Iberis, the Candytuft, is a delightful cottage garden plant suitable for rock gardens, borders, bedding and the window box. I. umbellata is an annual form with flat heads of flowers in a rainbow of shades while I. sempervirens is an early flowering, white, perennial form. Full sun and good drainage are essential. Grows well in sand by the coast. The annual variety can be flowered from seed quite quickly especially if spring planted and makes a good cutflower.
Indigoffera, the False Indigo, is native to Australia as well as parts of Africa and Asia. The dainty, wistaria-like flowers weep from delicate stems and ferny foliage. Deciduous, summer and autumn flowering. Hardy, easily grown and reliable in full sun to dry, light shade in a variety of soils.
Ipomoea, includes a large family of Morning Glories some vine to 6m or more while dwarf varieties thrive in containers.
There are perennial and annual forms all enjoying sunny, hot conditions and warm (even poorer) soils that drain perfectly.
Iris are generally considered to prefer wetter sites in full sun. But in Auckland, the German Bearded Iris is excellent in dry, perfectly drained situations, even under the eaves of the house in part sun. Overwatering or overshadowing from the foliage of other plants is the biggest reason for failure.
Ixia, the African Corn Lily, is a South African favourite with thin, wiry stems laden with heavy flower clusters in spring. The grassy foliage dies away in summer. Very drought tolerant and hardy in full sun to dry, light shade. Wide colour range of cut flowers including exquisite turquoise shades.
Ixiolirion, the Tartar Lily, is another small bulb with similar grassy leaves and star-like flowers. Very hardy and drought resistant this amaryllis member is hard to find.
Jacaranda needs no introduction. This native of the high, dry deserts of Brazil flowers much better in sunny, dry years. Overwatering and feeding causes the leaves to come out first and hide the blooms. Fast, easy, effective even on the coast. Shelter from cold winds. There are red, white and pink forms!
Jasione (jae-see-oh'-nee) is a little-known meadow plant of the Mediterranean that resembles clover or scabious. The jacaranda blue flowers appear above 30cm clumps of foliage that thrives in poor, sandy, gravelly soils in a rock garden.
Junipers come in many shapes and sizes. They are prized for their hardy, easy care and ability to withstand droughts, most extremes and neglect and still look great.
Kalanchoe is best known as a container plant but will also thrive in the frost free garden for winter and spring colour.
Kniphofia, the Red Hot Poker, is as popular as it is hardy to all sorts of extremes. Divide right after flowering. Give extra water as the bud spikes begin to develop.
Kunzea ambigua, isn't the easiest to find Australian native but creates a spectacular show on coastal and well drained sites once established. Heath-like foliage frames pink, red and purple blooms resembling pohutukawa. Very drought hardy!