Hope you mean 5 inches in 5 years, what about a Swiss Stone pine of some type

If you're keeping the two taller, upright branching shrubs a weeping plant won't blend with those visually. In fact if you want any kind of dwarf or slow-growing conifer to be the featured centerpiece here it would work better to remove those two comparatively vigorous broad-leaved shrubs.

'Nana' and 'Pendula' eastern white pines are prevalent on the market but get too big for this space. However with some looking you should be able to find dwarfer forms than 'Nana', perhaps buying from a conifer specialist if you have to. Try to start out with a larger specimen so it is in scale with the existing conifers.

Picea omorika 'Pendula Bruns' or Picea glauca 'Pendula' are two nice narrow weepers that would fit the location well. Pinus strobus 'Angel Falls' would also be nice but you would need to stake it until you can stake no more.

The spruces are probably taller and narrower than is wanted.

is Niagara falls a slower version???

btw.. he didnt call for a weeper.. that was just my idea ...

ken

http://conifersociety.org/conifers/conifer/pinus/strobus/niagara-falls/

'Niagara Falls', so very nice and slower growing but it is bushier and more spreading. Most are not trained up in the US but they would still be wider spreading if they were.

I think a norrow selection of any cultivar would be a nice anchoring focal point to rise above the rest when paired with the other globose companions in the bed. Especially down the road when things start getting crowded. =)