Your Autumn Garden Questions Answered

Check out our answers to common autumn garden problems to help keep your garden at its best.

1. HOW CAN I ENCOURAGE MY BULBS TO FLOWER?

Q. Hi, I have been growing some bulb and tuber plants for the last few years. They shoot out at the right time of the year and grow okay, but some plants are not flowering well or at all. What can I do to make them flower? Thanks, Yukari.

A. Bulbs need plenty of sunlight, water and bulb food to thrive, so ensure they are in a sunny spot and receiving plenty of nourishment. If you are growing your bulbs in the garden feed them when planting, when stems begin to appear, when starting to flower and when dying down with Tui Bulb Food. If you are growing them in pots, you need to change the potting mix every two years and feed with Tui NovaTec Premium fertiliser. Once your bulbs have finished flowering, leave all the foliage on the plants until they die right back.

2. HOW DO I STOP THE LEAVES TURNING YELLOW ON MY MANDARIN TREE?

Q. We have recently bought a property and have a few fruit trees which is great. However the leaves are turning yellow on my mandarin tree. I have tried feeding with citrus food and worm castings, do you have any other ideas please. Thanks, Jacqualine.

A. If magnesium is deficient then the leaves will turn yellow. Your tree will benefit from a dose of Epsom salts which is magnesium. Use Tui Epsom Salts Magnesium Sulphate. Also make sure your tree is free from weeds which will compete for water and nutrients and mulch around it to help conserve soil moisture as well as keeping weeds down.

3. HOW DO I ENCOURAGE LARGER AND SWEETER FEIJOAS?

Q. I planted a feijoa tree 10 years ago. I used to get it pruned, but not for a couple of years. Last year we had a terrible crop, mostly very small fruit dropping off early. This summer I watered it like you wouldn’t believe. The fruit are much better and bigger, but not like the earlier years. How do I get this tree producing larger and sweeter fruit? Thanks, Colin.

A. We recommend feeding your feijoa tree with Tui NovaTec Premium fertiliser which is high in potassium to sweeten the fruit. As the fruit has already set you can improve the flavour now but not the size. Pruning your tree regularly once fruiting has finished will result in bigger fruit. You will get less fruit next year, but the fruit will be bigger in the long run with continued pruning.

For answers to common feijoa questions click here >

4. WHY ARE THE LEAVES ON MY RHUBARB YELLOW?

Q. Hi there, I love my rhubarb and have planted some in my garden this year. Can you please tell me why the rhubarb leaves keep turning yellow? Thanks, Pru.

A. Rhubarb likes a moist soil, rich in organic matter. It sounds like it needs a good dose of nitrogen - either blood and bone or sheep pellets. Soak some sheep pellets in a stocking in a bucket of water and use the liquid to feed your rhubarb. Tui Organic Seaweed Plant Tonic will also help and can be applied with the sheep manure liquid every seven days. Have a look and see if there are any small orange spots on the underside of the leaf, this could be rust which rhubarb is susceptible to, Seasol will also help with this.

5. WHY ARE THE ENDS OF MY COURGETTES TURNING YELLOW AND DROPPING OFF?

Q. Hi, my courgettes get to about 5cm long, start turning yellow at the end and then drop off. I feed and water them. What is causing this? Thanks, Raewyn.

A. This is blossom end rot that is usually caused by a lack of calcium and magnesium. It can also be caused by irregular watering the plant drying out and then being heavily watered. Improve air circulation around the plants, make sure watering is consistent, and add extra magnesium and calcium – we suggest Miracle Gro MaxFeed Tomato Fruit and Vegetable Food.

6. WHY DOES MY LEMON TREE HAVE PLENTY OF FRUIT BUT NO LEAVES?

Q. Hi, my lemon tree has plenty of lemons on it but no leaves. What could be causing this? Thanks, Amy.

A. Citrus are evergreen but do drop leaves, usually when they are stressed, too cold, have too much fertiliser, not enough fertiliser, if there’s frost, or they are too wet. We would suggest regular doses of Tui Organic Seaweed Plant Tonic every seven days until the tree starts bursting into leaf. Give it regular feedings in spring and summer when temperatures warm up. Don’t feed it in winter as the tree isn’t actively growing. Try adding sheep pellets to nourish the soil and mulch around the tree so it doesn’t dry out in summer. If it is in a pot and become pot bound it might need re-potting.

