Thorny problems: getting rid of liverwort and enchanter's nightshade Joy would do well not to use the compost from the invaded bin in the more important bits of her garden, unless she digs it out and riddles (sieves) out every scrap of white root. Thereafter it would be safest to use it as mulch around woodland plants. She could also, if so inclined, take off the cover of the bin (if there is one) and let the weed grow on a little so that it presents a large leaf area and then knobble it with Roundup. Liverwort between paving stones I have a problem with liverwort growing between the paving slabs on my patio. Glyphosate (as in Roundup) seems to have little effect on it. I have tried all sorts of other remedies. Using a flame gun was only temporarily successful and I even tried scraping out the paving crevices, but the liverwort still comes back. Have you any suggestions as to how I can see this menace off? David Earnshaw, via email This hard-to-control, primitive, ground-hugging, algae and moss-related weed of damp and shady places was given an airing on this page a few months ago, when I advised that poor drainage and lack of soil cultivation were largely to blame for its proliferation. Glyphosate is only really effective if a wetting agent such as washing-up liquid is added to it, which helps to prevent it running off the slightly shiny, scale-like "leaves," and of course can only be used where the liverwort is growing away from wanted plants. Shortly after the piece appeared, reader Gillian Sparks, who had been similarly challenged by this weed, sent me a tip she had learnt from a local nurserywoman who, as an experiment, sprinkled sulphate of iron onto liverwort growing on the surface of potted plants. Sulphate of iron on its own should, as Gillian points out, not be used willy-nilly since it is fairly strong stuff, but it should be safe to use, and should do the trick, if applied between the cracks of your paving stones. Time to go? I have three phormiums in my two gardens (one is a holiday home in Dorset). All are very large and have suffered badly in the wind and rain this year. In the past I have removed old leaves with secateurs, but this year things are much worse and I feel drastic action is needed. Should I raze them to the ground with a hedge trimmer? Will they grow back and look smart again? The Dorset plant is in a low-maintenance dry garden, so digging out is not an option. Susan Spearing, Sunningdale (and Dorset) Regular readers will know exactly what I am going to suggest. I, along with countless other gardeners, was once seduced by this thuggish alien that for a few years and mild winters provided an interesting "new look." Their colourful, vertical, sword-like leaves and (in due course), exotic-looking flowers on stiff, lofty stems became a near obligatory Nineties garden feature. I have since come to loathe them as so many have gradually become the most hideous, overbearing blight in so many otherwise comfortably mature gardens. It is interesting to hear that even in Dorset, where you might think phormiums would thrive, yours has become war-torn and threadbare. So, even if you did rather savagely hedge-trim your plants to resuscitate them, I doubt they would ever regain their looks. Yet I urge you to do it. Once they are reduced to ruins, you will see they actually consist of several fan-shaped sections. As you say, the middles of your plants are already dead. It will probably only take a few vigorous sessions with a sharp spade to get them out, lock, stock and barrel - even though you say digging them out is not an option. Bag up the bits and bin them (they won't compost well), and live with the resulting big gaps for the rest of the summer while you think of something with which to replace them. I bet you'll sigh with relief once they are gone, and your gardens will look all the better for their absence. So just do it.