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This spring I planted a narrow-leaved prunus laurocerasus (it could be Otto Lycken cultivar, but I am not positive). It started well and strong. However, the summer in my area was very hot and dry, and the plant was visibly shaken throughout summer months - a lot of leaves dropping, new leaves appearing. At some point it even bloomed, so it was strong, but still confused, and it still looks as if suffered a lot.

And about a month ago, a strange thing happened: New leaves started appearing from the base of the plant - and they are not narrow any more! They look like those from common prunus laurocerasus.

I have no clue what to do. Should I remove new leaves? Should I remove old leaves? Or should I just leave the plant as is and let the nature do the selection?

This is overall present look of the plant:

(branches used to be full of narrow leaves - now there are just some at the tops; at the center of the lant you can see new wide leaves)

enter image description here

Wide leaves at the base of the plant:

enter image description here

Narrow leaves at the top of the plant:

enter image description here

VividD
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  • Are those grass clippings at the base of this plant? On one hand that would be the reason this plant got a boost of nitrogen, after the decomposers had had their fill of nitrogen to do the decomposition work. Gotta look at that trunk. If these clippings are decomposing you could also be looking at faster girdling/animal damage. Make a cleared circle at least the width of it's canopy width. You might have damaged trunks and vascular systems that would over ride fertilizer as a primary cause. – stormy Oct 12 '17 at 23:12
  • Does anyone notice the difference in margins on this one plant? – stormy Oct 12 '17 at 23:13
  • Yes, I put a thick layer of grass clippings around the plant in July, to prevent weed development, and keep moisture. The clippings are now mostly decomposed. @stormy – VividD Oct 13 '17 at 05:46
  • @stormy Leaf margin is different between the two types of leaves: the cultivar has smooth edges, while the base has serrated ones. This is fine, not unexpected. – VividD Oct 13 '17 at 06:29
  • Those clippings might have caused your bark to rot reducing the health of the vascular system. Undecomposed organic matter causes a loss of nitrogen as the decomposers will use the nitrogen first, the plant might get some after decomposition. Holding in moisture...as long as it is not touching that bark at all. Still robbing your soil of chemistry necessary to the plant. The two pictures I sent are of the same plant, one with serrated edges and one without. Have you added any balanced fertilizer? Ever? – stormy Oct 13 '17 at 23:41

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Looks to me like those wide leaves are coming off of sucker growth from rootstock that your narrow leafed tree was grafted onto.

However, the main body of your narrow leafed tree doesn't seem to be dead, and looks like it will come back. My advice is to leave it alone for a while to make sure the main tree (upper portion)is completely on the road to recovery, and then trim off those wide sucker leaves at the bottom.

Lorel C.
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  • Some new growth can be even now definitely seen in upper parts, but a lot of leaves dropped since unbearable temperatures in August, so the plant looks terrible compared to its former look. – VividD Oct 12 '17 at 17:32
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I agree that the wider leaved growth is coming off the rootstock, but you should remove it immediately,at the base, as close as you can get to the rootstock. Leaving that to grow will discourage the grafted part at the top from recovering and growing anew - growth off rootstocks is always stronger than that of the grafted part, and will take over and drown it out.

Perhaps you did not water the plant sufficiently well - any new shrub or tree planted in spring and throughout its first two years will need regular water supplies (from you, if its not falling out of the sky often enough) and copious, frequent amounts if the weather is very hot and dry for any time period at all. Prunus laurocerasus (the rootstock) is extremely resilient, but the grafted part not so much. Keep it well watered next year too. This plant does well in shade or part shade, so if you planted it in a full sun position, it will need more attention to watering for the next year or so from spring up to end of October (assuming you're in the northern hemisphere).

UPDATE: Having done some research, Prunus laurocerasus 'Zeblid' (which is likely what your plant is) seems to be simply a sport of P. laurocerasus rather than a grafted plant. If that's the case,then I'm sorry to say that some genetic reversion may have taken place, caused by environmental stress, which would mean you've now got P. laurocerasus growing from the roots, and not 'Zeblid'. If that's the case, then cutting back the reverted growth should, in theory, encourage the 'Zeblid' part to grow - but it depends how much damage has been sustained as to whether it works or not. I'd cut back the reverted growth because I'd rather have 'Zeblid' or some other replacement shrub, not being a fan of P. laurocerasus, but that's your choice to make.

