Danny Calderbank gets to the root of gardening issues...

Everyone has a favourite hardy perennial; mine is Verbena bonariensis and judging from my mail box and the frequency of this plant’s appearance on TV gardening programmes, I am not alone. The common name of Vervain is not often used but I am sure you will readily recognise the plant. Verbena bonariensis can truly be called an ‘architectural’ plant for it is self supporting and capable of reaching shoulder height. The stems may look delicate but are actually wiry and the long-lasting flowers are plentiful and much loved by bees and butterflies.

In the north plants sometimes struggle to over-winter and I lost all of mine due to the severity of last winter and are now replacing them. Plants are generally available and this is possibly the best way of establishing Verbena in the garden although they can be relatively expensive. An alternative is to sow seed although I had little success with this method for many years because I was sowing too early and not providing the correct conditions for germination. From an early sowing from February to April they will flower in the same year. Seed is available from Thompson and Morgan and must be sown on the surface of the compost for they need light to aid germination and a temperature of 24 -27 °C needs to be maintained – conditions that are impossible to achieve early in the year without a heated propagator.

Eventually I decided to ignore the instructions and made a sowing in August using a yoghurt pot with a clear lid that enabled light to enter. The result was excellent and from the second week onwards seedlings started to appear. Eventually each was transplanted into individual pots and then placed in a cold frame to over-winter (a sheltered spot in the garden will also suffice). Planted directly outdoors in the spring they rapidly grew and flowered throughout the summer. A slightly challenging plant but well worth the effort.

Not so long ago it was only possible to obtain a timber stain in brown and for that reason sheds, arbours, fencing panels, tables and chairs were quite mundane. Fortunately coloured stains are now available and can rejuvenate a drab fence, summerhouse or set of garden furniture. Initially a degree of boldness is required and I can remember deliberating whether to stain a newly constructed arbour brown or to choose one of the new pastel shades. I chose the latter in ‘Sea Green’ and have no regrets.

Cuprinol has made that decision easier by introducing sample pots that can be ordered on line and delivered within a day or two (www.cuprinol.co.uk). All the testers come in specially designed packs which conveniently fit through the letter box. Each contains a little pot of stain and a brush and with 23 different colours to try you may long for the day when the only colour was brown!

If you have any gardening questions for Danny contact him by e-mail on This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Weeding Out Your Garden Problems

We have a Buddleia that has become quite woody and overgrown. The butterflies really enjoy this tree and we don’t want to lose it so can you advise the best way to  prune it?

The recommended method of pruning Buddleias is to cut all the shoots to a very low level early each year. However this sound advice is only appropriate when the treatment has been carried out from when the plant was young. With older, unpruned plants I would not recommend being so severe and would initially suggest cutting the shoots back to perhaps six feet. In the following year, providing new shoots are developing, cut a little lower. The pruning appears harsh but it is important to keep the plant youthful otherwise it becomes woodier, as you have experienced, and will produce far fewer flowers.

Couch grass has invaded my lawn. It was only sown a couple of years ago using a ‘luxury’ grass mixture but it has now been ruined. Can you recommend a treatment to eradicate it?

Couch grass is one of our native perennial grasses and wouldn’t be a problem if it only appeared in a utility lawn. Unfortunately there is no specific chemical treatment for any weed killer would also kill the finer grasses. Where the clumps of couch grass are in small numbers I would carefully uproot them, add a little soil to the area and sprinkle seed over the surface. If the couch grass is very invasive you can spray each site with a weed killer, allow it to work and then over-sow with your chosen grass seed. Seeds of couch grass will reappear of course and only by being vigilant will you have the perfect lawn you desire.

Cuttings

•    To propagate clematis plants, peg shoots down to the soil to root
•    Continue to take cuttings of fuchsias, impatiens and pelargoniums
•    Check that all flowering dahlias and chrysanthemums are firmly tied to their supports
•    Deadhead bedding plants, pansies and violas
•    Brush away soil from around onions to help with ripening
•    Prune rambling roses following flowering