Search for more answers to your garden questions here >

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Your Autumn Garden Questions Answered Comments

  • What great answers to the questions asked. I learnt a lot from them. Thank you

    Beryl Palmer

  • Hi Beryl, that's great to hear! Thanks for getting in touch with this feedback. Happy autumn gardening from the Tui Team.

    jenna

  • Hi, you mentioned that a fertiliser high in potassium would sweeten feijoas. Would this be the same for cherry tomatoes and tomatoes in general.Love the question and answer column!

    Charlie

  • Hi Charlie, thanks for your feedback. Yes that's right. Tui Tomato Food www.tuigarden.co.nz/product/tui-tomato-food contains a generous amount of potassium for big juicy tomatoes :) Happy autumn gardening. Thanks, Tui Team

    jenna

  • Greetings Tui, Love your recommendations,Is there solution to scabby potatoes? Great eating but full of scabs. Regards Tony.

    Tony Robinson

  • Hi, I just wanted to make a comment about the lemon tree leaves going yellow. We noticed this last year with ours and realised that we had put the weed matting too close around the trunk. Once we cut this right back our tree has taken off, looking lovely and healthy.Thanks

    Nicole Heybourn

  • Hi Nicole, thanks for your comment. Glad to hear your lemon tree is looking healthy now :) Enjoy, Tui Team

    jenna

  • I love the question & answer column - its always so interesting & often you get solutions to problems you have yourself!

    Elaine Peckham

  • That's great to hear Elaine, glad this column helps you in your garden too! Thank you for your feedback - Tui Team

    jenna

  • I note your comment regarding the rust spots on the rhubarb and the yellowing of the leaves? Does this also relate to why my stems are always green and don't turn red at all? Would love to know the answer!

    Nadine

  • Hi Nadine, thanks for getting in touch. There are red and green varieties of rhubarb, this is normal for green varieties. Thanks, Tui Team

    jenna

  • Hi Tony, prevention is the key, as once your potatoes are covered in scab, it’s too late to treat. Future potato beds should be treated with sulphur to lower the pH. Avoid the use of fresh manure in the soil, well composted manure is fine. Practicing crop rotation on four year intervals can keep scab levels low. All the best, Tui Team.

    jenna

  • Thank you the article. If my mandarin, lemon trees (all in pots) have lots of green fruits on them is it a good time for repotting? They are either flowering or frutting all year.

    Melnikova Anna

  • Hi Melnikova, it is not ideal to move when fruit has set. If it is a matter of dropping the tree from one pot to the other without disturbing the roots you could but you will knock fruit off the tree. Wait until the bulk of the fruit has finished and then repot. If it is flowering most of the year you are going to have to sacrifice some fruit if you want to repot the plant. The best time to repot is in winter - June to August.Start feeding with Tui Organic Seaweed Plant Tonic about 4-6 weeks before repotting and this should help reduce transplant shock. All the best, Jenna ^Tui Team

    jenna

  • I’ve just transplanted a dwarf peach tree from a pot into the ground. How do I ensure it stays healthy?

    Sandy

  • Hi Sandy, dwarf fruit trees will be starting to go into dormant mode, so you will notice the leaves will begin to change colour and fall off. Suggest you spray your tree with a copper based spray as soon as the leaves fall to eliminate any fungal problems which may be lurking around and apply Tui Organic Seaweed Plant Tonic now and at least once a month for a good overall health boost. Feed in spring with Tui NovaTec Premium fertiliser. Stake the tree if it is in a windy spot. All the best, Tui Team

    jenna

  • My spring bulbs have come up already, freesia, daffodils and tulips which I only planted last month will they still flower?

    Helena van Rooy

    • Hi Helena, great question and very relevant to this autumn. It has been so unseasonably warm that the bulbs think it is time to grow! As they have come out of a chilling period before going into store, they will be fine. As temperatures cool they will stop growing and sit there until late winter/early spring. The weather is playing tricks on the garden but you will still be able to enjoy a spring show. 

      Tui Team

  • Can't find anything in questions page about taking cuttings from hydrangeas

    Kathaleen Widdowson

    • Hi Kathaleen, cuttings can be taken from hydrangeas from mid summer through to the end of autumn :) Check out the cuttings guide on our website for the steps: https://www.tuigarden.co.nz/ideas-and-inspiration/cuttings-grow-guide/

      Tui Team