With the intention of writing a story about all the exciting things we can do with berms, I thought I'd better check what the official line is around berm planting. What a can of worms. The buck stops with the council and Auckland Transport, and their priority is public safety when it comes to road corridors. They have huge, thick manuals designed to guide decision-making in these areas. There are very good reasons to think before jumping in.
Auckland Council would much rather you called, lodged a request for a tree to be planted and allowed it to do it for you. There are sensitive and potentially dangerous services under our berms that you could hit when digging - at the very least it will annoy the neighbours when their broadband, gas or water no longer works, at worst you'll get "blew" eyes and a perm (an old electricians' joke). You may also find your precious plantings get dug up when the lines or pipes underneath require maintenance work.
Another safety issue is tree choice. Street trees should not be too shrubby as they block the line of sight for cars, and shrubs should be no wider or taller than 500mm. Consider the long-term maintenance of your berm. While you live at your house, you may go to the effort to plant your berm in roses or bee-friendly plants and lovingly tend them. But what about the next owner or tenant? Council then has to deal with the mess left behind.
Despite all this, I think there is plenty of berm potential out there. Here are some ideas I think could work and fit within the council and Auckland Transport requirements.
Easy care native berm
Plant native grasses (ecosourced for your area) - no need to mow these.
Maintenance: Weeding, mulching, stripping out dead foliage.
Also try: Phormium cookianum (low-growing mountain flax); Groundcovers such as Muehlenbeckia axillaris, Coprosma kirkii, Libertia(native iris), Dianella nigra (turutu)
Bee-friendly berm
Sow a wildflower or bee-friendly seed mix. Plant perennials such as rosemary and lavender.
Maintenance: Occasional weeding; allow plants to set seed in autumn, otherwise re-sow in early spring.
Edible berm
An edible berm is suitable only in quiet streets or cul de sacs with little traffic, due to pollution issues, and is not recommended by Auckland Council for health reasons. You may need to protect this one from cats and dogs, too. Plant fruit varieties with skins you can peel off. Make sure any fruit and veges are well washed before using. Plant perennial and ornamental veges such as rainbow chard, globe artichoke or kale 'Palm Tree di Toscana'. Try fruiting shrubs such as Myrtus ugni (Chilean guava) or boysenberry tied to a sturdy tripod. A permaculturalist I know grew masses of strawberries in raised planters on her berm.
If your road and berm are broad, or you live down a cul de sac with not much traffic, you should be okay to plant small, shrubby trees such as mandarin, Tahitian lime, a smaller-growing plum variety such as 'Sultan', or non-astringent persimmon. Feijoas are bushy but can be pruned to have a longer trunk to allow better visibility for cars.
Maintenance: Keep trees pruned and away from the street and footpath. Pick up fallen fruit and keep trees mulched.
Floral berm
Hardier Fijian hibiscus cultivars and species such as Hibiscus rosa sinensis are good candidates for spacious berms if they're kept pruned. If you like a meadow look, leave your grass long and plant plugs of flower species into the lawn in spring, or sow easy-to-maintain patches of wildflowers. You will need to mow the berm at the end of the season.
Things to consider
Think about the overall effect of your berm on the street. Team up with neighbours to get some cohesion and go for a best-looking street award. Check out Grey Lynn 2030's berm planting initiative at www.greylynn2030.co.nz/2013/10/02/planting-bio-corridors-on-the-berms-grass-verges/
If you're keen to beautify your street, get permission from your local council (trees) or Auckland Transport with other berm inquiries (Aucklanders).
