MARCH in the Dahlia Patch

March is one of the most beautiful months in the dahlia garden.Blooms are often at their peak, the weather is starting to soften, and there’s still time to enjoy those lush, vibrant flowers before the cool change arrives.But March is also a key month for dahlia care if you want healthy tubers and an even better show next season.

"Floralie Morello" is a prolific bloomer

Here’s what to focus on in your dahlia garden this month:

1. Keep Deadheading for Longer Flowering

Your dahlias will keep producing flowers as long as you keep cutting or deadheading!Use clean, sharp snips and remove spent blooms back to just above a pair of leaves.

Tip: Harvest flowers in the cool of the morning for longest vase life.

Deadheading not only keeps your garden looking fresh, but it signals the plant to keep blooming rather than start shutting down for winter.

2. Start Thinking About Lifting (But Not Yet!)

In most parts of the southern hemisphere, March is not quite the time to lift dahlia tubers yet — but it is the time to start planning.

If you live in an area with heavy frosts, you’ll eventually want to dig your tubers after the first true frost blackens the leaves.If you live somewhere mild (like parts of coastal NSW, Victoria, or South Australia), you might be able to leave them in the ground over winter with mulch protection.

Tip: Start collecting old newspaper, hessian bags, or breathable containers if you’ll be storing tubers soon.

3. Feed for Final Flourish

Give your dahlias a light feed in early March to help them finish strong.Use a low-nitrogen, high-potassium fertiliser (like tomato food) to encourage more blooms and stronger tubers, not leafy growth.

Avoid heavy feeding later in the month, as you want plants to start winding down naturally heading into autumn.

4. Watering Adjustments

If you're a local who does water you Dahlia's, as the days cool slightly, dahlias need less frequent watering, but still deep watering when you do.

• Check soil moisture a few centimetres down before watering.

• Avoid wetting the foliage late in the day to minimise fungal risks as humidity fluctuates.

Tip: A deep soak once or twice a week is better than a light sprinkle every day.

5. Pest and Disease Watch

March can still bring a few unwanted visitors:

• Powdery mildew (especially as humidity rises and nights cool)

• Caterpillars (especially in late summer/autumn flushes)

• Aphids loving those late blooms

  
  

Remove affected leaves, use natural pest controls where possible, and ensure good airflow around plants. Neem oil or eco-oil sprays can help if needed.

6. Start Seed Saving (Optional)

If you’re feeling adventurous, March is also a great time to save dahlia seeds!Remember: Dahlias grown from seed won’t be true to the parent plant — they’ll be new hybrids — but it’s a fun project.

• Allow a few blooms to fully mature and dry on the plant.

• Harvest the dry seed heads before autumn rain.

Tip: Label your saved seeds carefully!

Quick Summary: Your March Dahlia To-Do List

• ✂️ Keep deadheading for more blooms

• 🥀 Harvest flowers for vases

• 🧡 Light feed early in the month

• 💧 Water deeply but less often

• 🐛 Watch for mildew, aphids, caterpillars

• 🧹 Prep for tuber lifting (but wait until after frosts)

• 🌱 Save seeds if you want to experiment

March is truly a joyous time in the dahlia garden.It’s about savouring the beauty while quietly starting preparations for the end of the season.Enjoy your blooms, take lots of photos, and start dreaming about all the possibilities for next spring!

Happy gardening!