Posted: 10/05/2013 at 00:11
Have just apparently succeeded with some hardwood(ish) cuttings of perovskia (Russian sage), to my slight surprise but pleasure, having stuck ten or eleven woody stems about 6" long — taken from pruning two existing plants about a couple of months ago — into a largish (c. 8") pot in the greenhouse and covered it with a plastic bag from the greengrocers, propped up tentpole-style by a stick in the middle. Watered well before I put the bag on then left to its own devices — bag was entirely unperforated so it's stayed damp in there, a proper little microclimate — and merely switched to a clean bag about three weeks ago when I saw the first signs of green through the condensation within. Removed this second bag altogether this week to allow the light and air in better now it's a good deal warmer, and gave it a proper water. Five stems are putting out good green growth, while the others have not done anything but I'm leaving them in place for now as know from experience that perovskia can suddenly surprise you just when you've decided it's dead wood! Managed to root three short stems in a small pot last year, but planted them out too soon and they got swamped by other things, so will leave these to grow on for a good while first seeing as they've got plenty of space. Curiously, only success I've had before is the happy accident that gave two current plants in the first place — inadvertently snapped a stem off the original while transplanting in summer four or five years ago after it got overcrowded in its previous site, and on the off chance just stuck this into the ground as it was and thought no more about it...and of course it rooted next to its parent and took off quite happily! It's amazing how many of the best results come from this sort of thing, or forgetting things entirely ‚ have just discovered that I have a small pot with a cutting of variegated aubretia in the greenhouse, which I've only identified in the past fortnight after it sprang into growth...
Other current successes include seed tray of 30 or so lavender prunings in the greenhouse, taken maybe a month ago and which I've just taken the clear plastic lid off as they all look to have rooted so could now benefit from a less actively humid environment. Got a good load of cuttings from same lavender ('Munstead') last year too without 'hothousing' them in this way, i.e. just in uncovered pots, but think these new ones have probably taken a little more readily with the extra humidity to start with. Planted some out with good success, while a dozen smaller ones were kept in greenhouse over winter and now potted up singly to grow on and give away in a couple of weeks' time.
Both last year and this have taken prunings from santolina (cotton lavender) at the same time as the lavender, start of April, and found they root readily as well in uncovered pots as not great fans of humidity at all. Used similarly small shoot tips to the lavender (maybe 2") last year, but this time am trying to get slightly larger santolina cuttings to root so selected some larger prunings, so have one small tray with nine cuttings about 3" high and another with half a dozen 4" ones. As these are woodier they're not rooting so fast, but showing signs of new growth so I'm reasonably happy so far. Last summer was able to make a nice border for newly laid out bed in sunnyish, dryish and wall-drained front garden, by planting out row of alternating lavender and santolina cuttings from that spring, which grew in together to make a rather lovely silver whole, and are putting on good new growth again now after cutting back a month ago.
Also on the silvery side, had three Plectranthus argentatus from my grandad the year before last, which isn't hardy enough to last the winter outdoors but which he always takes cuttings from in summer to keep