Bamboo
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  • The summer was horribly hot and dry at the location. The position is unfortunately full sun. Watering was 2 gallons every second day in the hottest two weeks of the season, and 2 gallons twice a week otherwise. I suspect this was not enough. – VividD Oct 12 '17 at 17:21
  • What puzzles me, are Prunus laurocerasus cultivars grafted, in general? This specimen came to my possession as a multistem shrub, with all stems narrow-leaved (the height of the plant was more than twice smaller than present height, so it did grow), and this means that if it is a grafted plant, the graft has to be under the ground. I never came across such grafts, so everything seems odd to me. – VividD Oct 12 '17 at 17:25
  • I'll confess it seems odd to me - if they're grafted,I never realised they were, but certainly, what's growing at the base is Prunus laurocerasus, and what's at the top is a different variety, so unless there's a big and very odd reversion problem, its the only explanation. Reversion usually occurs on above ground branches, and only one or two.One way to check is to dig around to see where the large leaved shoots are coming from, but that probably means damaging the rootball. If its off the rootstock, it'll be straight off the roots, and not off any branches with narrower leaves, so check that – Bamboo Oct 12 '17 at 18:37
  • If you have no objection to a shrub that will reach 25 feet by 12 feet, then let the P. laurocerasus take over if you like. – Bamboo Oct 12 '17 at 18:43
  • The do best hedged or regularly pruned once or twice per year. Otherwise, this is considered a small tree. My favorite shrub, Blue Arctic Willow, will get to 30'X30' if not pruned, headed. I've kept my 'soft' hedges of this willow for 3 decades no higher than 3-4', easily. I didn't know they grafted laurocerasus? – stormy Oct 12 '17 at 21:59
  • @Bamboo I am going to ask the nursery where I bought the prunus about the propagation. I know that even the cultivar is a large plant (I was shown the adult specimen at the nursery), a little shorter, but even wider than the basic prunus laurocerasus. – VividD Oct 15 '17 at 10:09
  • I've done some research, but as far as I'm able to discover, 'Zeblid', which is most likely what yours is, is simply a sport off P. laurocerasus, which might indicate genetic reversion is the problem rather more than sucker growth, but I couldn't find anything definitive. Be interested to hear what the nursery says... I'll edit my answer to include this. – Bamboo Oct 15 '17 at 11:11
  • And by the way, do not feed it... fertilizer is not appropriate right now, unless you're in the southern hemisphere or somewhere tropical – Bamboo Oct 15 '17 at 11:36
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What you desperately have to do is add a balanced fertilizer! Not compost or tea or fish emulsion...or epsom salts! Balanced fertilizer. Just follow directions do not add more or less than the instructions. I'd use OSMOCOTE 14-14-14, and only fertilize twice a year not 4.

Remove all the weeds around the base on the surface of the soil. Check to see the condition of the base or trunk(s). Woody shrubs will eventually die if buried too deeply; only the roots are underground, the bark of the trunk free from any mulch, weeds, soil, rocks so moisture is not allowed to stay on the bark to harbor bacteria that will girdle your trunk. Use a balanced fertilizer with N P & K. Your plant is not able to support any more leaves until it has fertilizer with which to make its own food.

Essentially, your plant is dumping photosynthetic factories. If a plant does not have access to nitrogen, phosphorous, potassium, iron, calcium, manganese, and about dozen other micro 'nutrients'...it is unable to make its own food. Your plant is starving. It's own carbohydrate storage of food can not support any more leaves and the roots are probably compromised as well. It has chosen to support just enough photosynthetic factories to survive, robbing Nitrogen from other leaves or rather mobilizing any nitrogen available to help out the failing factories left.

I think I know the brand of Laurel you have but I am not going to try to spell it without looking it up...see what you think...Prunus laurocerasus Schipkaensis See what I mean with the spelling? Schipkaensis Laurel

This is a better picture although this plant is in desperate need of fertilizer as well. See the color in the first picture? That is what your plant should look like, a bit lighter because you are in full sun but not this color. Add 'Macrophylla' which means roughly 'I have fatter leaves than my cousins'? Prunus laurocerasus Schipkaensis Macrophylla Schip Laurel

Note: Don't remove ANY leaves...yet. That plant is down to its last reserves. Those factories, the green leaves are all that are supporting this plant, making the food necessary for all functions! Without those factories you can forget about fertilizing. Fertilizer are critical chemicals those factories need to convert sunlight into food...food for the plant itself. Without factories you won't need support supplies. Don't take those factories off just yet.

stormy
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