Gardening Q&As March 2007
Award-winning gardening writer, Val Bourne, provides answers to a few common dilemmas 1. Why does my compost heap turn into black treacle?Compost heaps should be like a multilayered sandwich with lots of spaces between layers of stems, leaves and roots. But all too often they are weighed down with soggy grass clippings.
The following technique can help. Place any clippings on a plastic sheet or tarpaulin after mowing and leave them for a day before turning them. Leave them for another day and by then your heap should have changed from a green, soft pile into a dull-brown, drier one.
These brown clippings have partially rotted down and will smell slightly sweet. You can either use them to mulch under shrubs and raspberries, or lay them at the back of the border, or add them to your heap.
Also I recommend a natural accelerator to speed everything up. Comfrey leaves are excellent but do grow an upright, non-spreader like the blue-flowered Symphytum caucasisum or S. ‘Rubrum’.
Chop back the leaves regularly and apply them to your heap. Rabbit and chicken droppings can also be used but dog or cat faeces won’t work! They’re too acid. Keep the heap moist and warm by covering with carpet (face down). Water if too dry.
Create extra air flow by using square wooden bins with gaps between the planks rather than tall plastic ones. If you have space, three is an excellent number. One to rot, one to dig out and one to add to.
Do you have any good composting tips? Share your expertise at the Potting Shed at Saga Zone
2. When I should I prune lavender?It really does depend on which type of lavender you’re growing. English lavender ( Lavandula angustifolia) flowers in early summer and has short stems topped with compact flowers.
These hardy lavenders should have their flowers cut and dried during Wimbledon fortnight and you should prune them back to bare wood in early August. They make good hedging plants and ‘Hidcote’ and ‘Imperial Gem’ are both excellent and can last for 20 years if regularly pruned.
Lavendins, forms of Lavandula x intermedia, are less hardy and they flower later - forming billowing bushes topped with long tapering flower heads.
The mid-blue ‘Seal’ and the dark-purple ‘Grosso’ are typical varieties. These will not stand hard pruning, trim back very lightly in September, hardly cutting into the foliage and aim for a spherical shape. These flow and ebb during summer and lavenders have a strong winter presence too but they can become woody after five or ten years - so do take summer cuttings.
French lavenders are the least tough of all and as a result they are pruned very lightly in midsummer after their main flush of flower. You shear off the flower stalks and a little of the foliage - never cut them hard back. They have an upright shape and they only last five years -but those early flowers with their flag-like top petals symbolise early summer. Lavandula pedunculata subsp. pedunculata can’t be beaten.
Whichever you grow sun and excellent drainage are vital requirements for these bee magnets.
Have you a favourite variety? Share your passion at Saga Zone's Potting Shed
This article was created: 5 February 2007.
This article was last edited: 28 February 2007.
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