Peter Dowdall, Irish horticulturist and broadcaster, answers listeners' garden questions every Wednesday on C103. Here are this week's questions, with practical advice for Irish gardens in October.
Your autumn garden questions answered, from rhubarb success to crabapple problems and moving granny's rosebush.
In this week's Gardening Q&A with Patricia on C103, we chatted about some of the most common autumn garden questions, from when to prune red robin hedges and apple trees, to solving fungal problems on crabapples, moving cherished rosebushes, and what yellowing kale might be trying to tell you.
Listen back here. Press play for a clip, or open the full episode on Spotify.
October may mark the tail end of the growing season, but it's far from a quiet time in the garden. With temperatures cooling and growth slowing, it's the ideal moment to tidy, plan, and prepare your plants for winter and next year's success. If you're wondering what else to get in the ground this month, see what can I still plant in October?
When to Trim or Prune Red Robin (Photinia 'Red Robin')
If your red robin hedge was planted earlier this year, now's the time for a light tidy rather than a hard prune. When you cut back in autumn, you encourage soft new shoots, and those are easily damaged by frost.
Do this now: Give it a gentle trim to shape it.
Save this for later: Leave the hard pruning until the end of February, when the plant is still dormant but the temperatures are beginning to rise again. That way, any new growth is strong enough to cope with spring weather.
Reminder: Under Ireland's Wildlife Act, hedge cutting is not permitted from 1 March to 31 August, so late winter is your perfect pruning window. The Wildlife Act explained.
When and How to Prune Apple Trees
Jim asked the perfect question this week: when to prune apple trees, and whether frost might harm them. The simple answer: no, frost won't hurt them if you prune at the right time.
The best period for pruning apple trees in Ireland is November through January, when the tree is dormant and not putting out new growth. At that stage, the plant is "fast asleep", as I often say on air, so pruning doesn't stress it and gives cuts time to heal before spring.
Top tips:
- Remove any crossing or congested branches to improve airflow.
- Prune before bud burst (usually late March).
- Always use clean, sharp tools to prevent introducing disease.
Rhubarb: A Surprisingly Good Year
Anne from Cork mentioned her rhubarb has finally thrived after ten years of disappointment, and she's not alone! Many gardeners have noticed a stronger rhubarb crop this year, possibly thanks to more even rainfall and slightly cooler summer temperatures.
If yours hasn't done as well, feed it in early spring with a biochar plant feed such as NutriChar, well-rotted compost or farmyard manure. Avoid harvesting in its first year after division, and remember rhubarb loves rich soil and consistent moisture. There's more in my guide to growing rhubarb in Ireland.
How to Remove a Hydrangea Root
Kathleen had to cut down an overgrown hydrangea and wondered what to do about the roots. Unfortunately, there's no quick chemical fix, and I'd never recommend one.
Hydrangeas are shallow-rooted, which is good news: it's mainly a spade-and-elbow-grease job. Dig around the base, loosen the soil, and lever it out. Even large, mature plants come away more easily than you might think.
Why Is My Kale Turning Yellow?
Sean noticed his kale leaves were yellowing, and he suspected September's heavy rain might be to blame. He's probably right. Yellowing can result from either too much or too little water. In this case, saturated roots after prolonged rain are the likeliest cause.
Quick check: If the soil feels heavy and compacted, loosen it a little around the plants to let air in. Going forward, a layer of organic mulch helps regulate moisture levels and prevents both extremes.
Crabapple Trees with Brown Spots
Margaret sent photos of her crabapples covered in brown spots, a classic sign of fungal infection.
The good news? The fruit is still perfectly safe to eat or make jelly with. It just doesn't look as pretty.
Here's what to do:
- Prune in November to open up the canopy and improve air circulation.
- Avoid chemical sprays. Instead, try cultural control: healthier soil, better airflow, and clean pruning cuts.
- In early spring (March to April), drench the soil and the tree's base with a copper sulphate solution to help prevent future infections.
- Feed with a biochar-enriched fertiliser such as NutriChar to boost soil structure and plant health.
These steps make a big difference in helping the tree resist fungal problems naturally. Healthy soil is the foundation: see garden soil in Ireland.
How to Move a Cherished Rosebush
Amanda wrote about moving a rose from her late granny's garden before the house is sold, and what a lovely idea that is.
The best time to lift and replant a rose is December or January, when it's fully dormant. You'll want to dig deeply to capture the main taproot, replant it at the same soil level, and cut it back hard to make moving easier and encourage strong regrowth.
If you must move it earlier, wait until the very last moment before frost sets in. Roses are resilient, and sentimentally, it's a beautiful way to keep a piece of a loved one's garden growing.
Can I Still Trim a Beech Hedge in October?
Paul asked whether it's too late to trim the top of his young beech hedge. You're still safe: mid-October is fine for light shaping. Just avoid severe cuts once we move into November, as growth slows and the risk of frost damage increases.
Final Thoughts
Autumn gardening is all about timing: knowing when to cut back, when to hold off, and when to let nature do her thing. Even though the days are shorter, there's still plenty to do: tidying, pruning, planting spring bulbs, and preparing your garden for a vibrant spring.
Planning a bigger change to your garden?
If you are thinking of new planting, a new border or a wider redesign, tell me what you would like to do. I'll come back to you with the best next step for your garden, and what a planting plan or garden design would involve and cost.
Planning a bigger change? See my garden and planting design service.
Hear Me on Air
Tune in every Wednesday for the Gardening Q&A on C103, and catch up on past shows in my radio Q&A archive. For weekly seasonal inspiration, join me on Instagram at @the_irish_gardener.
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