Garden tips: cats, weed mats, seaweed fertiliser, flowering trees

How to protect your garden from cats and cat poo; extracting nutrients from seaweed; and other gardening tips.

Cats love catgrass (pictured), but citronella oil, vinegar, or citrus peel deter them.

I love my cat and my garden but my cat digs and scratches, using the garden as a toilet. How can I stop the cat and save the garden? - Kalar Holland, Mount Tamborine, Queensland

Spraying citronella oil or vinegar solution or laying citrus peel in affected areas is said to deter cats. Motion-activated sprinklers are useful if water restrictions are not in force. Sections of chicken wire or flyscreen mesh, pegged on top of the soil, prevent cats from scratching the earth, which is part of their toilet routine. Supply a litter tray as an alternative.

Can you recommend a weed mat for vegie gardens, or isn’t it a good idea? - Chris Hogan, Brisbane

I’m not a fan because bulbous weeds such as onion weed still grow up through weedmat, and it makes further planting and soil cultivation extremely difficult. If you have persistent bulbous weeds in the vegie patch, use layers of newspaper under the mulch to exclude light and suppress them. Wet newspaper is easy to push a trowel through for further planting and breaks down over time, which weedmat does not.

Several years ago we collected bags of seaweed, with the necessary approvals, and spread it on the garden, covering with pea straw. I heard the local beaches have piles of seaweed again. Should I remove the old residue? How does fresh seaweed compare with Seasol? - Joan Williams, by email

There are many different seaweeds but Seasol uses only brown kelp because of its valuable, growth-promoting constituents. The processing it undergoes liberates those trace elements, minerals, sugars, cytokinins and auxins for plants to take up readily. Some fresh seaweeds such as kelp, bladder weed and sea lettuce are still good sources of organic matter and nutrients, but seagrass is not and does not readily break down. You can leave the old residue in place.

What small, evergreen, flowering tree could I plant that has non-invasive roots? I’d like to train it more or less as a standard. The position has afternoon sun. We love camellias and Gordonia but they are too slow. - Joan King, Sydney.

Magnolia ‘Little Gem’ is not fast but responds very well to pruning and makes a wonderful tall standard. Also consider Michelia maudiae or M. ‘Bubbles’, which are like evergreen magnolias. Sasanqua camellias already trained as tall standards are at Camellia Grove nursery, Glenorie.

Send your questions to: [e-mail] or Helen Young, PO Box 3098, Willoughby North, NSW 2068. Website: helenyoung.com.au. The best question for November wins the indispensable new 44th edition of Yates Garden Guide ($40) plus $40 worth of Yates organic seeds and garden products.