Advice on planting trees/plants near foundation wall

stucks1234kUk4kDe · August 2020

Hello fellow gardeners,

We are looking to plant the following alongside a foundation wall in our garden

A 2 metre Blue trewithen
A 3 metre Arizona Cyprus
2 metre Oleaster/elaeagnus
1.5 to 2 metre Grisilinas
1.5 metre Photonias

Will any of these pose any significant threat to the foundation wall ?

What advice would you suggest for planting e.g. how far from the wall?

We would like them to grow to a height of approximately 2.5 /3 metres.

It's a bit of a maze on the internet and we have been given conflicting advice so hoping someone can help

Lizzie27 · August 2020

I would say most of those would be okay with the exception of the Arizona Cypress of which I know nothing, although it sounds as though it could become large!
You should plant at least half a metre away from the wall, preferably more, to keep the shrubs out of the rain shadow and away from the wall foundations.

Sorry, I should have asked first how long is the wall, what direction does it face and what is your soil type, as all these might have a bearing on what will do best in your location. Also, are you in the UK?

Obelixx · September 2020

The problem with walls is not just that plant roots can penetrate their foundations and thus weaken them over time (expensive to fix) but walls also wick a lot of moisture out of the soil and cast rain shadows so any plant can find itself struggling to get the moisture it needs to thrive.

Then you have to consider airflows. Walls don't filter wind, they funnel it and that can also be very drying so another challenge for plants.

For all these reasons you do need to answer @Lizzie27's questions about aspect and soil but also height and what lies beyond. Are you shrubs intended to soften the wall or disguise it or be a feature on their own?

Fairygirl · September 2020

No idea what a 'Blue trewithen' is [you need to give the species of plant you're asking about, not a variety, to get good advice ] or the Arizona cypress, but those are big sizes of anything to try and plant and get established. If you're in the UK, we're approaching a better time of year weather wise for that, as autumnal rains help to ease the stress. Summer is much more difficult unless you live in a cooler, damper area.

The eventual spread of those shrubs is also a factor, although Eleagnus and Griselinia are often used as hedging plants, so can be kept pruned easily enough if they get too broad.

Otherwise, as the others have said - aspect, soil and the intention for use, are all needed for good info.

Obelixx · September 2020

It's a ceanothius, I think @Fairygirl. Arizona cypress can get rather large - 40 to 50' in old money and upto 30' wide so 15m high and 8 or 9m wide.

stucks1234kUk4kDe · September 2020

How would I know/find out the type of soil we have ?

We live on a new build estate in the UK and we dont plan on letting any of the trees grow higher than 2.5-3 metres. The wall faces south east

The blue trewithen is also known as California lilaac if it helps.

The plants are designed to screen the wall/give us a bit of privacy

Thanks for all of the advice so far.

Obelixx · September 2020

You can do a squeeze test in your hand to see if you have sandy, loamy, clay etc and you can buy a soil test kit at any good garden centre and some DIYs to tell you if it's alkaline, neutral or acid.

Have a read of these links:-
identify soil types - https://www.rhs.org.uk/advice/profile?pid=179
and identify alkalinity/acidity https://www.rhs.org.uk/advice/profile?pid=239

You haven't said which way it faces not how high it is and the UK includes a wide range of climate regions which affect rain and wind levels so a general area would be helpful.

Do you know the local council regs on hedge heights? 2m is a usual limit even for mixed hedges.

Can you post a photo?

Fairygirl · September 2020

Ah - a variety of Ceanothus. They need quite dry conditions and sun to do well, and can be short lived. Photinias can be awkward in the wrong conditions too. They usually look lousy round here for instance, and don't like exposed locations much. That's why it's important to pick planting that suits your local climate and conditions.

Regardless of the choices - buying big specimens of anything isn't easy, and can be a very expensive mistake. @Obelixx is right - you need to be aware of local rules and regs re height limits to avoid any possible problems with neighbours. I'm assuming that you mean a wall on a boundary of some kind? If there are no neighbours, it's lot easier with heights.

stucks1234kUk4kDe · September 2020

Thanks everyone.

The wall 6foot high with a 6 foot fence in top of it (picture attached).

It is 14 metres in length where we plan to plant all the trees/hedge shrubs.

Behind the fence are gardens for our neighbours which are obviously on higher ground.

We live in the northern part of the south west of the UK.

Obelixx · September 2020

If that were my wall I'd attach wires at 30cm intervals along the whole length using vine eyes and proper tensioners and then I'd dig out a bed at least 2 m wide and pile on loads of well-rotted manure and plant a mix of clematis plus repeat flowering rambling roses and/or climbing roses about 50 to 60cms away from the wall and spaced according to their eventual size.

Then I'd plant small deciduous trees and a mix of evergreen and deciduous shrubs in front and spaced according to their eventual size, whether natural or pruned. Then I'd add perennials and bulbs to extend the seasons of interest and attract pollinators and birds. Finally, a good mulch to retain moisture and keep down weeds.

Dovefromabove · September 2020

I would do as @Obelixx suggests .., but I would particularly include some Alpina Clematis which flower earlier than other types to provide spring colour before the roses bloom.

They will also provide possible nest sites for small garden birds.

Advice on planting trees/plants near foundation wall

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