If the dead area is, say, along one side of the garden only, you could replace just that side and leave the other side for now. I don't think I'd put more of the same in the same spot if it was a disease that's caused the dieback, but that's up to you if you want to try it as a least-work-and-cost solution, or if you think it was environment/cultural rather than disease (eg drought or cutting back too hard) and you can't see any sign of it spreading beyond what's in the first picture. Either way, improve the soil before replanting because leylandii will have taken all the goodness out of it.
Doncaster, South Yorkshire. Soil type: sandy, well-drained
I don't think the dieback was caused by cutting back too hard. The close-up photo of the dead section shows that branchlets with needles on have died, suggesting disease, waterlogging or lack of water. (They need well-drained but moist soil, and don't cope well with prolonged drought or excessive wet.)
Has anything else in your garden died recently? Honey fungus will attack leylandii, but you'd expect to see other susceptible shrubs in the area dying or dead if that was the case. You might also see clumps of honey-coloured fungi around if that was the case.
As @Dovefromabove says, the Cypress aphid can cause brown leaves and dieback. There are also fungi which attack Leyland cypress, including phytophthora root rots and cankers.
It's a real shame because that's a lovely hedge... but you may not get away with replacing the dead section with more leylandii, unless you're sure the problem is caused by too much or too little water in that area, and you can address that in future.
Since 2019 I've lived in east Clare, in the west of Ireland.
Because it has died in place, you could send beautiful rambling roses or heavenly scented jasmines over it, using it as a structure. That means you will have a beautifully flowering and lovely scented hedge. You can strengthen the structure in place by hammering down some poles into the ground through the dead part about 2 feet apart.
Jasminum Officinale is a heavenly scented climber that will attract bees.
The soil is kinda sandy and i allowed Ivy and weeds to grow there through my own laziness and inattention. I wonder if that could have lead to a lack of water?
Re replacing just this side wouldn’t it look a bit odd to have one type of hedge on one side of the entrance to my house and another on the other side?
Here is the stuff that grew below which I’m now removing bit by bit.
also, all your replies have helped to make a sad person get a bit of perspective and not feel so lost. I really appreciate it.
Train up some Jasmine Officianale, heavenly scented and attractive to bees.
They are tender until established. So, one should first grow them in pots for the first year and take the plants indoors for the first winter. Then plant them out about April (when the first frost has passed) and train them up the hedge. Soon you will have a heavenly scented hedge with little white flowers buzzing with bees and butterflies.
Train up some Jasmine Officianale, heavenly scented and attractive to bees.
They are tender until established. So, one should first grow them in pots for the first year and take the plants indoors for the first winter. Then plant them out about April (when the first frost has passed) and train them up the hedge. Soon you will have a heavenly scented hedge with little white flowers buzzing with bees and butterflies.
@jac19 When you say train up do you mean Jasmine near the base of the sections of hedge that are dead and let them climb over the dead hedge?
Train up some Jasmine Officianale, heavenly scented and attractive to bees.
They are tender until established. So, one should first grow them in pots for the first year and take the plants indoors for the first winter. Then plant them out about April (when the first frost has passed) and train them up the hedge. Soon you will have a heavenly scented hedge with little white flowers buzzing with bees and butterflies.
@jac19 When you say train up do you mean Jasmine near the base of the sections of hedge that are dead and let them climb over the dead hedge?
Be aware that, quite apart from any other issues about growing it in this situation, which I am not qualified to pass comment on, Jasmine Officinale is deciduous and won't provide the screening you have from the rest of the hedge for half the year.
I don't think it would look odd to have different hedges on each side. Unless the whole street has leylandii, someone must have different things on each side.
If you want to go down the route of a climber to cover the brown areas, the easiest thing would be to encourage the ivy that's already growing in the base on the hedge to grow up. It's tough and evergreen, and won't mind if it gets clipped along with the rest of the hedge. It's quite hard to establish anything new in the root zone of conifers.
Doncaster, South Yorkshire. Soil type: sandy, well-drained
In fact, I am having a hedge plant killed in place this autumn, so that I can do this -- send Jasmine Officinales up and over it, using it as a structure. I have the Jasmines earmarked for this growing in pots right now. Flowers Bees The heavenly scent
Posts
Has anything else in your garden died recently? Honey fungus will attack leylandii, but you'd expect to see other susceptible shrubs in the area dying or dead if that was the case. You might also see clumps of honey-coloured fungi around if that was the case.
As @Dovefromabove says, the Cypress aphid can cause brown leaves and dieback. There are also fungi which attack Leyland cypress, including phytophthora root rots and cankers.
It's a real shame because that's a lovely hedge... but you may not get away with replacing the dead section with more leylandii, unless you're sure the problem is caused by too much or too little water in that area, and you can address that in future.
Jasminum Officinale is a heavenly scented climber that will attract bees.
When life throws lemons at you, make lemonade.
Re replacing just this side wouldn’t it look a bit odd to have one type of hedge on one side of the entrance to my house and another on the other side?
Here is the stuff that grew below which I’m now removing bit by bit.
also, all your replies have helped to make a sad person get a bit of perspective and not feel so lost. I really appreciate it.
ps first pic is rotated 90 degrees for some reason
They are tender until established. So, one should first grow them in pots for the first year and take the plants indoors for the first winter. Then plant them out about April (when the first frost has passed) and train them up the hedge. Soon you will have a heavenly scented hedge with little white flowers buzzing with bees and butterflies.
In fact, I am having a hedge plant killed in place this autumn, so that I can do this -- send Jasmine Officinales up and over it, using it as a structure. I have the Jasmines earmarked for this growing in pots right now.
Flowers
Bees
The heavenly scent