If you're having trouble reading this from your email, click here to access it through your internet browser.

Oak Leaf Gardening Monthly Cuttings
Newsletter 11 - April 2012
What to do now

Ornamental plants

  • Give your beds and borders a feed, particularly around roses, spring bulbs and young shrubs/trees. Remember that acid loving plants will need an ericaceous feed.
  • Plant new perennials and finish off dividing summer flowering ones (eg delphiniums).
  • Carry on sowing hardy annuals outside and planting out ones sown in the autumn.
  • Think about how you're going to support taller herbaceous perennials and start to put the supports in place as the new growth comes through.
  • Deadhead your spring bulbs regularly. Cut back the foliage six weeks after the flowers have died down.
  • Climbers and wall trained shrubs will be starting to shoot, so keep on top of tying them into their supports. Climbing rose stems should be tied in horizontally to get the best display.
  • Prune winter flowering jasmines, hydrangeas, forsythias and flowering currants.
  • If you’re running late with your rose pruning make sure you get it done before the middle of this month.
  • Watch out for plain coloured leaves on variegated plants; immediately remove the shoots bearing them.
  • Remove the tatty old leaves from ferns and mulch them well.
  • Start to get rid of your winter bedding to make space for next month's plantings.
  • Now's a good time to plant or move evergreen shrubs and trees (including planting new evergreen hedges).
  • Plant out, or harden off, pots of dahlias, gladioli, calla lilies, arisaemas and tuberous begonias towards the end of the month when the risk of frost has passed.
  • If you have the space, you can pot up summer containers and hanging baskets and keep them in the greenhouse ready to harden them off from the middle of next month.
  • Take stem cuttings from pot grown hydrangeas and Cape primroses (Streptocarpus).
Fruit and veg
  • Outside it's time to sow broad beans, summer cabbages, Brussels sprouts, early peas, calabrese, cauliflowers, sprouting broccoli, mizuna, leeks, beetroot, radishes, spring onions, sugar snap peas, mangetout, lettuces, rocket, turnips, kohlrabi, spinach, parsnips, Swiss chard, chicory, endives, carrots, onions and hardy herbs including parsley, chervil, fennel, dill and marjoram.
  • Plant first early, second early and maincrop potatoes this month. Make sure the new shoots are covered with earth to protect them from frost.
  • Onion sets, shallot sets, asparagus crowns and globe/Jerusalem artichokes can also be planted this month.
  • Harvest the first overwintered spring onions and the last of the sprouting broccoli and Swiss chard.
  • Harvest forced rhubarb when it’s ready.
  • Keep weeding your veg patch so seedlings aren't overwhelmed by weeds.
  • Plant strawberries, figs and grapevines.
  • Tie in new stems on cane fruits such as raspberries.
  • In the greenhouse you can sow tomatoes, melons, cucumbers, sweetcorn, basil, coriander, aubergines, peppers, okra, squashes and courgettes.
  • Have fleece or old net curtains ready to throw over blossom if there’s a late frost.
General tasks
  • Mow your lawn fortnightly, or weekly if the weather is mild and it's growing quicker than normal.
  • Give your lawn a feed, though you may want to leave it until early May if you live in colder regions. You can also re-seed any dead patches in the lawn.
  • It's the start of the weeding season; removing weeds from borders now will stop them self seeding and causing a bigger problem later in the year.
  • If you have slug/snail defences get them in place early this month!
  • Remove suckers from trees and shrubs, tearing rather than cutting them off to prevent re-growth.
  • Purchase and pot up plug plants for summer ornamentals and vegetables.
  • Ventilate your greenhouse on warm days in the morning, but shut them up again by mid afternoon to build up a bit of heat for overnight.
  • Make sure you keep up with thinning out, pricking out, potting up and potting on your seedlings.
  • Towards the end of April, unless the weather is unseasonably cold, you can start to harden off tender ornamental plants and greenhouse raised vegetables.
  • Take advantage of warm days to stain woodwork in the garden, particularly where it will be covered with plants later in the year.
Pulmonaria 'Sissinghurst WhitePlant of the month

Commonly known as 'lungwort', Pulmonaria 'Sissinghurst White' is a low growing, deciduous perennial whose white spotted leaves provide excellent ground cover from spring to autumn. In the spring pink buds open into pretty, funnel shaped flowers.

The plants benefit from being divided every few years after flowering. Water well in dry conditions to prevent powdery mildew.

Find out more...

Problem of the monthFlea beetle damage

Flea Beetle adults overwinter in plant debris and emerge around now to start feeding. You can spot their presence by the small, round holes or pits they make in young leaves. The holes are usually just 2 to 3mm across.

At this time of year they can be particularly troublesome in the veg patch, affecting rocket, turnips, radishes and some brassicas (including stocks and wallflowers).

Clear debris away in the autumn and water seedlings well in spring to promote rapid growth before the beetles can do too much damage. Severe attacks can be dealt with using an insecticide.

Find out more...

In the news

Drought latest

With hosepipe bans due to be introduced in Southern and Eastern England on April 5th, around 20% of homeowners claim, in a B&Q survey, that they will still use hosepipes. 85% stated that they would not report neighbours for doing so.

Several of the previous exemptions to the ban, such as for newly laid turf, have now been removed, leaving many gardeners in a tricky situation. However, drip or trickle systems are still allowed. The sales of water butts have almost doubled on this time last year as a result of the early ban.

