Garden tips: get rid of nutgrass, fix your lemon, make roses flower

Nutgrass is a pest in the garden but we have the answers to help you get rid of it.

Nutgrass can drive you nuts.

I have chronic nutgrass problems. The shoots are always coming up around my roses. Is there a permanent fix?

CHRIS HOGAN, BY EMAIL

Selective herbicides are sold to treat nutgrass in lawns, such as Searle’s Paspalum, Nutgrass and Clover Killer, but roses are very sensitive to them. Persistent digging by hand of the roots and bulbs is tedious but ultimately effective. An easier course is suppression, using 10 sheets of newspaper, overlapped well to cover the soil. Top with a layer of sugarcane mulch. This excludes light and gradually starves the bulbs. It’s an ongoing process.

My lemon suffers from curling leaves that copper sprays haven’t fixed. It also has puzzling lumps on the branches.

PEG ANDERSON, SUNSHINE COAST

Wind damage can cause curling leaves on citrus. Citrus leaf miner causes squiggly silvery lines and distortion on new growth. Cut off affected leaves as they contain grubs. Spray PestOil or Eco-Oil regularly during growth flushes as a preventive. Copper sprays won’t help as this is not a fungal problem. The lumps will be citrus gall wasp, a serious pest of citrus. The only control is to cut off the galls before the end of August to prevent the adults emerging and re-infesting. In some proclaimed areas control of this pest is mandatory.

My roses have no flowers. They have flowered before and get plenty of sun. I pruned them a few days ago.

RAHMAN KHAN, SYDNEY

Roses need at least six hours of direct sun a day. The major prune is in early July, when you reduce shrubs to a framework of main stems. Fertilise generously in early spring for a good flush of flowers throughout spring, using an organic-based, flower-boosting fertiliser. In late January, give roses a lighter, summer prune and feed again for autumn flowering.

My banana passionfruit vine has flowered prolifically for months but no fruit have set. Are the ants everywhere the problem?

MARIE THOMPSON, BRIBIE ISLAND

Flowers but no fruit is a pollination problem. Banana passionfruit are self-fertile so it may be lack of bees. Cool, wet and windy weather also limits pollination. Try hand pollinating using a soft paintbrush to transfer pollen between flowers. Ants are associated with sap-sucking pests; check for scale, aphids or mealybug and treat these with Eco-Oil. Control ants with Ant Sand or ant baits.