata are more resistant to damage than magnolia varieties that bear goblet-shaped flowers, but frost pockets must be avoided at all costs.

The good news is that you don’t have to own a sizeable garden to enjoy the mass of brilliant white flowers.  The star magnolia is a slow-grower, reaching just two or three metres high and unlikely to spread to more than three metres at maturity, while growing it in a container will restrict its size further and create an ideal specimen patio shrub for gardeners who don’t have enough room in borders.

Magnolia stellata is hardy, so there’s no need to worry about its ability to overwinter, but plants don’t care for exposed sites, so always grow in a location that’s sheltered from cold, drying winds. The protection of a wall or fence can work wonders at providing an extra layer of reassurance if you live in a colder region of the UK. A sunny or part-sunny position is a must, as is well-drained, moisture-retentive soil. Magnolias generally dislike dry soils, so incorporating well-rotted organic matter at planting time is advisable if you garden on light soil. Plants will need to be kept well-watered while they establish, especially during hot summers.

There’s no need for formal pruning: simply remove any damaged, crossing or diseased branches in midsummer. Follow these tips and you’ll have a glorious shrub or small tree that’s the envy of the neighbourhood every spring.

Broad beans are the perfect vegetable to plant in March. They are easy to grow and make an excellent crop for those who are new to kitchen gardening.      

Broad beans grow best in full sun in a sheltered position, preferring to get their roots down into rich, well-drained soil. Digging and improving the soil by adding garden compost or well-rotted manure before sowing will pay dividends, as will warming the soil prior to sowing.

For an early-maturing crop with exceptional flavour, broad bean varieties don’t come more highly recommended than ‘De Monica’, a proven variety for disease-resistance that can be directly sown outdoors from March onwards. If space is at a premium, opt for ‘The Sutton’ which forms bushier, more compact plants while the beans are a distinctive creamy green colour. Another tried-and-tested variety for heavy crops is ‘Imperial Green Longpod’ – its pods can be up to 38cm (15in) long, each containing up to nine large green beans.

Sow seeds around 5cm deep, with rows 22-24cm apart (check the packet for exact spacings of your chosen variety) and support plants using canes and string. Keeping plants well-watered, especially when they begin to flower, is essential, as is carefully hoeing to remove weeds from between rows that will otherwise compete for moisture and nutrients.

One of the most common problems that you’re likely to face during the growing season is blackfly, with these pesky aphids often forming around the tops of plants. They’re partial to the tender tips of broad beans, so pinching out the tips once the lowest truss of flowers has set small pods can help to reduce infestations and encourage more pods.

Looking for a small tree that’s perfect where space is at a premium, and offers interest throughout the year? Commonly known as snowy mespilus or Juneberry, Amelanchier lamarckii flowers reliably early in the season, with its finest hour in March as heads of delicate star-shaped white flowers burst forth.

The snowy mespilus has a reputation as a tree for all seasons, and holds a Royal Horticultural Society Award of Garden Merit (AGM) for top garden performance. Plant it as a specimen tree in full sun or partial shade, in well-drained neutral or acidic soil (avoid chalky soils though) and it’ll grow to no higher than 6 to 10 metres after 20 or so years.