We have a large 'blank page' of a garden the turf is down trees in place. Now for the shrubs.... We are focussing on one particular bed which has a central part to the garden. its quite large...c15m x10m .A garden centre is coming up with a plant list for me but my query is what size of plants should I be putting in... I know it's a bit like how long is a piece of string but we want it to look a bit furnished this year and not have to wait for 5 yrs to see a result. Is this too broad a question do you think???
Ooh, how exciting! I did something similar last year, and bought a selection of different sizes. A few big shrubs (4 litre pots?), plus lots of smaller cheaper ones.
I filled in the gaps with evergreens like heucheras, with a contrasting foliage. Then ground-hugging plants such as sedums, saxifrages and creeping veronica. These spread really well to cover the bare soil, and the shrubs will eventually grow over them.
Some shrubs are naturally quicker to establish themselves than others. Buddleia, lavatera, eucalyptus will all grow quickly from the off and make your bed feel less new but can also (well should) be hard pruned every spring so can also be kept under control! Evergreens tend to be slower growing than deciduous shrubs ime (but not always - eg the eucalyptus) I know paneer said her lavatera took over but your bed sounds enormous so there should be room to accommodate it.
Bamboo is also useful for instant height but do check it is clump forming rather than spreading and even then plant it in something to restrict the roots (we used a big bin with holes made in the bottom for drainage) and give it plenty of room.
As a general rule though, most shrubs will be better in the long run the smaller they are when you put them in, so it's a balancing act.
Agree with ladymud, you can always fill in gaps with ground cover, tall growing perennials, bulbs etc. You could even stick in something like a lavatera now with a view to taking it out when everything else is better established - they aren't very long lived anyway.