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Garden Diary November 2009
12th November: Cold Sown Seeds 

Many seeds need some cold before they will germinate in spring so its time to think about sowing them now. Also some seeds are best sown fresh so again get ready to sow now. We sow in module trays with a Perspex cover and leave these outside all winter.  Fill the trays with multipurpose compost and tamp down to ensure there are no air pockets. You can use John Innes seed compost but we find this too variable in quality. Water very well and leave to drain.

Seeds we are sowing now include: Angelica, Actaea, Cistus, Eryngium, Francoa, Lysimachia, Penstemon, Primula and Verbena.

Press the seed lightly into the compost. We sow 2 - 3 seeds per module. Cover lightly with sifted compost and label.

Salvia nemorosa Amethyst blooms from June through to November. Easy to propagate by cuttings.15th November: Cuttings

Last month I talked about cuttings from the New World Salvias. This month I've been taking cuttings from hardy types like the nemorosa varieties Caradonna, Amethyst and Lubecca.  I only had very short sections to use and I must say these all seem to have rooted really quickly and easily with the only problem being a little mildew on some of the cuttings from being in the warm humid atmosphere of the propagator. These are already sending up new shoots from below the compost surface which bodes well for forming a reasonable plantlet to go through the winter. Next year I must try and get these done a bit earlier.  

By the way, Salvia nemorosa Amethyst (right) is still flowering well in the garden. 

Persicaria neofilliformis17th November: More Cuttings

Persicarias root rapidly and are good subjects for cuttings if you have some greenhouse or cold frame space left. Varieties of campanulata, microcephala, filiformis, neofiliformis and virginiana all root readily at leaf axils on stem cuttings - microcephala rooting in about 3-4 days!. Unfortunately Red Dragon has plant breeders rights so we can't propagate for sale. Amplexicaulis varieties don't seem to root this way (unless you know otherwise) and need a small piece of rhizome attached. So far I've multiplied single plants of the varieties Blackfield, Firedance and Jo & Guidos Form this way, so next year I can plant out bigger patches (not enough to warrant calling a "drift") of these novel varieties. 

Persicaria neofiliformis has lovely deep green leaves with brown and maroon markings. The flowers (like those of P.virginiana Painter's Palette) are described as "mouse tails" by Alan Bloom. Indeed they do look rather like this in bud but they mature to have tiny (really tiny) red flowers along them creating a most interesting effect at this time of year.

Fuchsia fulgens is a tender perennial18th November: Late Bloomers

Its a very mild autumn and a lot of perennials are still blooming, some expected, some unexpected. The mild weather is allowing some early flowering plants to have another go. Hardy Salvias like Caradonna and Pusztaflamme are all starting to send up new flower shoots - will they make it before the cold weather sets in? Eryngium eburneum is flowering again, mixing ivory flower stems with the brown dead heads we leave on over winter. Helenium Kupfersprudel (Dutch form) is one its third or fourth flush of flower and I need to cut out the old dead stems so we can enjoy these late blooms. 

Some tender perennials like this Fuchsia fulgens hybrid are blooming better than ever they did in the dry summer weather. This one really won't stand any frost so I've taken cuttings (which I potted up today) which will go on a cool bedroom window sill over winter. 

Autumn colour on Acer davidii George Forrest19th November: Hanging on to Autumn

Autumn leaves are lovely and there are few better than Acer davidii George Forrest (right). Golden leaves contrast well with the coral red stems at this time of year. Its blowing a gale today (as it has been all week) and the leaves are clinging on the stems for dear life.  Lets hope the winds subside soon so we can hang on to autumn colour a bit longer. 


21st November: Winter pruning of perennials. Part 1.

At garden talks or through the website we get lots of people asking about winter "pruning" of different perennials. For example today someone visited the website with the question "winter pruning of Veronica gentianoides". Its not something many books cover and I'm not sure much research has been done into this. In this year's September diary I covered "Preparing for Winter Interest" (24th Sept 09) with my views on which plants to leave unpruned. Its a large topic so I'll cover it off in several diary entries over the coming weeks. But for part 1 lets cover Veronica gentianoides and other ground hugging perennials.

