One more thing, I have bought 3 cubic meters of Oasis sand, shall I use some of it for the lemon tree, since it likes good drainage, but I have zero knowledge about it's pH or salinity or anything else.

I don't know about the pines where you live but over here most weeds can't grow 6ft from a pine tree not to mention a citrus tree.

Pines are quite allelopathic; i.e., they tend to prevent things from growing under them.

I have wondered about planting near/under pines as well. I asked an expert once and they told me that things that like acidic soils can grow fine near pines. But it can definitely be a hostile environment to some things. Plenty of weedy things grow under our pines (I'm in NC, we have a TON of pines), so it's definitely possible for SOME things to grow. You may have to try it and see.

Over here pines (Aleppo pines) grow in alkaline soils. I don't know about allelopathic inhibition, maybe that's true, but what I know is that our pines tend to suck the soil dry as a desert, have shallow roots which makes things worse and produce very dense shade. Of course there are many kinds of pines as well as climates.

It seems like that would be a good bit close

I wouldn't plant one within 15 feet of a needle evergreen.

I grow citrus within 6ft from large Italian cypresses. They might have been better off nutrition and water wise if they were further away but they do manage to thrive and get protection from the chilly northerlies. But pines are a different thing altogether.

Don't pine trees have shallow roots? Maybe the two will be competing for root space?

The pine is only 60 cm (1.9 ft) tall, it's gonna take around 8-10 years until it becomes that tall to shed needles that can reach the desired place for the lemon, so I believe they can grow fine for about 4-5 years for sure, my concern though is to see the lemon dying after so much years and efforts, and that a lemon + pine view would be unpleasant the least.

I know citrus usually loves an acidic soil, and I know that pines' needles make the soil acidic, but I have no idea about the roots, or the nutrients, although I can fertilize, but not sure the fertilizer can hit the bottom where the roots can reach, and I see that @Denise Becker has suggested that pine trees do have shallow roots, which I don't know about either.

It's a long term project, and I want to beautify the place not destroy it, and it seems like the majority here would be for not to plant the citrus, and in that case, I might opt for a Ficus Benjamina, even if it dies that wouldn't hurt that much, this is a so much deterministic decision, so it's annoying me a lot, lol.

I would love though to see @nikthegreek 's combo if possible to share a photo of the pine and citrus next to each other, and for how many yeas they've been neighbors?

Wow! Congrats buddy, I would love to see my trees in 25 years from now, you've made me optimistic.

Whenever you can and wouldn't mind to share a pic, I would be grateful :)

Just my two cents, but I would not plant citrus close to a pine. Pines grow much faster than you think or anticipate, and their roots spread a lot. I know, mine have spread out so much they are now invading my raised veggie beds. When we reforested the two acres behind the pond, three years ago, the trees were about a foot tall. They are now over my husbands head and around six feet in circumference.

There is also half an acre in front of our house, which is supposed to be a green space, and I have planted 17 pine tree on it, and willing to plant more if God wills.

This space is 20 meters away from us, I just love the look of pines; I was between Carobs and Pines, and settled on pines, so I hope they grow as fast as yours.

As others have said, pines (depending on the type) tend to grow very fast, a 5 year old pine will likely tower over a 5 year old citrus, and at 10 years things will be much worse. Also citrus will grow in moderately acidic soil, they are not really an acid loving plant, as they prefer a soil with a pH around 6.0, compared to a true acid loving plant like blueberries that generally prefer a pH of 4.5 - 5.0

I cant understand why anybody would want pines near their house...I cant get rid of mine fast enough lol

In 10 years your pine could be 20 meters tall. As long as the sun can reach under the pine's lower branch it should do fine. Can you move the citrus tree to 4 meters distance

Ok, no citrus next to the pine then, I believe it's obvious now.

Why I would want a pine next to my house?

Hmm, I like the look, and the smell of pines, plus I have asthma and their nuts are super useful, so not sure if that's enough of a reason to plant it.

Wow! 20 meters is scary to be honest, but so far I see in my region all pines are barely 6-7 meters tall, even the ones I've grown watching and enjoying, so not sure if it's a specie, or the climate, though it's usually dry and hot here, and dry and cold in the winter.

Where are you located btw? Mexico? Is this Pinus patula we're talking about?

Also it is dubious whether pine needles do much in acidifying the soil. Even if this is true to some extend, that would only be true of acid loving pines and not of pine species growing in alkaline soil.. There are more than 100 pine species worldwide and lots of natural interspecies hybrids growing in boundary areas, so simply taking about pines creates confusion. Over here the prevailing species in the south of the country and in low altitude coastal areas is the Aleppo (Pinus halepensis).

Have to chime in about pines. Grew up in a household with 2 Eastern white pines (Pinus strobus), both about 7 years old when planted, and about 6 ft (2 meters) tall. One was planted about 10 ft (3 meters) from the house and within 10 years of planting, had to be removed for obvious reasons. The other planted around the same time was about 50 ft (15 meters) from the house but was eventually removed almost 7 years ago after it had reached over 80 ft (24 meters) tall (according to the arborist who removed it) after 40 years in the ground, and had dropped a number of large branches after a couple of severe ice/wet snow storms.

Both trees and a Norway spruce across from them, had pretty much riddled the backyard with a 20 ft (6 meter) circumference of massive surface roots around each of the trees, and all of trees literally sucked water out of the ground around them as they got older and taller (which is why the conditions under them is considered "dry shade").

However I think the idea of acid-loving plants in a pine forest can be seen in New Jersey (and other remaining pine forests along the east coast of the U.S.), where you have native blueberries and cranberries growing in the NJ "Pine Barrens", and this is due to the unique properties of sandy acid soil with perfect drainage, and a high water table (due to proximity to the ocean). The predominant pine there is apparently the "Pitch pine" (Pinus rigida), which grows in those acidic conditions.

I have seen some old posts here on DU from new property owners who discovered old citrus in the understory at the edge of woods on their property, in some cases including pines, so it's obviously not impossible but it would depend on what other conditions are present at a planting site.

I have a gorgeous azalea bush growing right at the base of one of my pines. Again, an acid-loving plant with shallow roots. Though, probably not nearly as heavy a feeder as citrus.

Pine trees are not heavy N feeders. Use a raised bed for your citrus tree to give it a head start. Four feet square 12 inches.

What type of Pine did you plant? Some are don't grow as fast as others. The ones we had planted were Loblolly, which were planted for timber. Yours may not grow as quickly. I guess one never can tell unless we do it and see. Lol.

I'm based in Algeria, so we've got a lot of the Mediterranean species, most probably the same as you in Greece.

There are giant pines forests here, however, that's in the North, and I'm in the South with a sub-saharian like climate.

I hope this would have helped a bit.

Aleppo pine should be the prevailing pine species in the North of Algeria. It is a slow growing, medium sized, drought tolerant pine which grows mainly on alkaline soils and sucks the soil dry with its extended and shallow root system. The Maritime pine may also occur. This is not dissimilar to the Aleppo. No idea what exists in subsaharan Africa.

Man! You rock!

Yes, I brought my pines from the North, all of them, and I hear the Maritime Pine name here a lot, giving it to restaurants, sport clubs, parks ...etc

It could be it indeed.

https://en.wikipedia.org/wiki/Pinus_pinaster

https://en.wikipedia.org/wiki/Pinus_halepensis