Autumn blues

We've had a spell of unseasonably warm weather just recently.  Not hot - this is South West England in mid October - and not too sunny but very mild and very pleasant.  With cloud cover has also come relatively warm nights.  The result has been a final flowering of a number of my more tender plants.  Amongst them being a small collection of blue flowered (often tinged with red and purple) specimens.  Collectively they are adding a lot to the Autumn scene.

Blue isn't that common a colour in cool climate plants so I'm glad to have a number that not only survive but thrive in the garden.  Mind you, I could do with a few more - but more of that later.

One to really benefit has been my plant of Ipomea indica.  After breaking ground in May it grew steadily to cover part of my south facing wall before beginning to flower in early September.  Normally, cooler nights at this time of year restrict flowering to the production of no more than one bloom at a time at three to five day intervals from each of the spiky clusters that develop in the upper leaf axils.  Maybe 6 to 8 at a time on the whole plant.  With the warmer nights I'm getting two and three blooms at a time from each cluster, giving far more concentrated colour.  It's not a big plant (compared to the size it can reach in warmer climates) but I counted nearly thirty blue trumpets this morning.  Glorious.  And very encouraging for a plant that all the authorities insist isn't hardy in the UK except in the very mildest of spots.  My garden isn't that mild!

Ipomea indica - mid October flowers

Ipomea indica - another cluster of mid October flowers

Meanwhile, down on the ground underneath the bare stem my nicely maturing plant of Yucca gloriosa 'Variegata', the carpeting Convolvulus mauritanicus now covers about 10ft sq / 1 metre sq and continues to produce good quantities of similar but smaller blue trumpets.  Unlike the Ipomea these last longer than a single day but fold up by late afternoon to re-open the next morning.  It's a pretty little thing and, although I've seen plenty of doubts about hardiness, has survived the last ten winters with me.  It dies down to a small rootstock in winter - just like it's larger cousin - but soon spreads outwards with the warmer weather of later spring.  Once it starts flowering, usually in June with me, it's continuously in bloom.  The warmer the weather, the more flowers - so this display so late in the growing season is a welcome sight.

Convolvulus mauritanicus

Similarly long flowering is Ceratostigma willmottianum.  This wiry stemmed little shrub is adapted to drier summers than we usually experience in Plymouth and this year's display hasn't been that brilliant.  As soon as individual flowers begin the emerge from the spiky terminal ball at the end of every shoot they've been rained on - and it's not something they appreciate.  But, finally, a few days of settled weather has allowed full blown clusters of small blue flowers to adorn the whole bush and it's looking wonderful

Ceratostigma willmottianum

In colder areas it will function as returning perennial, regrowing from the roots after losing the top growth to frost.  With me it usually retains a woody framework.  I prune this in spring to remove damaged stems and let the plant romp away to its current 3-4ft / 90-120cm height.  Although it seems more than happy on my acid, rather stony soil, the one thing I don't get is the red autumn colour so often described as accompanying the flowers at this time of year.  A few red leaves, but nothing significant.

Tibouchina organensis

I mentioned Tibouchina organensis in the last post.  The flowers are more purple than blue but I think it still qualifies for this piece.  Flowering is now building up nicely and hopefully will continue until icy weather forces me to bring it under cover.  I've got a nice spot in the kitchen picked out - though Maria might have other ideas.

I've had the chance to visit a few gardens recently and two other autumn flowering blues have caught my eye.  Oddly enough, I've grown them both in previous gardens but not in my current one.  The first is Gentiana asclepiadia, the willow gentian.

Gentiana asclepiadea

Gentiana asclepiadea

This is a shade tolerant, tough and pretty reliable perennial that makes about 2-3ft / 60-90cm of annual growth and finishes with an autumn display of true gentian blue flowers.  I'm clearing an area in my front garden and the open shade and moist soil will suit it perfectly.  Number 1 on the 'to be ordered' list.  (There's a white form but it doesn't have the same impact.)

Number 2 on the list is Aster x frikartii 'Monch'.  Unlike other autumn asters of the novi-belgii  and novae-angliae this one is a true blue, disease resistant, and can flower from August onwards well into late Autumn on a neat, well branched plant that rarely needs any support.  I was very pleasantly reminded of it's potential when I visited Bodnant garden during a recent visit to North Wales.  No wonder that great gardener and gardening writer Graham Stuart Thomas rated it amongst his top 6 perennials.  I reckon I can provide the well nourished soil and sunny space this one needs to thrive if I just clear a little bit of the rather rampant Iris sibirica in the top border in the front garden.

Aster x frikartii 'Monch'

Mind you, with all of these it's so dependent on the weather for a good display.  And it looks like we may be getting the first cold spell coming in for the weekend.  Time to start moving my seriously tender plants from the little shade house to the warmth and shelter of indoors.  But that's for another blog post.

Update 24/10/2012:  I've just realised that I've used the old, no longer valid name Convolvulus mauritanicus rather than the correct C.sabatius.  It is the same plant.  Honest.