Ranunculus Growing Tips

Brief Summary!

In my experience, there are 4 key things for growing  Ranunculus successfully in warm, humid climates

1.      Sufficient Airflow (from appropriate spacing)

2.      Sufficient Nutrition – they are hungry plants

3.      Preventative sprays for Powdery Mildew (every few weeks until the buds show colour)

4.      Protection from getting water on the leaves and flowers buds which leads to botrytis/grey mould (shelter)

They can quite successfully be grown in pots/crates that can be moved under cover when rain is imminent, and when flowering starts.

 

WELCOME TO THE WORLD OF RANUNCULUS!

We supply the specially bred Italian (Elegance) and French (Amandine) Ranunculus varieties, which are the tall many-petalled cut-flower varieties. It’s unlikely you will ever find these to buy in your standard garden centre. These have been grown from seed, as corms for these varieties can no longer be imported into NZ.

Our seedlings are ready to plant once you receive them. They have been given a fungal spray, and soaked in a pre-planting liquid feed containing nutrients and beneficial micro-organisms.

 

I’m not going to lie – Ranunculus are not the easiest flowers to grow in our wet humid Auckland climate. But totally possible if you give them the right conditions and some extra care. In our Auckland climate, you can expect ranunculus to flower from approx. mid August to late September (depending on which variety you have and what the weather does – they don’t flower well once the weather warms up)

Planting out your seedlings

The require a mostly sunny spot, although in warmer areas a bit of afternoon shade can be beneficial as they struggle in the heat. They are hungry plants, so loosen up the soil and add a little bit of your prefer general fertiliser when you plant. We are aiming to get as much foliage growth as possible before they start producing their flower stems. A little bit of something like Lime or Gypsum added into the soil at planting is also beneficial, as calcium helps their stems stay strong.

I have found they grow well in pots (or crates – I plant 11 in a standard bulb crate). This also means they can be moved out of the rain once they start flowering. We do not recommend growing these in little home greenhouses in the warmer parts of NZ. It simply gets too hot and the plants won’t thrive.

Spacing is crucial to achieve good airflow (important to discourage diseases), so don’t plant them too close to each other or to other plants. Somewhere between 15-20cm apart is good (15cm in cooler climates and 20cm in warmer climates)

Looking after your plants as they grow.

Ranunculus are hungry plants. Feed them with a liquid feed, preferably every 7-10 days. There are lots of different types available, but anything will do. I use a product called Nitrosol which is readily available at Mitre 10 or Yates Thrive All Purpose Plant Food Concentrate which is available from Bunnings. Just a reminder that these are concentrates so need to be diluted according to the instructions on the packet.

Keep the plants watered, but not soggy. During winter, rain will likely be enough (depending where you live). As Spring approaches and we get a few dry periods, you may need to hand water occasionally. It’s best if you water at ground level so the foliage and flowers don’t get wet, and certainly water in the morning so the plants have time to dry out in the sun.

If you have a small number of plants, I also recommend removing the oldest leaves if they start to get yellow or show any signs of disease. Dispose of these in your rubbish bin – don’t leave them on the ground next to your plants.

Diseases are the main problem with successfully growing ranunculus. They are prone to powdery mildew, and later during flowering, botrytis (grey mould). Our warm humid Spring climate in Auckland is perfect growing environment for these diseases. Don’t wait until you see signs of disease before spraying – the key is to do preventative sprays. There are many different sprays you can use (organic or synthetic), and anything will be better than nothing. If you are going to use an organic spray, then the key is to do it often (weekly). If you are using a synthetic one then probably aim to do 3 sprays before flowering. We tend to stop spraying  once the first flowers are starting to show a little colour.

There’s a couple of rose sprays that seem to work - Yates Super Sheild is a systemic fungicide and insecticide, or Combat which also includes a foliar feed.

When spraying – it’s important to get good leaf coverage (including under the leaves). If you’ve never sprayed before, then a good first sprayer for small jobs is this one https://www.mitre10.co.nz/shop/solo-professional-mini-sprayer-2-litre-white/p/136319

Protecting the plants from rain once the flower buds are showing is a good idea. A little rain is fine, but when we get days of rain and the flowers can’t dry out, the flowers quickly rot from a disease called botrytis. If you are growing in pots you can simply move them somewhere suitable once the buds appear. It’s a bit harder out in the garden, but luckily we have kiwi ingenuity!

Harvesting

If you are picking your flowers to enjoy inside, then wait until the bud feels soft like a marshmallow. They will continue to open up once they are harvested.