Cuttings - when and how

Can anyone advise me when and how to take cuttings of penstemon and lavender?

I intend to root them in a jar of water on the kitchen windowsill. Is it too early now or should I wait til september time? If I have success should I keep them in over winter as I have no greenhouse. Perhaps the utility room - no heating but not as cold as outside?

Exactly which parts of the plant make good cuttings? Excuxe all the questions, but I am new to this and feel like my brain is a gardening sponge! :gnthb:

 

About now sounds a good time, have a look at this link

http://www.gardenersworld.com/how-to/projects/lavender-cuttings/

 

It says access is forbidden!

 

Hi Vicki,

I have always thought highly of the RHS how to pages.

http://www.rhs.org.uk/advice/profiles0804/lavenderrosemarycuttings.asp

 

Chris Beardshaw :luv: explains lavender cuttings very clearly about a minute into this video

 

Thanks for putting the video up - very useful

 

Penstemons are the simplest things to grow from cuttings - so simple even I've done it.

Pick off some non-flowering shoots about 4 - 5" long, remove the bottom leaves and with a sharp knife, trim the bottom of the stem to just below a leaf node. Dip the cut end in some hormone rooting powder, tap off the excess and insert in a 3" pot of pre-watered compost - I used 50/50 John Innes Seed compost and perlite with 4 cuttings around the edge.

Some people may suggest you cover them with a plastic bag to make a micro-climate, but I just left mine uncovered, (standing in an old plastic container in about 5 mm of water) under a garden table.

That was about 5 weeks ago and there are now tiny roots appearing at the bottom of the pot. I shall wait another couple of weeks probably, then pot each one separately and leave them in my unheated greenhouse over the winter.

 

I took some lavender cuttings and followed the advice in the video to the letter.......and I lost the lot!:( So then I took some more cuttings and just pushed them into the pot alongside my large lavender plant.......and they're thriving.

 

Here's a video on taking semi-ripe cuttings,
http://www.youtube.com/user/ShootGardening

 

Thanks Walnut for the video - its always nice to see it done rather than read about it.

I note the very high level of hygine - always sterilising the knife. Then dipping all the cuttings into the same pot that all the other diseased cuttings have been dipped in. :D

But seriously - a good video.

But I am interested in the watering aspect. Cuttings can't really adsorb any water until they grow roots, which will be some time. So why water them at the start - as water can only cause rot at that stage? Thats not a criticism - just a question that no-one has ever answered. There may be a good reason.

 

Peter said,

They do take up water Peter but at a greatly reduced rate,transpiration still occurs from the leaf of the cutting water is drawn into the cutting albeit at a greatly reduced rate by the action of osmosis,enclosing the cutting in a polythene bag slows this process down and the leaves stay hydrated and not limp as they would without the poly cover, in effect you slowing the" working"of the plant to suit its uptake until new roots can take over.

 

I suspect that they might draw up a little water at the end of the stem, in the same way that cut flowers do. But presumably once they have calloused over, which she explained was the first to happen, they can't draw up much. Osmosis really only works through very thin membranes.

I totally agree about enclosing in a polythene bag. In fact when I take cuttings I use a heated propagator and flood the base with water. This produces 100% humidity, so there is no way that the plant can suffer from loss of moisture. Rot is a different matter, but I have never had that yet - touch wood.

 

How long do you leave them covered with a polythene bag? My first set of cuttings dried out so i have taken another lot and covered with a bag and secured with elastic band - i'm hoping i have more luck!

 

When you first make a cutting, it has no roots. So it can't draw up any moisture from the compost, except perhaps a very tiny amount adsorbed through the stem. So you need the polythene bag to preserve what moisture there is. You can only remove the bag when the roots have grown sufficient to draw up moisture for themselves. It depends how quickly the cutting makes roots, but it won't be less than 10 to 14 days, and could be more.

When the cutting starts to grow new leaves, is generally a sign that it has made some root. But sometimes cuttings can grow new leaves and not have any roots. One way is to take more cuttings than you need and to extract a cutting at intervals and inspect. In the past I have had a pot of cuttings and after say 14 days very gently taken it apart to see the state of growth of the roots. Those with good root growth I then potted up individually and those without I potted up again and re-covered. I am not really suggesting this as a viable method, but I do it quite often as an experiment to see how much root there is after a certain period. However I don't think I ever lost any cuttings by doing it.

When I take cuttings of Salvias, with bottom heat in a propagator in a light box in late summer, the normal progress is that nothing happens for 8 to 10 days. Then roots grow quite quickly over the next 4 to 6 days. I can have fully rooted cuttings after as little as 10 to 12 days. Cuttings need good light, but don't want to be in direct sun as that will dry them out. But other plants may take longer.

Its usually advisable to have a small hole in the bag to reduce the chance of rot. As new leaves appear you can increase the size of the hole to effectively remove the bag slowly.