Ground huggers: Why would be want to prune these? Well, firstly because they have spread further than we want them and this becomes apparent when we cut back the plants around them. For example I've just noticed that my Persicaria affinis Superba has really spread this year. However now is not a great time for me to cut it back because I want to use the pieces I remove to make new plants and these may not root if I do them now. So I'll wait until late February which for us is when the soil start to warm up again. Ajuga on the other hand seems to root quite readily so I am levering up rooted runners and potting them up or moving to a new spot now. Some the ground cover Campanulas (e.g. punctata) disappear below the ground over winter so leave these alone now and leave a few dead flower stems on to show their position. We lifted and divided our Corydalis in late September / early October. I never tried doing them this late but if you merely want to curtail the size of a clump you could do that now. Centaurea can be cut back hard to the ground and it is a good time to find any slugs and snails hiding in the leaves. Euphorbias are a bit trickier. Ones like myrsinites or rigida that remain evergreen are best left alone and any cutting back done in late winter to remove any damaged or rotting stems (beware the sap!). If you have any of the really invasive ones now might be a good time to try and get the roots out as many send out new underground shoots over winter. With Geums, just remove dead leaves and flower stems. I leave Saxifrages until spring and see if there is any rot after winter. For Sedums remove the dead flower stems - cut right back to the ground or just above the new plantlets clustered round the stems. Veronica gentianoides is one of those plants where old leaves turn mushy in winter so it is best to remove these. The trailing stems are covered with fresh root which suggests that they could be transplanted now but we have had little luck with transplants in pots in the open air over winter.

Woody Plants: Some of the plants we grow as perennials are woody plants and may need pruning to improve structure, shape, flowering for next year. There are (as far as I am aware) no defined methods of pruning like there are for Roses, fruit trees and bushes, Wisteria or Clematis. In our garden several woody "perennials" spring to mind. The Salvias I leave be until late winter / early spring and then I cut them back to a neat framework, taking out dead stems (by dead I don't mean leafless - if the stem is still green inside its alive), badly shaped or broken ones. Then I prune to give a good shape. I cut most of these woody Salvias back quite hard because they will make plenty of new growth during the season. I'd also leave Helianthemums until spring and cut them back with secateurs or shears then. I don't prune Cistus into old, bare wood as they rarely resprout. But now is a good time to take cuttings and this will serve to make the plant bush up in spring. Cut off 3-4 inch long sections with a sharp knife and pot up in gritty compost.  Hydrangea Annabelle is a woody shrub. When cutting back cut just above a good bud if possible. You can leave it only lightly pruned - remove dead flowers and damaged or badly placed stems. For the largest flowers cut the stems back very hard - I used to cut back to about 1ft tall. Nowadays I leave her a bit taller resulting in smaller flowers but a better, self supporting plants. I cut back lightly leaving some of this years growth on the plant. Note: other Hydrangeas are treated differently but I have no experience of them. Coloured stem varieties of Cornus are not pruned until late winter as we want to enjoy them through the winter. The usual advice is to cut back very hard (say to 6in above the ground) at this time. This assumes you want to keep them as a low growing feature. I find vigorous ones like Midwinter Fire respond well to this. My preference however is for lighter pruning. I take out about a quarter to a third of the old, brown thick stems right at ground level using loppers. I then remove poor twiggy stems and those with any die-back (dead ends to the stems). I then cut back to form a pleasing shape but not necessarily too low to the grown. Midwinter Fire is best cut back fairly low. Cornus sibirica Alba with its bright red stems I cut back to about 1 - 2ft above ground. With the black stemmed Kesselringii I have been experimenting with leaving this largely unpruned in height but just thinned out of old stems (see 17th October 2009). I always cut back Anthemis tinctoria it this time of year as it stops the plants being too leggy next year.

More on pruning later. (see 8 December 2009)


Kniphofia Jonathan25th November: Kniphofia trial

We received two large boxes today stuffed full of Kniphofias returned to us by the RHS after being loaned to them for their recently completed trial.  Its definitely not the right time to propagate Kniphofia so we are keeping our fingers crossed about keeping them through winter. I've cleaned them up as much as possible, removing dead or damaged leaves and cutting back the fleshy roots as much as possible as these will only die and rot over winter. I've planted them in fairly dry peaty composts and put them in sheltered dry place. I am seriously considering packing them in dry peat in a frost free garage over winter as I've noticed that pieces of Kniphofia rhizome come out of the compost heap intact and sprouting in spring. 

On the right is Kniphofia Jonathan in our garden looking smouldering hot in front of the icy Eryngium giganteum Silver Ghost.  Jonathan performed very well in the trial and we hope to have some for sale next year.