Facebook Questions and Answers for the 11th May 2012

Hello Facebook fans, thanks for your questions this week, here are Carly's replies:

Andrew Gillard

Got a question for Carly :) I'm growing some cucumber plants from seed, which went great until I moved them outside. I tried acclimatising them to the outside first by moving them onto the balcony for a few hours a day, but they would always wilt immediately. I ended up just moving them straight into the greenhouse, into a grow-bag, but that was a couple of weeks ago and they're now looking more ill than ever - completely wilted, shrinking down from their original height, and with a couple of leaves looking a bit pale/yellow and one with a brown patch.

They're definitely not *under*-watered. They might be over-watered because I forgot to cut drainage holes in the growbag at first, but I rectified that almost a week ago and they haven't improved (if anything, they've got worse). The temperature hasn't dropped below 5°C since I put them out there, and I don't think it's got too hot, either (hooray British weather...), so I'm utterly stumped. Would you be able to shed any light on this matter, please? Thanks

Hi Andrew, unfortunately it is still much too cold for cucumbers to go outside (or into an unheated greenhouse). The weather has been less than ideal for tropical crops so far this year! Cucumbers need an ideal temperature of 18-30°C and are often damaged at temperatures below 10°C. Greenhouse types (all female) are more sensitive than outdoor types but both need good warmth to succeed. Sudden changes in temperature can cause yellowing leaves and brown/crispy patches to develop around the edges. Waterlogging can also cause yellowing leaves and wilting. It may be a combination of the two which has caused your cucumber plants to look so poorly.

You may be able to save your plants if you can bring them back inside to a warm and bright place. Don't water them until the top few inches of compost feels dry. If this would be too difficult then you just about have time to sow some more seed for this year! When the weather warms up they will soon catch up. I hope this helps Andrew, best of luck.

Helen Finch

Question! I have three Acers in my garden in Salford, one Acer palmatum Atropurpeum, one Orange Dream, and one other purple-leaved maple. All of them put out new leaves in spring, but the two purple-leaved maples have suddenly lost all of their leaves, while the Orange Dream is flourishing.

The Orange Dream is in a pot with ericaceous compost, and so is the acer palmatum Atropurpeum. The other purple-leaved maple was planted in the ground last August. I don't understand why the purple-leaved ones are so unhappy, but the green/orange-leaved one is fine. They are all three within a metre of each other, on the shady side of a damp garden. What could have happened? And is there any chance of my purple-leaved maples recovering?

Hi Helen, sudden leaf loss is caused when plants are stressed. I would look to the roots of the plants and make sure they are not too dry or too wet. Waterlogged soil will drown your plants, causing roots to die back. The leaves will then lose more water than they can take up so they die back to conserve moisture. It's also worth checking the root system of your potted Acer and looking out for ant's nests or vine weevil larvae (white grubs with brown heads) which could be chewing the roots. If you do identify insect damage, bear in mind that they could have been in the pot of the Acer which is now planted in the ground. Both ants and vine weevils can be treated with nematodes or chemical drenches watered into the soil.

Drying winds or frosts can also cause leaves to scorch and shrivel - newly emerging leaves are the most sensitive to this. It is well known that cultivars with heavily dissected foliage are more prone to environmental stresses than others - it may be that your purple varieties of Acer are more sensitive. If you can identify the problem and rectify it then your Acers should make a recovery. I hope this helps Helen - let us know how you get on!

Chas Howard

How do you take cuttings from Pelargoniums?

Hi Chas, Pelargoniums are good at rooting from cuttings so you should have success with this technique. Choose vigorous healthy shoots to take your cuttings from. Cut off shoot tips about 10cm long from the parent plant, cutting just above a bud or leaf joint to keep the parent plant tidy. Take your cutting and cut just below a leaf joint (this is where all the hormones are concentrated for new growth), aiming to make the cutting about 5-10cm long. Remove all the lower leaves so that you are left with just two or three - too many leaves will cause your cutting to wilt and die.

