Long narrow planters advice please

Roberts91

Hi, Excuse the bits in the floor. Complete novice gardener here with about 15m of planters to fill (about 7.5m each side of the garden). Downside is that they are only about 35-40cm wide inside. I just told our builder we wanted planters and that’s the size he built, in hindsight now I’ve started reading up on gardening we should have gone a bit wider but this is what I’m working with now! 

Can anyone help with what to plant and where? I like lavender/alliums/ lupins maybe some roses and either grasses/fern to bulk out? Our house is styled quite modern so would like to inject some colour in the garden. 

We also have a pergola for which the posts come out from the beds, what climbers would look good there?

Further to that, these beds are not yet filled. For the type of plants I’m looking at/plants you’d recommend what mix of top soil/compost would you advise? We also have a big bag of grit leftover from laying the slabs that could be used up to. 

It is a north facing garden but as it’s a long garden the flower beds are in sun the majority of the day from spring to autumn. Only in winter do they not get much if any sun

If you’re still reading thank you! X

Ladybird4

Hello Roberts91. The planter looks amazing but can you tell us if it has good drainage holes in the bottom?

Roberts91

Hi @Ladybird4 thank you! It hasn’t got a solid base, the walls are concrete blocks built on top of hardcore.

This picture shows what is at the base of them, underneath this is just a weed membrane then soil.

Ladybird4

I should have asked the depth of the planter too Roberts91 but I think that the plants you have listed should fit nicely in the planter. A clematis would grow up your pergola and if you wanted a vigorous one you could go for a Montana type.

I would be wary about the hardcore though if the planter is shallow.

Roberts91

Off the top of my head I think they are 60cm deep, someone else told me that 45cm of soil/compost would be enough so hopefully that’s right?!

We filled the first 10cm up with some leftover hardcore to save on the cost of filling them based on the above but if it has to come back out then so be it.

Ladybird4

That is a good depth Roberts91 so I wouldn't worry. You may want to think about some plants to trail over the edge of the planter such as a prostrate rosemary or campanula.

Roberts91

Oh yes that would look nice, although I think my toddler might have fun with that in reach!

For all the plants mentioned do you know what would be a good ratio of topsoil to compost to use? And grit if we can incorporate that?

Keen to get them filled and start planting, are they all ok to plant now or have I missed my spring opportunity? 

Dovefromabove

Prostrate rosemary, and possibly some trailing thymes etc over the edge won't harm your toddler, and he/she will love the scented leaves at his/her level ... great 

Ladybird4

Many plants that have been container raised can be planted at any time when the weather is suitable i.e. not frosty or snow covered so I wouldn't worry too much on that score. I would go for a 50/50 mix of topsoil and peat free compost with added grit or perlite to lighten the mix.

Lizzie27

I would not plant a clematis montana in your planter, they can grow enormous and would need lots and lots of water. Same goes for any other big plant you are thinking off. Important to do some research first.

BobTheGardener

All the plants you mention (and herbs) will do well on light soils with average nutrition, so @Ladybird4 's mix is fine.  However, if you are planting a clematis, I would incorporate a 50 litre bag of well-rotted manure from a garden centre into the soil in the area you will be planting it, as they are hungry, thirsty plants and the manure will help with both of those needs.