Please help me improve this 1960s designed rockery which has gaps everywhere!

L Plate Gardener

I would love some help with my garden. I have a very uphill garden with two retaining walls. One of which is connected to a very large rockery. It is unusually deep and about 20 metres long. The rockery is what you see when you look out of the living room window due to the incline so of course I want it to look nice.

I have removed some very old plants from the 1960s which were overgrown and woody. There are still more to remove probably. The overall effect is so bitty!

There are also gaps all over and I have spent over £500 in the last few days with the idea of filling them. Sadly now I have placed the pots and planted some of them, I feel defeated!!!! I cannot see how I will ever fill this space unless I spend a further £2000 or so on plants! I have thought about extending the landing strip of lawn which is between it and  the second retaining wall but of course there will be some cost to this as lots of top soil will need to be added. I am not sure if I am better investing in more plants instead!

I love alpine plants but of course they tend to be small. I also would like everygreen ones if pos so it doesn't look bare in winter. 

I have next to no gardening knowledge but have been trying to get inspiration from watching every gardening programme I can but this is overwhelming in terms of size to fill!

It is east facing so sunny but soil is very sandy

Thank you for reading my post :-) and any help would be so welcome. 

L Plate Gardener

Fritillary

From looking at your photo I can see you  have planted 3 of the same plants touching one another. If you still plant them in a group but further apart so that they are not touching then as they grow they will form a bigger clump quicker.

You will be surprised at how quickly they will grow and will soon fill the gaps. Just give them a little time.

You could also try growing some from seed. You can find  mixed packets of  seed for rockeries. Check out Chiltern Seeds.

Sussexsun

Do you have a Morrison’s supermarket nearby?
Their plants are good quality and pretty cheap.
you could get things like Arabis and pinks for a pound a pot.
if you like sedums you could buy a couple of different types from your local garden centre and divide them up to make several plants. 
The will soon grow and then you could divide again.
wilkos also sell cheap plants and bulbs. You could put in some root geranium which wilko sell for £2 a root.
go to your local garden centre regularly and keep an eye on their sin bin. The area where they put reduced plants as they are past their best but pernerials so will come back next year. Bring them home, give them a good water and feed and pop them in. Next year they will reward you for saving them.

josusa47

Many of the plants you've bought will get bigger.  Even those little alpines may spread sideways, or seed themselves.  You can sow marigold or nasturtium seeds once and their descendants will reward you unto the third and fourth generation.  On this forum, have a look at the thread called "seed and plant swap 2018" and there's also a"green plant swap" on its own website.

raisingirl

A couple of plants that spread very quickly. Erigeron karvinskianus which is not evergreen but stays green late into winter and self seeds enthusiastically. And helianthemums which are evergreen as well as having lovely bright flowers. Both are tough, spread quickly and will love that situation. Geranium Rozanne is another that is not evergreen - it starts later than other geraniums - but it flowers right through into November. It can get really big really quite quickly, mine was about 4 feet diameter in it's second year - it hasn't got too much bigger since, fortunately. 
Don't be afraid to put more upright plants in amongst the ground cover traditional rockery style - a single type of bulb growing in a small number of clumps all along the bed will tie it together visually. And don't try to cover every square inch on day 1. Mulch the ground between your plants with a compost and grit mix to replenish the nutrients and reduce weeds getting in to the gaps and to make it look tidy.
If all else fails sow some nasturtiums to give you coverage and colour (and nice edible flowers for your summer salads) for this year - they will die in the winter and make room for your perennials to grow into.

Hostafan1

I'd ask for some plants on freecycle. I've never been let down.
Lots of folk will be splitting stuff now so I'm sure someone will have something to give away, even if it's just to fill a gap until your own plants fill out.

Mary370

I think you done a good job so far. ...as stated above those little plants will grow and spread.   

Blue Onion

I would add some more rocks too.. do you have a place you could source some new ones?  Freecycle might be worth a try.  
I love the one at Wisley.  Lots of rocks.  

Borderline

I think you underestimate some of the plants' ability to grow and spread. You must at least allow one year and then decide. From the photos, it's looking rather established already. Small low growing Hebes add form and splash of colour, a variety of Erodiums and Armerias add different green tones.

hogweed

Your plants are far too close together - give them all a bit of room. I don't know what you have got in the bigger pots but would it be possible to split them into 2 or 4 and plant those up? Dwarf hebes as has been suggested, azaleas, small dwarf conifers, heathers, lots of saxifrage, sow seeds of mimulus etc. Scour seed catalogues for alpine seeds and sow these - still plenty of time for that. Chilterns do both an annual balcony mix which are all less than a foot and also a perennial alpine mix. 
Just remember that gardening is a process - we have to plan in advance and very few new plantings will come good in the first year. Look on it as a 5 year project.