How often to water Cape leadwort

The interval

Cape leadwort is thirsty while it is settling in and sparing afterwards. Water a plant in its first year about every 10 days through the growing season when there has been no rain, and about every 30 days in winter, less for a plant in the ground. 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. Winter is the cold, short-day part of your own year, when it should be kept fairly dry. UF/IFAS says plumbago requires regular watering until established and is moderately drought tolerant afterwards.

Check the soil, not the date. Push a trowel blade or a finger 8 to 10 cm down beside the plant. If it comes out dry and crumbly, water, and if it is cool and holds together, wait. A plant in a large pot can be lifted: a dry pot is far lighter than a wet one. Pots dry faster than open ground, so a container plant needs checking more often in a hot summer.

Water from the top, slowly and deeply at the base. Let the water sink in and then leave the plant alone until the soil dries again, since a regular deep soak makes it flower more freely than light sprinkling does. NC State Extension lists sandy soil with good drainage among its conditions, and advises watering container plants sparingly in winter.

Too much water, or drainage that fails, shows as yellow leaves and a stalled plant. Too little shows as limp shoots and fewer flowers, since the plant flowers best on a deep, regular summer watering. It is drought resistant once established, so a dry spell in the ground does it little harm.

What is particular to this plant is the sap. NC State Extension rates its poison severity as medium, names plumbagin as the compound, and warns that handling can cause contact dermatitis with redness and blistering, so wear gloves when you prune it. It is also frost-tender, so a pot that is moved under cover for winter wants the least water of all.

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