Oak Leaf Gardening Monthly Cuttings
Newsletter 23 - April 2013
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.
  • 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.
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.
  • Keep weeding your veg patch so seedlings aren't overwhelmed by weeds.
  • Plant strawberries, figs and grapevines.
  • In the greenhouse you can sow tomatoes, melons, cucumbers, sweetcorn, basil, coriander, aubergines, peppers, okra, squashes and courgettes.
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!
  • 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.
Camellia japonica 'Nuccio's Cameo'Plant of the month

Camellia japonica 'Nuccio's Cameo' forms a compact shrub growing to about 3m height. In spring it's adorned with delicate pink flowers against a backdrop of dark green, glossy, evergreen leaves. It was developed in the seventies by Nuccio's Nursery in California, USA. Find out more...

Problem of the monthLily beetle

If you grow lilies or fritilleries then you should be on the look out for lily beetles, which can completely defoliate plants. The adults are bright red and up to 8mm in length. They lay orange, sausage-shaped eggs on the underside of leaves. The emerging larvae are reddish-orange and covered in black slime. Check plants regularly. Remove and destroy any eggs, larvae or adults. Contact insecticides are also useful if used early enough. Find out more...

In the news

Ash dieback brings out the cowboys

Trading Standards' officers have warned that rogue tree surgeons are encouraging homeowners to fell ash trees in the wake of the die back disease publicity. Homeowners should be wary of anyone knocking on the door and claiming that a tree has the disease. The current advice is that mature trees which are affected should not be felled. Meanwhile Defra have published their plan for dealing with the disease, focussing on controlling the spread and identifying resistant trees.

Chelsea preview

Here are just a few of the delights waiting for visitors at next month's RHS Chelsea Flower Show:

  • 3 RHS-funded displays by up and coming horticulturalists who have won a nationwide competition for the opportunity to show their potential.
  • A water feature created entirely from leather, thanks to London handbag designer Susannah Hunter, will be part of the Massachusetts Garden.
  • Anacamptis morio, the green-winged orchid, will be showcased in Robert Myer's design for the Brewin Dolphin garden. This native orchid is very rare and will be one of many native British plants used in the garden.

Elsewhere in London the South Bank Centre will benefit from a £120m overhaul, to be finished by 2017, which will include rooftop gardens and plantings to rejuvenate the outdoor spaces in the complex.

Green noise barriers

A plant-based acoustic barrier is being promoted to reduce noise from roads. The 'Kokowall' barrier is made from recycled-plastic tubes covered in coir and planted with climbers. It's aimed at motorways, schools and domestic markets. The green barrier is claimed to reduce an 80db motorway to 30db, the level of a quiet dishwasher.

Glasgow and Bristol vie to be greenest city

Bristol and Glasgow are two of the four cities to have reached the final of the 2015 European Green Capital competition, which judges recreational areas and parks, as well as transport, energy, waste and housing. The winning city will be announced in the summer.


Are your plants hungry?

The world of plant feeds can be confusing, with seemingly no end to the different types of fertiliser available and different ways to apply them. While plants can often obtain enough nutrients from the soil, some soils are less fertile or not suited to specific plants so additional feeding is needed. When plants are grown in containers feeding becomes even more important. There are three things to consider when feeding plants:

  1. What nutrients you want to provide
  2. How quickly you want the nutrients to be released
  3. How you want to apply the feed

1. What nutrients you want to provide

Plants need a wide range of nutrients, all of which are critical to the plant's survival albeit in varying quantities. Most fertilisers focus on providing nitrogen, phosphorous and potassium, which are the nutrients plants need the most of (after oxygen, carbon and hydrogen, which they obtain from the air and water). A 'balanced' fertiliser will contain equal parts of these three elements, often expressed as "NPK 1-1-1". Where they have more of one of the nutrients, such as nitrogen, these proportions will be indicated, eg "NPK 3-1-1". Most general use fertilisers will also provide a mix of other nutrients, such as calcium, magnesium and sulphur. They are ideal for general purpose use. However, if you want a specific result from your feeding (such as fixing a nutrient deficiency or to encourage blooms at flowering time) then you should look for a fertiliser with a high proportion of the nutrient which will give you those results.

There are 4 main types of fertiliser:

  • Organic fertilisers, derived from living organisms, such as bone meal and dried blood. (Please note that these aren't necessarily suitable for "organic gardening").
  • Inorganic fertilisers, derived from non-living material, such as calcium nitrate or superphosphate.
  • Bulky organic matter, such as compost or farmyard manure, which may provide nutrients, but you can't be sure of how much (or little) it will feed your plants. Organic matter is best used to improve structure rather than as a fertiliser.
  • Green manure, which are plants grown to be dug back into the soil as a form of organic fertiliser.

Organic and inorganic fertilisers are the most common ones used. They will either provide a single nutrient (for example dried blood will only provide nitrogen) while compound fertilisers provide two or more nutrients. If you are looking for a general purpose springtime fertiliser then a compound fertiliser, which provides a good balance of nitrogen, phosphorous and potassium, is usually the best choice.

2. How quickly you want the nutrients to be released

Fertilisers can provide nutrients over different time periods. Quick acting fertilisers dissolve in water and allow the plant to take them up almost immediately (great if you have a plant with a nutrient deficiency), whereas slow release fertilisers break down over a period of time and give the plant a more gradual supply of nutrients over a longer period (ideal for seasonal pot plants).

3. How you want to apply the feed

Your final choice is how to apply the feed to the plant. Base dressing fertilisers are applied when preparing a seed bed or when planting a plant. Top dressing is applied to the surface of the soil where it will dissolve and be carried into the soil by water. Liquid feeds need to be diluted in water (or are purchased ready-diluted) and should be watered over the plant's root zone. Finally, foliar feeds are sprayed onto the leaves and are usually used for quick action to treat a nutrient deficiency.

When measuring out the amount of fertiliser and the area over which to spread it, ensure that you pay close attention to the manufacturer's instructions. Too little feed can mean that your plants don't benefit and too much can do more harm than good.

For more information on fertilising plants please take a look at out our 'How to feed plants' information.


What's on this month

After all the unseasonable weather let's hope for some sunshine so you can get out and enjoy these events:

  • 6th & 7th April - Spring Flower Show, Boconnoc, near Lostwithiel, Cornwall.
  • 12th & 13th April - RHS London Orchid and Botanical Art Show, RHS Horticultural Halls, London.
  • 12th to 14th April - Spring Gardening Show, Capel Manor Gardens, Enfield, Middlesex.
  • 13th & 14th April - Rare Plant and Spring Food Festival, Waddesdon Manor, Aylesbury, Buckinghamshire.
  • 15th to 21st April - National Gardening Week, events around the UK.
  • 19th & 20th April - Woodland/Shade Loving Plants Special Days, Harveys Garden Plants, Thurston, Suffolk.
  • 19th to 21st April - RHS Flower Show Cardiff, Bute Park, Cardiff Castle, Cardiff.
  • 20th April - Plant Identification for Beginners, Ness Botanic Gardens, University of Liverpool, South Wirral.
  • 20th & 21st April - RHS National Rhododendron, Camellis and Magnolia Show, RHS Garden Rosemoor, Great Torrington, Devon.
  • 21st April - Specialist Plant Fair, Spetchley Park Gardens, Spetchley, Worcestershire.
  • 25th to 28th April - Harrogate Flower Show, Great Yorkshire Showground, Harrogate, North Yorkshire.