How often to water New Zealand broadleaf

The interval

New Zealand broadleaf is a hedge plant, and its watering is front loaded. A hedge planted this year or last needs a deep watering about every 7 days through the growing season when there has been no rain, and an established hedge needs almost none. The Royal Horticultural Society advises watering newly planted hedges regularly for the first two years and says established hedges should not need extra water. Growing season means the warm, bright months from spring to early autumn, roughly March to September in the northern hemisphere and September to March in the southern. In winter, in either hemisphere, a dry month is the only reason to water, and the interval of 30 days is a ceiling.

Check the soil, not the date. Push a trowel blade or a finger 8 to 10 cm down beside the plant. If the soil there is dry and crumbly, water, and if it is cool and holds together, wait. A plant in a large pot can be lifted at one side, since a dry pot is far lighter than a wet one.

Water slowly and deeply at the base. Let a hose trickle for several minutes at each plant, or fill a basin of soil around the stem and let it sink in, then leave the hedge alone until the soil has dried again. A mulch of compost over the root area holds moisture in, as the RHS notes for hedges generally. Light sprinkling wets only the surface and keeps the roots shallow.

Waterlogged soil is the danger. Roots in water cannot breathe, the leaves yellow and the plant stalls, so drainage matters more than any schedule.

What is particular to this plant is that it is grown for the coast. The New Zealand Plant Conservation Network lists it as endemic, and Plants For A Future calls it very tolerant of strong maritime winds but liable to damage from cold, dry ones. Cold, drying wind browns the leaf margins of a young plant in a crisp line, and drought and waterlogging can produce a similar look, so check the soil before you decide the plant is thirsty.

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