We had our first proper frost this week, down to 30F (-1C) with a good solid crust on the birdbath. Fortunately, we were warned and were able to take precautions – so out came all the old bedsheets.

The cannas, bananas, coleus, plectranthus, impatiens, begonias and the rest – in containers as you can see on the deck and out in the garden –they all got the bedsheet treatment. And it worked just great.

OK... it looks a bit weird. But who cares? You can see in the second and third pictures the difference between the white impatiens which were covered and those that escaped. Those which were exposed to the frost are reduced to a soggy mess.

The bedsheets then went briefly into the drier and are now ready for the next frosty forecast on Sunday night. But it’s looking good, and that one night of cover should give us colour for the rest of the week.

A few weeks ago I mentioned the startlingly scarlet Lobelia cardinalis (cardinal flower) growing by our little stream. Well in the garden there’s lovely wild variant. As you can see it’s a soft rose pink, shading to white at the base of the petals, the flowers opening from coral pink buds.

This came to me from Georgia native plant wizard Don Jacobs, whom I’ve mentioned here before. He’s spent decades searching out natural variants of native plants and this is a real treat.

Growing in soil which is less damp and less rich than is ideal it’s steadily getting stronger and is still has a few final flowers here at the end of October. It will be interesting to see if the bees take pollen across to those wild ones fifty yards away. I’ve made a point of not growing the sophisticated hybrids bred in Germany – the Compliment and Fan series – superb though they are as I didn’t want the wild ones to be contaminated. Rightly or wrongly, if pinks turn up by the stream I don’t think I’ll mind at all.

One of the big wholesale growers now has 'Eco Pink Flare' in production, so look ouit for it in nurseries and with mail order suppliers next year.

Recently I’ve been working on an article about the new hybrid echinaceas for the Royal Horticultural Society’s Plantsman magazine. These are the orange and yellow hybrids like ‘Orange Meadowbrite’ and ‘Harvest Moon’ as well as others not even released yet. I grew all the plants, and talked to all the breeders.

One of the breeders I talked to was Charles Valin at Thompson & Morgan - you can see a slide show his plants here but let me emphasise that they're not yet available to gardeners or growers – this is an exclusive sneak preview. T&M is the only British seed company with, like myself, a presence on both sides of the Atlantic – alongside their extensive British operation they also have a permanent staff in the US and a special US version of their catalog and website.

For many years T&M have been breeding new annuals and perennials for their seed catalog - I’ve visited their breeding station many times. They’ve met with increasing success and their plants have won many awards. In recent years they’ve also been working on new plants intended to be raised from cuttings or in the laboratory by tissue culture as well as from seed – and one of their current projects is echinaceas.

They’re creating some impressive plants, as you can see from the slide show here. Some have reached the stage of being assessed for possible introduction on both sides of the Atlantic so I hope for news next year of when the first will be introduced.

So check out the slide show here and as soon as my article in The Plantsman is published, I’ll be sure to let you know.

Like most news organisations around the world the BBC asks its readers, listeners and viewers to send in their own pictures. Of course, people send in their snaps of local incidents and events – but about half the pictures the BBC receives… are of cats.

Recently, when they asked for pictures illustrating an especially stormy spell of British weather – what did they receive? Pictures of soggy and bedraggled cats.

OK… this is a gardening blog – so it’s about time for a picture of one of our cats. This is Nicki, not horticulturally helpful but undeniably charming, relaxing on a trough of ‘Sorbet’ violas. Fortunately, she didn’t discover the comfort of this location until the end of the season – shortly before the violas were removed!

Well, as the trees are just passing their full fall splendor here in north east PA it’s easy to forget that fall foliage color is also a feature of some excellent perennials. One of the best for fall color is one of the bluestars, a US native from just two states (Oklahoma and Arkansas), Amsonia hubrichtii.

Its common name comes from its summer starry blue flowers, rather like those of the Vinca (periwinkle) to which it’s related. But its chief glory is about now when the whole mass of slender foliage turns bright and buttery yellow. With Physocarpus ‘Coppertina’, which looks to be the best of many recent new shrub introductions and whose foliage turns bronzy purple in the fall, the amsonia would make a great picture. Add a ruby, rusty or coppery Korean chrysanthemum like ‘Ruby Raynor’ or ‘Lucy Simpson’ or ‘Paul Boissier’ and you’ll have a combination that’s more than a match for the fall lcolor in the trees all around.

The fall foliage may be the most spectacular feature of both the garden and landscape at this time of year, but outside my window here in PA a little treasure is in full flower.

The nodding lady’s tresses, Spiranthes cernua, is a native orchid that grows across a wide range of the US, from the eastern seaboard across to Texas, Kansas and Nebraska. I didn’t dig mine up from the wild, I should say, it came from native plant specialist Don Jacobs of Decatur, GA.

