Each week The West Australian’s Sabrina Hahn answers readers’ gardening dilemmas.

This week she’s sharing advice on native plants, hibiscus, screening trees and more.

To submit your own question to the Green With Envy column, published inside Saturday’s The West Australian, write to Ask Sabrina, GPO Box D162, Perth 6001, or email home@wanews.com.au.

Please include your full name and suburb. Due to the volume of questions, not all of them will be answered.

Soil solution

Q Last year I planted a “Screen Between” Pittosporum tenuifolium and this year a smaller Olearia axillaris next to my back fence to give my neighbours privacy as my lemon tree was old and had died. The brown fence gets the full afternoon sun. The plants are in dirty grey Bull Creek sand. The photos show the affected leaves on both plants. They now have new shoots in the cooler weather and seem to be growing. Is this position too hot for them and burning the leaves or do I need to add something to the soil? Can you think of a solution for this spot please?

Elizabeth Harrison, Bull Creek

A Perth’s hot and prolonged summers can be challenging for many plants, especially when they are grown in poor, hydrophobic sandy soil. A dark-coloured fence can absorb and radiate heat, increasing the temperature by several degrees. Install a shade cloth screen in front of the fence; this will drop the reflected heat given off by the fence. Additionally, improve the soil by mixing in clay and compost, and add a wetting agent every six weeks to help the soil retain more moisture. Apply Droughtshield this November to protect the leaves from excessive transpiration.

Rot riddance

Q Could you please give me some guidance on the bark conditions on our olive tree and eureka lemon tree and treatment options? I am currently treating the lemon tree for gall wasp and citrus bud mites. The change in bark on the olive started at the base and is steadily moving up and around the trunk.

Katie, Daglish

A Both trees are showing signs of sunburn that has affected the bark on their trunks. This may have been caused by collar rot in the citrus and possibly anthracnose in the olive tree. To treat the collar rot in the citrus tree, remove the bark until you reach healthy tissue, then spray the area with Yates Anti-Rot. Ensure that the trunks of both the citrus and olive trees are free of mulch. For the olive tree, apply copper oxychloride and surround the trunk with shade cloth in November.

Mystery sprout

Q Could you please identify this plant which is self-sown in a pot in my garden? Should I plant it in my garden or dispose of it? Many thanks.

Lyn King, Nedlands

A Identifying a plant by its leaves only can be quite challenging, especially in the case of smaller plants, as young leaves often differ from mature ones. I recommend repotting it into a larger pot and observing its growth over the next 12 months. If it produces flowers, identification will become much easier.

Native specialist

Q We are looking for a gardener who specialises in native gardens. Could you recommend someone?

Agnes and Marshall Fleischeuer

A There are fantastic nurseries that specialise in native plants and provide professional advice on which species will thrive in your specific soil type and aspect. Some notable nurseries include Zanthorrea, The Australian Native Nursery, APACE, Trillion Trees (open Thursday and Friday), Muchea Tree Farm, the Northern Suburbs branch of the Wildflower Society of WA, the Leschenault Community Nursery in Bunbury, and the Boyanup Botanical Nursery. The staff at these nurseries have extensive knowledge about a wide variety of species. I recommend researching at these nurseries, compiling a list of the plants you plan to use in your landscape, and then sharing this information with a landscaper or designer.

Growing fast

Q Can you please give me some advice about our hibiscus tree that’s looking a bit thin in the leaf department? It’s flowering well but is short on leaves. It’s about 18 months old and is in a north-east-facing corner.

Barrie Byers, Watermans Bay

A It is growing vigorously and needs to be planted into a larger pot; no doubt the root system has filled the pot, leaving little room for soil. It’s a great time to lightly prune and repot into a good quality potting mix with added sheep or cow manure and slow-release fertiliser. Apply Neutrog Gogo Juice after transplanting to give it a kickstart.