Recklessgardener clinic - with Martin Fish, expert horticulturalist

Qu - "My well established firethorn has, this autumn, developed leaf miner - the "mines" are one per leaf, centred on the midrib and sometimes mining at least 50% of each leaf. The leaves themselves are now turning dark reddish - there are just a few new shoots of normal dark green. There is a horse chestnut tree about 20 yards away. HELP please! Is it normal for pyracantha to suffer leaf miners? Is there any cure? Can I spray it - and if so, when should I start?

PS Please don's suggest that I cut away the affected parts - there won't be anything left! It grows up the front wall of the house and provides our only greenery." from D.M.

Martin says ....

Pyracantha is often attacked by leaf miner and where the infestation is heavy the plant will look a mess. Fortunately it is possible to control in the future, but there is nothing you can do to undo the damage already caused to the leaves.

I know you don't want me to suggest cutting out affected branches, but by trimming the growth back a little not only will it get rid of some of the damage, it will encourage stronger new growth in spring. However, pruning now will affect flowering in late spring, so don't go mad.

As for controlling further attacks; when the plants is making new growth in spring you can spray with a systemic insecticide such as Provado Ultimate Bug Killer. This will give control of all leaf-eating and leaf-sucking pests for several weeks at a time. For total control you will need to repeat the spray a couple of times through the summer months. This spray will also control scale insects and woolly aphids which are also serious pests of pyracantha.

Qu - "I bought my friend an orchid at Christmas 2006, and since then it has done nothing but flower, no root growth, no new roots, just keeps on flowering. The leaves are dark green and it seems happy - just won't go to sleep - It gets fed only in the summer once a fortnight with orchid feed - is so much flowering normal?" from P.Dyson, Formby

I suspect the orchid is a phalaenopsis orchid which is also known as a moth orchid. They have lovely flowers in a wide range of colours. The modern hybrids do have a long flowering period, although your plant seems to be flowering for longer than normal. It is obviously very happy and all I would say is feed all through the year rather than just in summer because in centrally heated houses they continue to grow through the winter months.

Remove flowers as they fade but do not cut back the flowering stem too much as this type of orchid produces side shoots from the main stem that carry even more flower buds.

Qu - "I bought a euonymus emerald gaiety recently to plant in my rockery as on the label it noted maximum height 40 cm. It wasn't until I got home that I remembered reading about it a while back and thought I'd read they grow bigger? I was right when I checked on the internet and some books I had they all said it grew 3ft to about 5ft high. Also a relative of mine said she'd bought some shrubs that have grown bigger than their stated size.

The other day I was in B & Q and one euonymus emerald gaiety I saw said on label maximum height 45cm. Yet another euonymus emerald gaiety plant - a slightly bigger specimen - stated a hight of 3ft. could I have I bought a dwarf version?" from M.F.

Plant labels can be very misleading when it come to the height and spread of plants as some quote the size after say 5 or 10 years and other will suggest the ultimate size. I find that the RHS Encyclopaedia is the most reliable, but even then it is only a guide. Growing conditions, average temperature and soil type all effect the growth of plants. For example, in my garden I also have Euonymus 'Emerald Gaiety' that are approximately 15 years old.

Where it is exposed the plants are approximately 60-75cm tall, but in asheltered corner of the garden where the plant is against a sunny wall it has grown to around 1.5m up against the wall.

Qu - "Could you recomend some suitable plants for growing in the gaps between paving slabs?

I would like something that isn't to vigourous and can withstand being walked on. Preferably something that is long flowering with tiny dainty flowers." M.F.

A few low growing alpines that are ideal for growing between cracks in paving are Raoulia australis, which has silvery foliage and yellow flowers, Silene acaulis which has small green leaves and pink flowers and Prattia pedunculata which has small star-shaped blue flowers. Many of the low growing thymes, sedums and saxifragas would also grow well in this situation. A visit to an alpine nursery would be the ideal place to buy this type of plant.

Can you help? Please see the attached photographs. One of these conifers has died.

They have been in the garden for 7/8 years. What is it and where can it be bought? Regards Agnes B.

The conifer that has died in your garden is a type of Cryptomeria japonica which is also known as the Japanese cedar. From the photograph it is difficult to say exactly which cultivar it is, but I think it may be one called 'Sekkan-sugi'. These conifers are readily available in many garden centres and nurseries and what I suggest you do is take a piece from the surviving plant in order that you can make sure that the new plant is the same type.

Qu - "I've recently purchased a small laurus nobilis. How would I train it into a standard tree (lolipop style) and permanently kill off the lower branches to leave a bare trunk." M.F.

To train your bay (Laurus nobilis) into a standard tie the main, lead stem to a cane which will keep it straight and growing upwards. As the plant grows the lower side shoots growing from the main stem can be removed with secateurs making a clean cut flush to the main stem. When the main stem is still young it will try and produce more side shoots and these should be removed on a regular basis to maintain a clear stem. Eventually as the stem turns woody, the bay will concentrate its effort on making growth at the top of the plant.

When the bay is at the height that you want, pinch out the growing tip and allow several side shoots to develop. These side shoots need stopping when about 15cm long to encourage them to bush out. It's then a case of pinching out and trimming the head to get a round shape.

If you have a gardening problem then email sandy@recklessgardener.co.uk and your question will be passed to Martin. Questions and answers may appear in Reckless Gardener Magazine.