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Climbers, climbing plants & wall shrubs

Help solve your gardening problem. Here are the answers to some commonly asked gardening questions about Christmas trees with hints, tips and advice.

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We've got a really overgrown clematis and we're not sure how hard we can cut it back to get it back under control.

This is typical of a clematis that has been left to its own devices for a few years. You could just cut back and tidy up the 'mop of hair' on the top - but to be honest it's never going to look great and tidy. Although you could try training in some of the regrowth so that it hides and covers the bare stems lower down.

If it was mine I would be more brutal and take it down to around 30cm (1ft) or so in height. However, it is a bit of a risk as clematis can be a bit tricky if cut back so brutal. But I'd be willing to take the risk and if it died replace it.

After pruning make sure you give a good feed with a granular rose fertiliser and water it in well.

Some of the stems on my clematis have turned limp and started to wilt. What has caused this?

If the stems don't collapse suddenly, and the leaves don't turn black then this ISN'T clematis wilt.

My inclination is that it is physical damage to the stems, which are very brittle; once they are damaged they cannot move water to the top of the plant which then wilts. Dry and waterlogged soils would produce the same effects, as would snails or similar chewing through the stems.

I always use plastic clematis netting to support my clematis - because there are lots of places for the tendrils to attach themselves the stems are always much better supported and are less likely to be damaged.

Providing there is good growth lower down on the plant, I would cut back badly affected stems to this point. Even where no growth is apparent, hard pruning can stimulate new growth from ground level. Give the plants a good feed with a granular rose fertiliser, water in and keep the plants well watered during dry periods, giving around 10-litres (2 gallons) per week during growing periods.

I haven't been able to find information about the best way to transplant my clematis. I need to move it because it is growing on a trellis that needs to be removed for construction on our house.

Clematis are best moved when dormant - that is when they have dropped all their leaves in alte autumn and winter. It can be done at any time during the dormant period providing the soil isn't frozen solid or soaking wet - waterlogged.

It is best to hard prune before moving - say to about 45cm (18in) from the ground - just above a pair of buds - making sure there are still a few buds further below the cut.

Before moving, give the soil around the roots a good soaking (preferably the day before), and dig up as big a rootball as possible. Replant in a good-sized planting hole in well-prepared soil. Plant slightly deeper than it was originally growing. Then give a good watering to settle the roots and water regularly throughout the first spring and summer.

The other option is to just prune and carefully bundle the stems away from the wall and retie them to the trellis once the reconstruction work is complete - that is providing the plant won't get damaged by the reconstruction.

We are having trouble with a clear slime starting at the base of our clematis and traveling about 60-90cm (2-3ft) up the stems. What is it?

This sounds like bacterial slime flux. This disease used to be unusual, but it is becoming more common especially on montana clematis.

Unfortunately, being a bacterial disease there are no cures. Spraying the plant and watering the soil with a copper fungicide may help, but can't be guaranteed.

All you can do is dig up the plant and destroy it. Don't replant a clematis in the same place.

What is the easiest way to propagate clematis?

The best way to propagate all clematis - even the species - is through layering.

Choose a supple stem or two that can be pulled down to the ground. Make a shallow slanting cut through the bark on the underside where it touches the ground, wedge the cut open with a match or similar and apply hormone rooting powder to the cut.

Peg the shoot into a small pot of compost which has been sunk into the ground and weigh down the stem with a pebble or small stone.

It may take six months to root but it is the most successful method.

If you want to have a go at taking cuttings, the best time is in July using sem-ripe cuttings.

Why are the lower leaves of my clematis turning brown? It looks like they are covered with a fungal disease.

It sounds like your clematis is suffering from clematis mildew, which is always worse when the plant is under stress and particularly in warm, dry conditions which causes stress at the roots.

Clematis mildew is always worse when the soil is dry - often a problem when growing clematis up a brick wall. Soil can dry out quickly and clematis need around 9-litres (2 gallons) of water per week when growing for strong growth. Aim to keep the soil moist (mulching the soil will also help), but keep the water off the foliage.

Spraying the plant, support and surrounding soil with a good garden fungicide should help keep it clematis mildew check. You can protect the plants from future attacks and partially clear up what's already there by spraying with Bayer Garden Fungus Fighter or Scotts FungusClear Ultra.

New plants sometimes struggle to get their roots established and are often prone to clematis mildew.

I'm confused by clematis pruning. Can you make it easy for me?

Yes. Just read my page on clematis pruning!

What is the best way of supporting clematis?

Clematis need plenty of really good and strong supports in order to grow well. If they are allowed to move around too much in the wind the stems can twist and shatter.

Lengths of fishing line or even wires won't be enough. So your best bet is to use rigid plastic mesh netting - this is usually sold as clematis netting - or wooden trellis.

What is the best way of removing the roots of an ivy from a brick wall?

Ivy roots can be difficult to remove from a wall, especially if the bricks and mortar are old and crumbling.

Start by removing as much by hand using a trowel or a scraper. More stubborn roots can be scraped off using a wire brush, or carefully burnt off with a blow torch.

How do I look after a passion flower?

The common blue passion flower (Passiflora caerulea) is quite hardy and can be grown outside in Britain but will need a sunny, south-facing aspect and a good, well-drained soil.

Make sure you give it some strong support to climb up, such as a trellis. Train the early stems to cover the support as you like - a fan is most popular.

Keep well watered in summer and feed with a solid high potash feed - such as a rose or tomato fertiliser. Feed on planting and again in June to promote lots of flowers. In subsequent years feed twice a year in April and June.

In winter, protect the base of the plant with a thick mulch of bark, straw or similar.

The shoots may be killed and die down in a severe winter, but the mulch should protect the roots. In spring you should get plenty of young new growth from below ground level.

If the shoots don't die down just prune some of the top growth away (up to one-third) in April.

I have been given a passion flower that is growing round a hoop. I would like to know when to plant this out in the garden and whether to untangle it from the hoop!

The time to move your passion flower outside would be in late spring after the worst of the winter weather is over.

I would certainly untangle the shoots from the hoop, and train them out in a fan shape on some trellis.

My passion flower has formed orange fruits. Are these edible?

The common passion flower, Passiflora caerulea, does produce ornamental fruits in a good summer. Although ornamental, they are not really worth eating as they contain very little flesh, and this is somewhat bitter; some people do use them to make a rather tasteless jelly!

But allowing the fruits to form may reduce flowering next year, so it may pay to remove all or most off them.

The edible passion fruit is a different species - P. edulis - which needs to be grown in a greenhouse or conservatory.

I recently purchased a Solanum rantonnetii plant. However it appears that this is rather tender and I don't have a greenhouse or conservatory. Can I keep it as a house plant? What sort of potting compost should I use?

Solanum rantonnetii has a minimum winter temperature requirement of 7C (45F), so you will need to find a position that gives this amount of warmth.

I would certainly keep the plant in the house until spring - somewhere it will get plenty of good, indirect light, too. It can then go out on the patio for summer as it will certainly do better outdoors than stuck in the house. But, it will need to be brought back indoors in autumn and overwintered frost free.

You can use any good potting compost for it - such as a good multipurpose.

Leave any repotting until late March/April.


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