Ask the Expert

What can i do to get rid of black deposits all over the leaves of a large camelia. It's almost completely covered in it. Thank you

Posted 11/06/2012 by Tomas, Waterford

Hello Tomas
It sounds like you had a problem with aphids. The result of an aphid infection is the sooty deposits you describe. They excrete excess sugar after sucking into the leaves. This sugary substance causes the mould to grow on it.
Check the plant for any sign of aphids but they may be all gone now. Try washing the leaves with a luke warm soapy mixture.
If the camellia is growing underneath a tree the deposits may have fallen down from the tree above.
When camellias have finished flowering it is a good time to give them a liquid feed to strengthen up for next year. You may need to spray with an insecticide to prevent this in the future.
Brendan Howell

I have some cypress shrubs that need pruning but im not sure how much to take off hem and when to actually cut them. Also if I want to move them when is the best time to do that too? Thanks

Posted 11/06/2012 by Jackie, Dublin

Hello Jackie
You should always cut conifers or cypress when they are actively growing. Cut back the current seasons growth by about 2 thirds. This should be done each year and not to leave it go for several years as you will end up with woody unsightly material.
So you may cut it now!
Regarding moving them this should only be looked at in the autumn. Choose a time when ground conditions are not too wet or cold. You will need to dig well around the plant so as you dig out a large root ball with each one. Replant into a bigger hole with plenty of fresh compost to encourage new root development.
Brendan Howell

Can you please recommend ways to keep my shrubbery and flower borders weed free as I have just finished weeding them. It is a large area. Love your website as it is full of great advise!

Posted 11/06/2012 by Michael, Kildare

Hello Michael
Thanks for the nice comments on the web site!
Now that you have put the effort into weeding this large area you can do several things.
Get a good sharp hoe and as the new weed seedlings germinate run over them with the hoe. If you do this on a bright windy day they will disappear in no time. You are preventing new weeds from flowering and setting new seed so you break the cycle over time.
Another good way is to spread a layer of bark mulch over the area. A 2-3 inch layer will prevent new weed growth and also protect the soil from erosion and drying out. On large areas use the Growise Landscape Mini Chip and on smaller areas use Growise Superfine Bark.
Brendan Howell

I have a very very large phormium; nice specimen but a good few leaves looking a bit tatty from wind damage etc. can it be pruned to tidy it up and how hard can it be pruned? Also have a cordyline with lots of dead leaves, I always believed they should be left to fall naturally but I'm tempted to pull them off!!? What advice please?

Posted 11/06/2012 by Rita, Cork

Hello Rita
Regarding the phormium you will always have a certain amount of dead leaves. These should be removed regularly and this will help to promote young growth. If the plant is gone quite large for the area it is in you could lift it carefully in the autumn and pide the plant into several young plants. At this stage you can cut back the foliage hard. Take care when replanting as phormiums do not like to be planted too deeply.
With the cordyline as the lower leaves die off pull them off. This also encourages new growth and keeps the plant tidier looking.
Brendan Howell


I have a rambling rose which is covered in a type of white  
milldew and it has lost some of it's leaves. It was really healthy and green  
and has lots of buds, but now looks really miserable. Is there anything I can  
do to make it healthy again? Thank you.

Posted 05/06/2012 by Josephine, Co Cavan

Hello Josephine

This type of mildew is a fungal disease and it will defoliate a rose in no time. Warm days and cool nights kick it off. The fungus will draw the moisture and nutrients out of the leaves with the result that they will fall off.
Remove all leaves under the rose and dispose of them otherwise it will splash back up onto the plant.
There will be many chemical controls available in your local garden centre. Some natural tips would be to make sure there is good air circulation around the plant. Water well during warm weather and mulch around the base of the plant. Roses like plenty of feeding so use a good rose food starting each year in March so you have a strong healthy plant to fight off disease.

Brendan Howell

I have nandina domestica plant - which compost should it be in? Leaves curling and turning brown, what could the problem be?
Thanking you

Posted 28/05/2012 by Anne Marie, Waterford

Hello Anne Marie

Nandina domestica "the heavenly bamboo"is a beautiful plant. It requires an acid to neutral soil so it would be best to grow it in Growise Ericaceous compost. If it is in a container it may be hungry or is just suffering from the recent cool wet weather. It does not like waterlogged soil so look at drainage around the plant if it is in the open ground.
Try re-potting the plant into fresh compost and put it in a sheltered position with plenty of light. This will bring fantastic colour in the autumn if you care for it now.

Best of luck,

Brendan Howell

My rhubarb this year is very poor (weak stalks and thin).  Is there anything I can do to help it along?

Posted 28/05/2012 by Dympna, Co Clare

Hi Dympna,

A couple of things. If your rhubarb is in the ground for a number of years the centre of the plants begins to rot and this will weaken the shoots. In the Autumn dig it up and cut away the dead parts and pide up the new stools which have developed. Replant them with loads of farmyard manure and compost as rhubarb loves a rich soil in organic matter.
If the plants are new they will take a season to establish so you are better not to harvest any of the stems and leave them die back into the plant which will strengthen it for next year.

Best of luck,

Brendan Howell

What drought resistant plants/flowers would you recommend for a hanging basket? I will be going on holidays so watering will be a problem.

Posted 10/05/2012 by Joe, Limerick

Hello Joe

Going on holidays will be a problem no matter what you put in your basket. The best thing to do is take it down and stand it in a sheltered, semi-shaded area. Put a container underneath and fill this with water before you go. Otherwise try and get a neighbour to come in and water it for you. The compost you use is important also, use Growise Tub & Basket which contains a swell gel that the roots can get moisture out of even when the compost becomes dry.
The following plants will tolerate dry conditions longer in a basket-Brachycome, Bacopa, Nasturtium, and Ivy leaf Geraniums.

Have a good holiday,
Brendan Howell

I have a rhodedendron plant which is about to bloom but in the last few days the leaves have gone brown. Why is that and will the plant survive?

Posted 10/05/2012 by Mary, via Facebook

Hi Mary,

If the rhododendron  is newly planted it may have dried out earlier in the year. This would be showing up now in the older leaves as browning around the edges. Also they do not like to be planted deeply. Check the soil is not up around the base of the plant and if needed pull some soil away from the base of the plant. Rhododendrons are surface rooting plants which like soil with good drainage but also with good water retention properties. Is it water logging in the latest wet conditions? Have you fed it this year? Fertiliser should be well spread out in the rooting area and not close up around the base of the plant as this will cause a burn effect on the leaves. 

The plant will survive if it is putting on new growth and all the leaves do not turn brown.

Good luck, 

Brendan Howell

How do I stop sunflower seedlings from becoming too leggy too quickly?

Posted 10/05/2012 by C Casey, Dublin


Firstly make sure the seed you sow is a hybrid seed so that the plant will be true to the parent material.

Do not over water the seedlings and sow them as thinly as possible. They will also need plenty of direct overhead light ideally in a glasshouse. Otherwise if on a window sill keep turning them to the light every day.

After planting out keep the area around the plants as clean as possible and you should plant them where they are in full sun. This will keep them stocky and not competing for the light and nutrients in the soil

Brendan Howell

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