Fertilization best based on soil test results. If foliage color good probably not needed, these are seen growing all over in this region - often rankly, to the extent they may break up under snow loads or be toppled by high winds. This last is probably due in large extent to the prevalence of root deformities caused by careless container culture during commercial production operations.

For wall-like density and comfortable size annual shearing will need to be undertaken. Natural habit often partially transparent - and always huge unless restrained with pruning.

Faster growth will result in greater transparency.

Understood that fertilizer not NEEDED for my Leyland but I want to do anything I can to maximize how fast they grow so anyone have any suggestions of specific type of fertilizer to give a try on some of them and when to apply? I could apply to some then compare over a year those and ones not fertilized to see if had any effect on growth.

At this point I'm much more interested in height than I am 100% dense wall of them due to my house being two story I can see all neighbors from second story, want them to get tall and at least partially obscure neighbors then over time can shear to get them more dense.

There is plenty of room for them to spread out (I'm on an acre) so not concerned about comfortable size.

in just about any decent soil ... trees NEED nothing .... but PROPER watering until fully established ...

as noted.. a soil test will tell you how decent your soil is ...

a tree is established.. when it has achieved its annual growth rate.. with no help ...

trying to exceed its genetic growth rate thru steroids.. or fertilizer .... is not really going to happen ...

if your son wanted to play football ... you would feed him what he needs to be strong and grow ... you would not double or triple his food intake.. hoping he will grow twice as big.. nor would you offer him steroids to get bigger... [or maybe you would] ... why are your trees any different ...

all your trees really need.. is your patience ....

ken

Let's make it really clear - attempting to accelerate growth is not a valid reason for fertilizing. This type of fertilizing is usually counterproductive, promoting weak, unstable growth that is more prone to environmental stress as well as increased vulnerability to diseases and pests.

It's a bit naive and unrealistic to assume that trees need no fertilizer, however. Cultivated soils are often nutrient deficient and competitive planting can also deplete nutrients. And these should be replaced for optimum growth and plant health. Whether or not this is something you need to address in your particular situation can only be determined by a soil test. The longer a tree is established, the less supplemental fertilization comes into play or becomes necessary as the expanding root system can generally access whatever is needed in the soil. Mulching with compost during the early years is often sufficient to supply any needed nutrients that may be lacking and that can be applied at any time, keeping it well away from the trunk as you would with any woody plant.

Have a professional soil test done. If the results indicate a need for nutrient supplementation, do so according to the instructions provided, no more. Mulch properly and water well as needed and then exercise patience. Plants, if given the proper care, will (and should) grow according to their schedule and genetic programming, not yours.

Forgive me if I'm telling you what you already know.

In ten more years, your Leylands will be 40' tall. If they're planted on the south side of your property, you will have a very shady area adjacent to them. In the winter, the area of your property directly north of the Leylands will get no sun at all, perhaps to a distance of 60' or so (I'm not sure exactly what the sun angle would be so far north of me). And they'll keep growing at 3' per year.

If the Leylands are on the north side of your property, you're creating a shade nightmare for those neighbors. (Ask me how I know this.)

The oldest Leylands in the world are 130' tall and still growing.

Some years ago, a most intelligent person said to me :"If you don't get on with your neighbours...move". Given my average state of intelligence, I didn't. Growing extraordinary Mexican cacti wich grow about 1 mm (1/16")a year hasn't helped much to make THEM go away.Peace comes when you find...It, hope so for you! T.
PS Yesterday I was going to suggest you buy a bag of urea-pure nitrogen N,but then I am confronted every day with this "Italian Cypress"(Cupressus sempervirens) wich grows near our greenhouses wich has served as a convenient place to answer the call of nature for some fifteen years....sappy growth indeed, but the top blew off during a storm ,leaving It (and myself) a little.. err .. topless!

Tunilla you made me laugh, little too much information there...

Wow, I'm pretty shocked at the judgmental people on this forum who have no idea what they're even judging! I've been accused of shading out neighbors, hating my neighbors, etc. NONE of which is true! People need to take a chill pill. I suspect some of these people complaining probably live on tiny lots and have been burned by large trees such as Leyland being planted but I'm in a neighborhood of acre lots, no fences, lots of room.

I appreciate the feedback received to my actual question and what I get from it is to get a soil test and possibly add compost.

Regarding soil test, recommendations most economical way to do this? I'd imagine soil conditions could vary a lot and I have these spread around many DIFFERENT places on my acre lot so I'm not sure how realistic it is to sample soil at ALL of them since they're spread in really different areas of the property whose soil likely varies. Any tips appreciated.

