Ask Adam: part three

Your questions answered

We recently invited you to submit your gardening questions for Adam Pasco, editor of Gardeners' World Magazine. View Adam's third set of answers, below.

Every two weeks between now and Gardeners' World Live, 13-17 June 2012, Adam Pasco will be answering a selection of your gardening questions.

If you'd prefer to ask Adam a question in person, you can do so at the Gardeners' World Theatre at Gardeners' World Live, where he'll be appearing regularly. Save 10% on your show tickets by booking now:

Tel: 0844 581 1344
Book online quote code GWNE




I have two old trees covered in a dark green ivy. My neighbour told me to remove the ivy or it would kill the tree (choke it). Is this true? From Bichon26

Adam says: I agree with your neighbour. Our native ivy, Hedera helix, is a rampant climber, and can cause problems to trees, particularly if they are old or not growing strongly. While some might argue that ivy can grow on healthy trees without causing a problem, I would never recommend growing ivy on a tree in your garden.

Although ivy is unlikely to completely smother all the branches on a tree it will do a good job trying. Ivy is an evergreen climber, and a large head of ivy acts rather like a sail by catching the wind. During strong storms it's often ivy-clad trees that topple, as while bare branches can bend or even break, when ivy catches the wind the force can pull the tree down.

Cut through ivy stems at their base, and remove all the ivy you can. And if anyone has ivy about to clamber up walls or buildings I'd recommend removing this too.

I can't seem to control my neighbour's cat from using my raised veg beds as their loo. Please help! From lucinda.anne

Adam says: Yes, cats cause problems in gardens in more ways than one, killing birds and leaving their mess everywhere. Unfortunately most cats appear to avoid making a mess in their own gardens, but move into neighbouring gardens instead!

I've had this problem on several occasions in the past, and have found that liberally scattering strong smelling cat deterrents in places that cats frequent does keep them away. I've successfully used products containing garlic as well as those with citrus oil.

A gardening friend of mine recommends using any strong-smelling floral soaps, and grating these blocks around his plot. Others have used chilli or pepper powder in the same way. However, applications must be repeated after rain has washed them away.

I have just boxed-off an area of my back garden to grow some vegetables. I am unsure what sort of topsoil/compost I should put into the boxes. Could you please advise me. From steff43

Adam says: Vegetables enjoy a rich and water-retentive but free-draining fertile soil. I would always prefer buying good quality loamy topsoil to fill raised beds, and then digging in extra ingredients if needed.

Check for local suppliers, and try to see a sample before buying it. Avoid buying any that appears very stony or contains weeds. Feel the quality in your hands to gauge its composition, and moisten a handful to see how much clay, loam, sand, grit or organic matter it contains. You could also use a simple soil test kit to check its pH (acidity/alkalinity), as the ideal soil should have a neutral pH of around pH6.5.

You can always add extra grit to improve drainage, or extra home-made compost to increase water holding capacity. If you only need a small quantity then buy bags of John Innes No.3 loam-based compost to fill the beds.

What should I do with one of my compost bins that is full of woodlice? Can I just carry on topping up with kitchen peelings, grass cuttings, weeds(?), leaves and newspaper? Will they affect my plants when used later, or discard the whole lot to be safe? From J.Davey

Adam says: Don't worry about finding woodlice in your compost bin or around your garden. These little creatures rarely do any damage to healthy plants, but feed on dead and decaying plant material. You'll find them wherever you have rotting vegetation, as woodlice play an important part in the natural cycle of turning dead plants into compost.

Mixing your compost may deter them a little, and you should be doing this anyway. Every few months it pays to empty your compost bin, mix up the material and refill, leaving it a little longer for everything to fully break down before using around your garden.

While the composting process is completing in one bin you should start filling a second one with the material you describe. It's far better to do this than continually adding fresh material to the top of one bin, and hope to dig out perfect compost from that little door in the base.

We've set our hearts on a couple of trees we'd like to plant to remember my wife's Mum and Dad, who passed away within weeks of one another. They are the Persian Sil Tree (Albizia julibrissin 'Summer Chocolate') and Princess Tree (Paulownia tomentosa). Both are unusual, attractive, but can grow to about 5 metres. Could we keep them shorter that this, or should we try for ones grown on a dwarf stock? From kia-cat

Adam says: What a lovely idea, but you have chosen two trees that can reach a fair size. If you only have space for small trees then I'd certainly recommend you reconsider to see whether alternative small trees would be better. These could include varieties of maple, crab apple, Amelanchier lamarckii, cornus, or flowering shrubs like one of the many ornamental viburnums, but there are many others.

It's a matter of 'right plant, right place', and I always prefer letting trees achieve their own natural size and shape with the minimum interference at all. Pruned trees look like 'pruned trees', and lose some of their natural beauty.

With that said, it is possible to prune Paulownia hard down every year to keep it to a manageable size. This type of pruning is often called coppicing or pollarding, and involves cutting all stems down to a woody base in late winter, before growth begins. With Paulownia this hard pruning encourages strong new shoots to develop from the woody base that carry large leaves, but you won't get any flowers.

I hard prune several shrubs in my garden in the same way each year, including buddleia, dogwood and sambucus. Albizia can also be pruned, but not as severely as Paulownia.

Last year I bought 1000 double early tulips and planted them in November. I was very excited about them coming up, but sadly about 30% of them are budding near ground level. Will they shoot up? What's wrong with them? From viji

Adam says: There could be a number of reasons for this to happen. Firstly, I wonder whether all your tulips were the same variety, or was this a mixture of different ones. If so, different varieties could have responded differently. I'm not sure where you live, or what soil you have, but November can be quite late in the year to plant tulips in very cold districts. Wet soils and cold weather can be detrimental to bulb development, and many of us experienced quite cold conditions last winter. This can influence flower production and development. And what about planting depth? Tulip bulbs can be planted fairly deeply, particularly if bulbs are being left to establish. I'd recommend planting bulbs of most large tulip varieties at least 15cm deep, and even down to 20cm if you can manage. Deeper planting should also reduce the influence of winter frost and cold on flower development.

In summary, if correctly planted then I think the poor development is probably physiological. Provided their leaves appear green and healthy then I don't think disease is to blame. While they won't recover this spring I would give the bulbs a generous liquid feed, allowing them to complete their growing cycle and die down naturally. Next spring I'm sure they'll flower beautifully. Do let me know.

Ask Adam: part one

Ask Adam: part two

Ask Adam: part four

Ask Adam: part five

Ask Adam: part six