Fill a small three inch pot with a mixture of fifty percent multipurpose compost and fifty percent perlite (available at all good garden centres) for good drainage. Use a dibber to make holes in the compost around the edge of your pot and insert the cuttings into the holes. Pelargonium cuttings don't need to be dipped in rooting hormones. Water the pot sparingly from above with a fine rose watering can and put your pot into a clear polythene bag to increase humidity around the plant material. Keep them somewhere warm and bright for six to ten weeks until they start to grow and you notice roots appearing at the bottom of the pot. They are then ready for potting on! I hope this helps, good luck.

Ann Longford Was Dutfield

I have an Acer and noticed a white speckle substance on the lower stem and branches?

Hi Ann, this sounds like it could be scale insects. Some species lay their eggs under white waxy fibres in early summer which appear as white spots. The adults will appear as scales or shell-like bumps on the stems and undersides of the leaves. If you can identify this as scale insects then it would be best to treat the problem with a chemical pesticide. These pests suck the sap from the plant and can weaken it over time. The adults are difficult to treat because of their hard protective shell so concentrate on killing the young nymphs to bring the problem under control. The nymphs hatch in June and July so this is the best time to spray. There are lots of insecticides which can treat this problem which are available in all good garden centres. Any containing the active ingredients 'deltamethrin', 'thiacloprid' or 'acetamiprid' will be effective. The scales will remain attached to the plant once they're dead so it's only when new growth appears that you'll be able to see whether the treatment has worked. I hope this helps, let us know how you get on!

Chris Dorsett

Is there a plant food that is fit for almost everything?

Hi Chris, you can't go far wrong with a good balanced fertiliser for most garden plants. These are available at all good garden centres and are normally labelled 'growmore' or 'general purpose'. If you're growing fruit crops e.g. strawberries, tomatoes, peppers, courgettes etc, you'd be best to use a balanced fertiliser in the spring and then a fertiliser rich in potassium, such as tomato food, in the summer. If you're growing leafy crops such as leeks and cabbages then you'd be best to use a fertiliser rich in nitrogen - chicken manure pellets are good for this, although growmore would work just as well.

One of the best ways to improve plant growth overall is to add organic matter to your soil each year, either dug in or placed as a mulch around plants. Not only does this slowly release nutrients, it encourages worms and beneficial fungi and helps build the soil structure, leading to a better growth environment. I hope this helps!

Another question for you. I have Ivy growing up a fence and on a shed. I planted it so it's meant to be there, but will it cause a problem?

Ivy doesn't normally cause a problem on sound surfaces - the aerial roots are harmless. The only time it can become damaging is when it finds its way into weak points such as crevices or cracks. Ivy is strong and this can cause structural damage. Keep an eye on its growth and remove any problematic shoots or roots as they become apparent.

Emma Gardner

Hi, I have a fence that doesn't get any sun are there any plants that will grow up it, thanks

Hi Emma, shady areas can be quite challenging but there are a number of climbers that originate from woodland areas that will be happy growing in part shade or fully shady conditions. You could try Lonicera japonica 'Halliana' which is an evergreen honeysuckle - they are vigorous climbers and the flowers smell fantastic throughout the summer months. You could also try Akebia quinata which is again very vigorous, with lovely bright green foliage (semi-evergreen) and fragrant purple flowers in the spring. Parthenocissus henryana (Virginia Creeper) is a vigorous, deciduous climber and has the most amazing red foliage in the autumn before the leaves fall. Another good deciduous climber is Hydrangea petiolaris (Climbing Hydrangea) which has an abundance of summer flowers and reasonable autumn colours too. Clematis are a good choice for a shady position as they flower profusely - try Clematis alpina, Clematis armandii (which is fragrant) or Clematis montana. All are spring flowering and very vigorous - they should quickly cover your fence within a few years. Some varieties of rambling rose are very shade tolerant, such as 'Alberic Barbier', 'Gloire de Dijon' and 'Madame Alfred Carriere'.

If you were interested in free-standing shrubs which can be trained as wall shrubs you could try Berberis, which is evergreen and spectacular for spring colour and autumn berries. Another shade-tolerant wall shrub renowned for its autumn berries is Pyracantha. Also good is the Japanese Quince (Chaenomeles speciosa or Chaenomeles x superba) which has pretty spring flowers followed by edible fruits. You could try Cotoneaster horizontalis, Euonymus fortune, Garrya (Silk-tassel bush) or Leycesteria. All are fast-growing and will cope well in shady conditions. I hope this gives you a few ideas to start with!