This year it’s noticeably taller than last, about 18in/45cm as against about 12in/30 in its first season last year. I have to say I gave it a dose or two of MiracleGro during the summer which I wouldn’t do for with most orchids! The white flowers are clustered towards the top of the stem – the picture covers about 2in/5cm and shows the spiral arrangement of the flowers. In the wild it grows in damp places – fields, meadows, along streambanks and lakesides as well as in roadside ditches. You can see more pictures on the USDA plants website.

The unusually vigorous and fragrant cultivar ‘Chadd’s Ford’ was found in a Delaware ditch and you can buy it from Sunlight Gardens.  In fact the native fragrant form, from the south, is sometimes distinguished as var. odorata - you can order it from Plant Delights.

This is one of the easiest of all orchids to grow out in the garden – otherwise it wouldn’t be thriving in the terrible soil we have here – and it’s hardy too, down to zone 4. And it seems to like MiracleGro!

Finally from my recent visit to Yew Dell Gardens near Louisville, KY – a very rare variegated plant that I found out in the arboretum.

The variegated form of the English oak, Quercus robur ‘Variegata’, is only listed by two nurseries in Britain and very rarely seen in the US. The one in the Yew Dell arboretum was looking rather sad after the summer drought but it had opened a few fresh new leaves so the marginal variegation could clearly be seen. It's unexpectedly attractive.

There are a number of variegated forms of this tree – with foliage splashed, mottled or edged in cream, yellow or pale green – but the names seem muddled and as far as I know no one has sorted them out and matched each type of variegation with the correct name. This cream edged form is sometimes listed as ‘Argenteomarginata’.

At the Royal Botanic Gardens at Kew there is, apparently, a tree which produces green leaves in spring and then when its second flush of foliage appears later in the season the leaves are variegated. I've never heard of such a curiosity before and unfortunately I don’t remember seeing the tree when I was at Kew – although I certainly remember the golden-leaved form growing not far from The Orangery.

There must be some variegated forms of American oaks out there too…

Roaring back to the Louisville airport after the AHS Garden School, a flash of gold caught my eye by the roadside. The cab booked by the hotel had not arrived (thank you YellowCab of Louisville) so one of the hotel staff drove me to the airport – he spoke little English and had never been to the airport before! So when I spotted a grove of golden stems by the side of the freeway, trying to make him understand that I wanted him to stop to take a look didn’t seem an option – and, anyway, by then I was late for my plane.

When I got home I checked on the USDA Plants Database which gives distribution maps for both native and non-native plants and it looks as if the familiar Golden Bamboo, Phyllostachys aurea, grows nowhere in KY or nearby while the Yellow Grove Bamboo, P. aureosulcata, grows in a couple of KY counties, but not near Jefferson County, where I saw it alongside I-71. What's more, only the ‘Aureocaulis’ form of P. aureosulcata has stems which are completely yellow, and they are more a yellow color than the golden orange of P. aurea. Perhaps it was P. aureosulcata ‘Aureocaulis’? I’m not sure.

So… is this a new sighting? Whichever species it was there was quite a lot of it but flashing by in a rush to the airport with trucks spoiling the view it was impossible to be sure what it was. Any thoughts, anyone?

One of the highlights of the recent American Horticultural Society’s Garden School at Yew Dell Gardens, near Louisville KY, was a trip to see Cave Hill Cemetery in Louisville. A cemetery… why? Well, because its 296 acres are home to some magnificent trees.

One of the largest, and most interesting, is a maidenhair tree, Gingko biloba, planted in 1830 – eighteen years before the area was dedicated as a cemetery. Now with a spread of 130ft and a circumference around the trunk of 18ft it has grown into a splendid specimen – with one unexpected quirk.

The gingko usually produces male and female flowers on separate trees and males are usually planted, especially as street trees. This is because the yellow, plum-shaped fruits smell extremely unpleasant when they fall and are squashed by traffic.

The tree at Cave Hill is a male except about ten years ago just one branch mutated to female – so almost the whole of the tree produces male flowers except for one small part which carries female flowers and then fruits.

There are many more fine specimens of unusual trees, and twenty six of them are the largest of their kind in the state. The cemetery is open, at no charge of course, every day. Guided tours are also available. Visit the Cave Hill Cemetery website for more visitor information.

I’ve been taking look round the delightful garden at Yew Dell, just outside Louisville, Kentucky, in preparation for the American Horticultural Society’s Garden School which opens there today. And I came across one of the most striking new perennials to be introduced in recent years.

‘Low Down’ is a very dwarf and very prolific form of a huge perennial, Helianthus salicifolius, which can reach 10ft/3m in height. At Yew Dell’, ‘Low Down’ reached little more than 15in/38cm and is covered in brilliant yellow daises.

‘Low Down’ was raised by one of the world’s finest plant breeders, Dr Keith Hammett from New Zealand. He’s also produced some superb sweet peas, wonderful yellow clivias and many fine dahlias as well as other plants. Look out for ‘Low Down’, and for its sisters ‘First Light’ and ‘Table Mountain’ in mail order catalogs and nurseries.

Often listed under H. angustifolius, Dr Hammett tells me they are, in fact, forms of H. salicifolius – as the slender foliage indicates. All three are well worth growing.