After staring at your pics a few times I think I've figured out what's bothering me. The garden bed sticks forward. If you need it for the size of plants in the ground it might work but if you're only going to have pots you can line the edge up with the wall of the house I think? What is the depth of the garden bed? Colour and placement of the pots. The pots look terracotta and the brickwork looks more reddish, is that right? It doesn't look like it goes together. Maybe you can use those pots somewhere else where they aren't right beside the brickwork and get some pots for that location which are either darker and match the trims of the house or are lighter and contrast with the house more. I think the pots need to somehow relate to the windows. If that room could use some privacy or shade you could put two pots in front of the windows. If you want to preserve the view out then you could put three pots against the brickwork. The mulch. It looks too low for the edging. (What is the edging?) The colour, like with the pots, doesn't look like it goes with the rest. I'd go black pebbles or something light in a similar hue to the stone foundation feature. Or maybe scoria?

Given your coastal location and aims for both coherence and low maintenance, you have a wonderful opportunity here to landscape your garden entirely with natives. As you’ve already decided to start with lillypillies (careful to avoid the variety prone to psyllid - the most resistant varieties according to Don Burke are Acmena smithii and Syzygium luehmannii: http://www.burkesbackyard.com.au/fact-sheets/in-the-garden/flowering-plants-shrubs/best-lilly-pilly-varieties/#.Vq0lfMf2PNw), I suggest you refrain from mixing in exotics to any significant degree apart from specimen pots, or other feature items. This way you have control over high maintenance species which should be nurtured for their specialness rather than a becoming a chore to avoid. I spent time visiting friends and family on the Mornington Peninsula this time last year and was shocked at the mindless distribution of what would be considered rampant bushland pests (invasive weeds) in NSW. The entire peninsula seems to boast only remnants of bushland with robust integrity. Agapanthus – because of its hardiness – has decimated vulnerable parts of the NSW bushland (especially in the Blue Mountains), requiring teams of volunteers to hack it out from rainforest and catchment areas in all weathers. Of course aggies are most romantic lining a long gravel path to a mansion, but this does not appear to be your situation here. Forgiveable in past eras, there is now no excuse for beautiful, fire-prone coastal landscapes to be placed under siege by introduced species. A substitute native I have successfully grown is Libertia, which clumps beautifully, is hardy and has a lovely little white star flower in the spring. Herewith some suggestions for conceptualizing a native garden, whose purpose, while often forgotten, is to attract birds and butterflies and to generate beauty and harmony and a sense of peace. It goes without saying that bonuses to the spiritual dimension are the disappearance of weeds and a farewell to mowing. A guiding principle in selecting natives is to select species native to your area first; information is readily available online. It’s not a hard and fast rule, but can save heartache when it comes to planting trees and shrubs that have evolved successfully in other soils and climates yet may fail in yours. Suggest a drive around the area to observe established native gardens to gain inspiration. First off (so long as not near power lines) I’d echo your coastal gums by planting an advanced specimen bang on your front right hand corner boundary, from where you might radiate a rockery. Your front garden cries out for drama, and while a rockery may be your biggest expense, one or two large feature rocks placed among an undulating design can be filled with scattered smaller rocks and a wide range of sun-loving and architectural flowering grasses (e.g. lomandras, dianellas, fescues, grass trees, kangaroo paws, etc), gorgeous flowering native plants (e.g. correas, philothecas, westringias, waratahs, proteas, etc), shrubs (e.g. acacias indigenous to the area), and groundcovers (e.g. myoporum, pratia, and brachyscome, prostrate form grevillias, the beautiful rock cover scleranthus biflorus, etc) will bring endless birds and human happiness. As for shrubs and trees, the choice is endless, thus requiring planning in consideration of the growth habit and life of a tree - which in the case of acacias, may be a mere 15 years. Decomposed granite will keep large and small landscaped areas (such as paths and rockeries) free of weed and also provides nutrients to natives (cautiously spray weeded ground with a strong solution of glyphosate before laying gravel). Be careful not to place too much soil over the tops of roots when planting, as many natives absorb phosphorus this way. Seasol is fine as a wash-through fertilizer after planting, and planting just before rain is due is another handy tip for a nitrogen fix from mother nature. Frequented by nectar-loving and berry-eating birds, the long-lived Blueberry Ash (Elaeocarus reticulatis) has to be one of the prettiest native trees of all, with its grey green foliage all year, feathery pale pink flowers in spring, and blue berries in winter. It can be hedged, but is at its best lightly pruned. It is comfortable in semi-shade, so could be planted as a feature tree out the back, but could also be a stunning success as a hedge from your garage to the letterbox. Grevillias (Mallee Dawn has soft foliage and a lovely pale orange flower) and Callistemons are relatively fast-growing once established and will quickly attract native birds (especially honey-eaters which will then gain confidence to move into other protected areas of your garden; always best to place birdbaths among shrubbery - e.g. the white-flowered Leionema – to offer little birds rapidly disappearing from the Peninsula the protection they need). Victorian Christmas Bush is a mid-height stunner and Isopogon is fabulous planted under banksias and hakeas for a bushy spot. I one saw a gnarled old banksia out front of a house that was probably the most beautiful tree I have ever clapped eyes on, perfectly pruned with its trunk formed like a bonsai writ large). A weeping acacia cognata makes a great corner feature or specimen tree, and a native hibiscus will flower profusely and gloriously in full sun. Shade at back and side cry out for more romance. You might plant native violets to run up the side under a hedge, or to fill a corner rockery out the back. Suggest plant hedges/screens and feature trees first (thus establishing your shade ‘canopy’), and construct a temporary planter box somewhere out the back where you can bring on smaller plants and shrubs while waiting to decide where to put them. The squareness of the back garden can be broken up and softened by strategically placed trees and shrubs, e.g. a large native tree in the left corner, that segues into your lillypillies, under which you could landscape a seating area. You might consider a Kennedia, Clematis aristata, or Pandorea pandorana (Wonga Wonga vine) to cover the side fence behind the garage (and definitely the back shed!). You might add two more callistemons to surround the back shed to conceal it, as well as adding variety and interest. You might infest patches of your back lawn with a native variety, such as weeping wallaby grass (e.g. Griffin). You could dig a shallow trench along the retaining wall and plant a dwarf lillypilly hedge (or substitute, like dwarf acacia cognata) along its length. One might even concede English box for the spot. Native violets/native geraniums (geranium solanderi) will both cascade over the side of any retaining wall, and will prettily flower as well given enough sun. You could plant a white hardenbergia each side of the steps (or even matching specimen eucalyptus ficilfolias!) and consider extending a simple pergola over an entertainment area that looks out over your masterpiece. Trust this inspires a little, Sandman. Keep in mind that the most interesting gardens have three layers: the canopy, the understory and the ground level shrubs, grasses, and ground covers; with the right inquiries to nurseries as to ‘microclimates’ and growth habits you will create a thing of joy – as much in the making as in completion. So far as I know the only other necessary qualification for creating a successful native garden is being a skillful pruner. Natives love to be pruned and shaped, and as long as you ‘prune to the node’, you will prevent die-back and disease, your foliage and flowering will be dense and glorious, and your garden will be the envy of the neighbourhood.

You could start off by typing "black iron beds in photos" into the search bar on this website and get some ideas from that....

The bench and either the brass 2 or 4 in black aNd brass