Pruning Lambs Ear and Lemon Carpet Thyme in Early Spring
Answered by: Conrad Richter
Question from: Gigi
Posted on: March 24, 2000

I have planted a few heads of Woolly Lamb’s Ear in my flower bed last year. When and how should I prune them? They have grown too close together and I want to separate them a little further; should I dig them up and re-plant them now or should I wait?

With the weather as mild as it has been in your area (late March, Richmond Hill, Ontario), you could move your plants now. The key is whether or not the ground will freeze solid and thaw out repeatedly between now and the onset of spring growth. With the climate seemingly getting milder in the Greater Toronto area in recent years, it seems like there is little chance for the heaving frosts that would damage your plants. So, yes, we think you can safely move your plants now. You will have to water to help settle the soil in and around the root ball, but then you should not have to water again until you begin to see growth. Once growth is beginning to show, you should water once at least, and only again if the plants are showing signs of stress from drying out (wilting).

By pruning, I am assuming you mean cutting back the dead foliage from last year’s growth. Either that or you mean cutting back the sprawl of the plants at the roots. The dead foliage can be cut with a sharp knife at just above ground level and removed any time. It is easier to do this now before new growth appears. Woolly lambs ears is what botanists call a herbaceous perennial, which means that the plant does not have woody stems that persist from year to year like a shrub or tree does. Trimming the sprawl of the plant at the roots could be done now, but you may want to wait until the new growth appears to be sure of what has survived the winter. As soon as you see new growth, you can take a sharp spade or shovel and around the perimeter of the zone you want the plant to be in, and remove the roots and shoots from outside the perimter. Lambs ears is pretty tough, so you can afford to be rough with it during this operation.

Could you also tell me how to prune my Lemon Carpet Thyme?

I assume that the thyme has formed a carpet and you want to trim back the growth at the perimeter. You can do the same with thyme as I have described for lambs ears: use a spade to trim the area where you want the mat to grow.

You could also be referring to a thick mat of wiry stems persisting from last year. Thyme is actually a shrub in the botanical sense because it forms woody stems than can persist from year to year, and in some varieties new growth will emanate from those stems in spring. You could cut back the wiry stems if you want, but I don’t think that there is any need except for cosmetic reasons.

Occasionally, thymes get so thick with growth that the crowded stems develop diseases and eventually the centres rot away. This is more of a problem with the upright thymes such as english thyme (Thymus vulgaris) and lemon thyme (T. x citriodorus). If this is happening – and you won’t know until late spring or summer – you should thin your plants. With a spade, cut through the thyme patch, lift parts of it, and replace the open areas with fresh soil. Or, lift the whole patch, replace the lifted soil with fresh soil, and replant with divisions from the lifted plants. This thinning operation is often necessary every 3-5 years with perennial herbs in the Labiatae (also known as the Lamacieae) family; these include lavender, sage, savory, hyssop, mint, thyme, and many others.

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