I went to the Washington State extension service website and copied this for you. It doesn't look like the extension does their own testing (Colorado State University has a testing lab that I use).
Copy and paste this, I think it'll answer at least some of your questions.
http://county.wsu.edu/king/gardening/mg/factsheets/Fact%20Sheets/Soil%20Testing%20and%20Soil%20Improvement.pdf
Barb

If you are most concerned about the soil conditions and the availability of nutrients specifically for the Leylands, then take your soil samples just from those areas these trees inhabit. Yes, the nutrients levels may differ from location to location throughout the property but it is unlikely they will differ substantially enough to make a significant difference on what you may need to supply, if anything. Soil testing labs generally suggest that for landscape purposes, you take multiple samples from different areas and mix together for submission.

If the trees seem to be growing well (although maybe not quite as fast as you'd like :-)) and have good color, then mulching with nutrient-rich organic matter - like compost - may be all that is required. Wood based mulches, while commonly used for trees, break down very slowly and therefore release any nutrients very slowly. Compost delivers nutrients faster because it breaks down/decomposes faster and that's one of the reasons many prefer to use a longer lasting type mulch that doesn't need to be replaced as often. But it also tends to deliver more N compared to wood mulches as well as a broader range of trace or minor elements.

In areas where they grow well without a lot of disease issues (like in the PNW), Leylands can make an excellent screening tree, especially where they have the freedom and room to grow naturally. There is a screening row of Leylands next to me on my neighbor's property and I rather like them :-) But there's more than enough room for them to play nice. And I like sheared Leyland hedges as well, although unless you have the time and dedication to maintain them properly as needed, I wouldn't recommend them for everyone.

Leylands tend to have a bad rep because they have frequently been planted in unsuitable situations. And they do have some disease issues in certain areas. But just like any other plant, they do have their good features and serve a useful purpose if some thought and good judgement is used before siting and planting.

Sorry if you felt in any way shocked by what I posted. I may have mis-interpreted your post by thinking you had a problem with intrusive neighbours - something I have had to deal with. T.

I don't want to open a new topic but I have a question. Does anyone has some picture of a really old Leyland Cypress specimen ??? How big are the first ones? I didn't find any valuable information. THX! Zs

You have come to the wrong place wanting advice on how to force feed conifers. Leyland Cypress especially.

This rapidly-growing tree quickly outgrows its space in a typical yard unless properly and regularly trimmed. Leyland cypress only lives for twenty to twenty-five years. These trees left to grow large may have limited root support and are the first to blow down during high winds. You should consider the work needed to maintain a Leyland cypress before planting.

I would advise, if you are going to pursue this, a trip to your local nursery. I am sure they will be more then happy to sell you more then 1-2 products to promote the fast approach you are after.

My advice...leave them alone. You can shear them up to a point...15 ft then what? You should be able to enjoy them for a decade, give or take, then wind, ice storms or poor root development will eventually take them out as I noted above.

Leyland Pros:
-fuller, denser, grow fast, establish quicker.

Leyland Cons:
-deer eat them , more prone to disease (Seiridium canker), and insects (bag worms )and wind blow over.

Good luck my friend,

Dave

Leyland cypress are probably more suitable to the PNW - western WA/OR/BC in particular - than they are to much of the rest of the country. They dislike the heat and high humidity of the south and the canker and insect pests that can plague these trees in warmer summer climates tend not be an issue here. And they are not particularly short-lived here, either. I know of stands of these that are at least 30 years old and still going strong. And if one has adequate room for a grouping, it's hard to imagine them outgrowing their space - width, with sufficient allowance for it, is not the issue. Significant height over time is. But this is the land of the western red cedar and Douglas fir and large growing conifers are a dime a dozen!! Typically in smaller gardens around here, Leylands are sheared into hedges. In larger acreage - like the OP's - you will most often see them allowed to grow into natural screening, just like the WRC's and Dougs.

If with a decent root system at planting - and that is not always guaranteed depending on how they have been grown and the size at planting - they don't tend to develop any less stable a root system as other large growing conifers one finds here. Blowdowns in this area tend to be related more to saturated soil conditions in winter (when the bulk of our winds occur) or too dense a planting situation. And the conditions apply to our native conifers as well.

I think it's important not over-generalize about these trees :-) They are not the ideal choice in every situation or every location but in the OP's location and circumstances, a perfectly reasonable choice.

In the past the row along Arboretum Drive in the Seattle arboretum was being sprayed for Cypress Tip Moth. The conspicuous browning out of sections of foliage in the mass planting over the underground parking garage at the UW was said to be pathogenic.