Wellington City Council’s Botanic Garden team members – Patrick Elliott (Curator Main Gardens), Franz Tischler (Gardener Begonia House) and Cory Meister (Gardener Main Gardens) – have pulled together some gardening tips for you to try.
There is also some tree care advice from Joshua Symes (WCC’s Team Leader Arboriculture). You can email in your horticultural questions too – see details at the bottom of this article.
Now is a good time of year to give your house plants some special care.
Pests like mealy bug (little fluffy white critters) and mites (tiny spider-looking things) can really take off in autumn. But a bit of patience and some methylated spirits will eradicate most indoor plant pests.
Dilute methylated spirits 50 per cent with water. Try using a cloth for larger areas and a small paint brush for getting right into the joins. You want to remove as many of the bugs as you can. Many of these pests are great at hiding so do a thorough check over. If you repeat this often over the next few months you can eradicate the problem and have your plants fighting fit for the next growing season.
It is a good idea to flush the soil of your pot plants every so often – this will rinse out the minerals that build up from tap water. Take the plants outside and water them three-times longer than usual. Make sure fresh water is draining right through the bottom of the pot.
Remember, your plants will need less frequent watering as the weather cools down. Water your plant deeply – until water is draining out the bottom – and always make sure your soil dries out almost completely between waterings. Too much love can be just as harmful as neglect.
Autumn is the best time of year for collecting and sowing seeds.
You should find Kowhai seeds hanging from the trees about now. Collect the brown pea-like pods and shuck out the hard yellow seeds. Put them in a bowl or cup of hot water (not boiling) and soak for 48 hours. This helps break the hard seed coat and improve germination rates.
Fill a tray or pot with 5-10cm of seed mix if you have it, otherwise potting mix will do. Lay the seeds out 1cm apart on top and cover them lightly. Place the tray in a shady, safe and sheltered spot. Germination can start after one month and will continue to germinate in flushes after that.
It can’t hurt to try growing all sorts of things from seed – gardening is all about experimentation.
Some general rules of thumb are: always remove seeds from fruit or husk before sowing if possible. Sowing depth should be relative to size (if the seed is 1cm wide it should have 1cm of mix on top of it, if a seed is 1mm you should just barely cover it).
You can also save seeds from your garden, or even from your pantry. Tomatoes, capsicum, beans, peas and pumpkins work well – just clean off all the fruit, dry out the seeds in a cool dry place, then keep them in an envelope until early spring.
If you have a weedy overgrown section, now might be the time to clear it.
One of the biggest battles for the Wellington gardener is tradescantia (Wandering Willy). It grows over everything in great dense mats, especially in moist, shady areas.
Your best bet is to rake and scrape as much of it as you possibly can into a massive pile. Don't be afraid to scrape out the top few centimetres of soil with it, because any little piece you leave behind will grow back.
Do not put tradescantia in your regular compost as it will take over that too. Cover the pile completely with a tarp or some old carpet, and weigh it down tightly, then wait. Six months should do it. Make sure it is completely dead and rotted before adding to your compost.
You will need to do regular follow-ups in the area, removing any sections that re-sprout as soon as possible. Then get planting! The best defence against weeds is a full lush garden of desirable plants.
And now for some tree advice…
Be mindful while mowing the grass around the base of your trees, especially under the drip-line. Many roots sit near the surface and often emerge above the ground. Repeated ‘scalping’ of these surface roots by lawn mowers and weed eaters can be hugely detrimental to tree health.
Putting mulch under the tree is a good option for weed prevention. It will take away the need for mowing, while also providing the tree with a valuable source of nutrients.
As well as providing substantial ecological benefits, trees can enhance our wellbeing. Studies have shown that urban areas with significant tree cover improve mental health – something to be grateful for in Wellington City where we have some fantastic urban forests.
Something to appreciate at this time of year is the dramatic changes to deciduous tree appearances. Noticing the change in leaf colour (often quite spectacular in many species) can be very rewarding.
And don’t forget about the cool wildlife you can spot on trees – including amazing native birds, stick insects, and wētā!
Send in your horticultural questions!
If you have any questions about gardening during the lockdown, email treehouse@wcc.govt.nz and our eager team of gardeners will get back to you.
If you would like a plant identified, email through some pictures, making sure to include a close-up of leaves and flowers/fruit and an overall shot of the plant or tree.
If you have a plant that is struggling, take a close-up photo of the affliction and a photo of the overall plant. Include as much information as you can about the conditions/care regime – is it dry? Is it shady? What is the soil like? How often do you water?
All horticultural questions welcome.