Alan Titchmarsh has called the water authorities' tendency to blame gardeners for droughts 'bonkers' and criticised the high fines levied against gardeners flaunting the ban.

Please refer to your local water authority for details of bans and exemptions in your area.

Increasing allotments...and the cost

As the demand for allotments continues to rise, two-thirds of councils will increase the availability of allotment spaces this year. However, in order to reduce the cost of subsidising plots, 54% of councils also intend to increase charges.

1 million down, 5 million to go!

The Woodland Trust have so far planted 1 million of the 6 million trees they aim to plant to celebrate the Queen's Diamond Jubilee. The Queen herself, as well as celebrities such as Dame Judi Dench and the Blue Peter team, have picked up a spade to help with the planting.

Gardening benefits schoolchildren

As the gardening industry continues to call for horticulture to be included in school curriculums, a government taskforce has found that food growing can help children to achieve more across their studies (particularly in sciences), build life skills and enhance their health and well-being.

Asian longhorn beetle found in UK

This dangerous pest has been found in the UK for the first time; in a poplar tree in Kent. FERA and the Forestry Commission are taking urgent steps to eradicate this outbreak. The beetles feed inside trees and can seriously weaken or kill them. They pose a serious threat to trees and shrubs such as maples, elms, horse chestnuts, willows, poplars, birches and some fruit trees.

Inaugural Garden Re-Leaf day a success

March's first ever Garden Re-Leaf day has succeeded in raising tens of thousands of pounds for the Greenfingers gardening charity. Events around the country brought in donations and also engaged with gardeners of all ages and levels of experience.


Weed-beating plants

CrocosmiaAs we move further into spring you're probably finding plenty of weeds 'springing' up in your borders. While mulching is a great way of keeping these little blighters at bay, using ground cover plants can be a more attractive and, in the long run, cheaper way of keeping your beds and borders free of these invaders.

Most people consider ground cover to be low growing, evergreen plants. While these are certainly effective ground cover solutions, there is so much more you can use.

Firstly, let's consider the 'evergreen' element. Deciduous plants generally won't provide much interest over the winter months, but they can still be useful ground cover solutions as weeds are usually also dormant over the winter. So long as you choose vigorous deciduous plants they'll do as good a job of stifling the growth of weeds as evergreen alternatives.

Secondly, does ground cover have to mean 'low'? If you're looking for something to edge your border then the answer is probably "yes", as you don't want the plants further back to be hidden by your ground cover choice. However, in many situations taller ground cover can be both an attractive and practical solution. Consider spaces under trees, for example. In this situation a taller ground cover can add interest to what would otherwise be a bare trunk.

Here are a few ideas for ground cover which don't meet the traditional 'low and evergreen' premise, but which are still attractive and useful solutions:

Alchemilla mollis, otherwise known as lady's mantle, grows to 50cm tall and produces clumps of pretty, rounded leaves from spring to autumn with sprays of yellow flowers in summer (which can be trimmed back to avoid self seeding).

Crocosmia (montbretia) produce vigorous, blade-shaped foliage from early spring and flower in summer, growing to around 1m in height. Crocosmia x crocosmiflora 'George Davison' is shown above.

Hostas come in a wide range of sizes and all have large leaves which will provide excellent ground cover, particularly useful for shady spots.

Dicentra spectabilis is a deciduous, herbaceous perennial which grows to 1.2m tall and is useful as ground cover in shady conditions, where it will still produce its arching stems dripping with heart-shaped flowers in spring.

Pulmonaria cultivars such as P. 'Sissinghurst White' (featured above) are deciduous, shade liking, relatively low growing (from 20 to 40cm) and have large leaves providing good ground coverage from spring to autumn.

Rodgersia pinnata 'Superba' grows to 1m tall, bears fluffy pink flowers in summer and is good for moist to boggy conditions in either sunny or shady sites.

Rosa 'Surrey' is one of several rose cultivars grown specifically for ground cover, this one reaching up to 80cm in height and bearing pink flowers in summer and autumn before losing its leaves.

More ground cover suggestions...


What's on this month

April is full to bursting with great garden events to visit, here are just a few of them:

  • 6th to 9th April - Suffolk Spring Garden Show, Ipswich, Suffolk.
  • 8th & 9th April - Plant Hunters' Fair, The Dorothy Clive Gardens, Market Drayton, Shropshire.
  • 10th & 11th April - Great London Plant Fair, RHS Horticultural Halls, London.
  • 11th April - 'Champion trees' guided walk, Castle Kennedy Gardens, Rephad, Stranraer, Wigtownshire.
  • 14th & 15th April - Spring Gardening Show, Capel Manor Gardens, Enfield, Middlesex.
  • 16th to 22nd April - RHS National Gardening Week, events around the UK.
  • 17th April - 'Perfect posture: a guide to plant supports', RHS Wisley, Surrey.
  • 20th to 22nd April - RHS Show Cardiff, Cardiff Castle, Cardiff.
  • 21st April - Composting advice, Ryton Gardens, Coventry.
  • 22nd April - 'Growing through sound' one day course, Royal Botanic Garden Edinburgh.
  • 26th to 29th April - Harrogate Flower Show, Harrogate, North Yorkshire.