Facebook Questions and Answers for the 18th July 2014

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

Susan Heath

I accidentally watered my fruit and veg with weed killer - as soon as I realised I drowned them with water. They have survived but will they be edible? Thanks.

Hi Susan, as your plants have survived I would expect most of the weed killer to have been washed away into the soil where it will be harmless. The exception is long-term residual weed killers (often labelled as path or patio weed killer) which last up to 6 months in the soil. If the plants had absorbed any weed killer you would see signs of damage, through distortion or yellowing/browning of the leaves and fruit. If you believe the plants have absorbed a glyphosate-based weed killer (systemic - kills at the root) I would be careful about eating these as the glyphosate can remain in the plant's vascular system. Check the label for the active ingredients. I would advise contacting the company who produced the weed killer before eating any of your crops as they will know best what is included in their formula and can advise you further. I hope this helps Susan.

El Bells

I have been trying without success to get houttuynia, not sure on spelling, out of my borders for about ten years - how do I do it cos now it's going into other plants and into my lawn? Thanks.

Hi El, Houttuynia is an attractive plant in the right place but unfortunately it does like to spread, especially in moist fertile soils. It spreads via underground rhizomes and can grow back from pieces left in the soil, so digging has limited effect. Persistence is the key! Spray plants now with a systemic weed killer containing glyphosate, such as Roundup, which is carried through the plant to the root. If there are lots of ornamental plants nearby, cover them with plastic sheeting whilst you spray the Houttuynia, as glyphosate will kill any plant it comes into contact with. Alternatively use gel weed killers which you dab on the leaves. It is also beneficial to spray the weed killer in the evening as more of it will be absorbed by the plant than during the day. Hopefully you will see some die back after the first treatment. You will likely see some re-growth so keep an eye out and repeat the application as new leaves appear. If you're vigilant, eventually you will exhaust the plant. I hope this helps El, good luck.

Kate Rose

Hi Carly as per previous, I have 2 clematis sieboldii and I was thinking of growing them up an obelisk would this work? Is this variety quite robust do you know, as I do seem to lose clematis with alarming regularity!

Hi Kate, unfortunately Clematis 'Sieboldiana' (as it's now called) isn't the most robust Clematis available. It is a borderline-hardy variety which can struggle to overwinter well, causing slow or weak re-growth the following year. They would however, be excellent for an obelisk as they belong to pruning group 3, so are pruned hard each year. It's best to protect them with horticultural fleece over winter or grow them in a container (1 plant per container) which can be brought under cover away from the worst of the frost and rain. They may remain semi-evergreen if given protection so make sure they have enough light. There are hardier Clematis which would work well grown up an obelisk, such as 'John Howells', 'Comtesse de Bouchard', 'Fujimusume', 'Prince George', and Texensis group Clematis such as 'Princess Diana' and 'Princess Kate'. I hope this helps Kate, best of luck.

Julie Goodwin

Hi VM. I have grown a Cheyenne chilli in the greenhouse this year. It has done brilliantly and is covered in large, green chillies about 4 inches long. I picked one yesterday and bit off a chunk and it had no heat whatsoever. I was gutted. I know they're not fully ripe yet, as they go a lovely orange colour apparently, but I was hoping for a bit of fire. Have I picked too early or is there something I'm not doing right. Many thanks.

Hi Julie, Chilli 'Cheyenne' is regarded as a medium heat chilli and becomes hotter as the fruit matures and starts to change colour. Sometimes, you'll find the first chillies have little or no heat and there can be a lot of variation between the fruits on one plant. However there should normally be some heat at the green stage so perhaps your fruits need just a little longer to mature. Chillies tend to be soft when immature then harden slightly, before changing colour. They sound about the right size so should be nearly ready. The most important thing is to give the plants plenty of warmth and sunlight and keep the compost on the dry side as they resent being wet at the roots. I hope this helps Julie, let us know how you get on.