Facebook Questions and Answers for the 8th June 2012

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

Karen Stewart

My petunia plugs had to stay in greenhouse longer than I would have liked due to bad weather. Now in flower bags/ground. Loads of leaves but no flowers! Did I feed them wrongly & is there still a chance they will flower? Thanks

Hi Karen, your petunias could just be a bit slow to get started or alternatively it could be the type of fertiliser you are using. Some general purpose fertilisers have a slightly higher nitrogen content relative to the other nutrients. If the soil is rich in nitrates the plants will concentrate energy into growing leaves rather than flowers. Make sure you use a fertiliser high in potassium (such as tomato food) to encourage lots of flowers. Your petunias sound nice and healthy so I am sure they will flower when they're ready! I hope this helps.

Peter Sharp

Other than slugs & snails what else could be eating my hostas. They are in pots with a covering of gravel over the compost to stop the slugs and snails & I regularly check the pots as well.

Hello Peter. Slugs and snails are usually the main culprits, but vine weevils are also particularly partial to hostas, especially pot grown plants. The first sign of damage is often small notch shaped holes in the edges of the leaves caused by the adult weevils. Despite being a common garden pest, the adults are quite reclusive and are often difficult to spot in the garden. Whilst the damage can look very unsightly it is rarely sufficient to have a terminal effect on the plant. Of course, if you do see them, then they should be squashed immediately! However this damage is a good indicator that you should start to treat your plant to protect it from damage caused by the vine weevil grubs that live beneath the soil surface. The grubs feed on the roots of the plant which can be fatal. The best way to control these grubs is to use nematodes, which are a biological control that can be watered onto the compost. Nematodes will kill the grubs and break the life cycle, allowing you to get the vine weevil population back under control.

You can also repot your plants in spring to help clear away any grubs and eggs that have overwintered in the soil. Make sure that you shake all of the compost away from the roots and pot them into brand new, fresh compost. Don't add the old compost to your garden or the compost heap - it should be bagged up and taken to your local tip. I hope this helps Peter. Best of luck.

John Goss

How can I control leaf miner on my Gerbera plants?

Hi John. Gerberas are often affected by Chrysanthemum Leaf Miners. The easiest option is to simply pick off the infected leaves and burn them. If there is only very slight damage then you may even get away with simply squashing the maggots at the end of the tunnels in the leaves without actually removing the foliage itself. However in more severe infestations then you may need to spray with a suitable insecticide. A systemic insecticide is best as this will be absorbed right into the plants tissues where the larvae are. Also try to keep your plants healthy and well fed in order that they can outgrow the damage. Best of luck.

Nicola Price

My Dahlias are growing but seem to be all leaves, no flowers as yet, is there something I need to do? Also one of my Dahlias has lots of holes in the leaves (due to slugs I presume) does this mean it will die?

Hi Nicola. Your Dahlia may look a little unsightly from being eaten but this shouldn't kill it. Slugs and snails love Dahlias so you might want to consider sprinkling a few slug pellets about the base of the plants to prevent further damage.

It sounds as though they are growing well though. Don't worry that they have not produced flowers yet; it's been a very cold start to the summer and many plants have been delayed. Your plants should start to produce flowers soon, particularly if the weather warms up a little. You might want to try feeding them with a high potash fertiliser such as tomato feed as this will help to promote flower production. Avoid fertilisers with a higher nitrogen content as this can encourage lots of foliage at the expense of flowers. I hope you get some flowers soon.