The Best Way to Start Ranunculus & Anemone Corms

The Best Way to Start Ranunculus & Anemone Corms

Garden zone 3b ~ Calgary & Area

Ah, ranunculus and anemones—the showstoppers of the spring garden. With their layers of ruffled petals and their ability to make any floral arrangement look like it belongs in a European boutique, these flowers are worth every bit of effort. But let’s be honest: getting them started can be a bit like coaxing a stubborn toddler into their pj's. It takes patience, the right conditions, and maybe a bribe or two (though in this case, the bribe is a good soaking and proper temperature control). Aside from that, they are relatively easy to start, and the effort you put into them will be well worth the wait. Isn't that the case with most things?

When should you start this process and plant outdoors?

Ranunculus and anemones are hardy annuals in our area (zone 3b), meaning they thrive in the cooler conditions of spring. Once the heat of summer comes, you'll notice that the blooms rapidly decrease and will eventually stop all together. That is the case for field grown ranunculus, however, in pots on my front steps, I have had great success with blooms going throughout the summer. This is unusual, but maybe they just really love my porch!

Being a hardy plant, they are resilient to LIGHT frost, and you can generally plant them out 4-6 weeks before your last frost date, or as soon as you can work your soil. In my area we have a weather anomaly called "Chinooks" that like to play tricks in the gardener's mind. Chinooks bring a deceptive false sense of spring. They come and melt away our snow, and if around for too long, they warm up the frost layer of soil just enough to be "workable", and you see some premature sprouts here and there in your garden (It's March 13 and I've already noticed some intrepid weeds making their way in my beds). Please use "workable soil" as a loose rule and keep note of your forecasts. Too early planting can result in garden devastation, but you might just need to experience this yourself (insert me, I'm that type of learner or I used to be anyway!) Every year in the garden is a journey and learning experience. That's just part of the process, yes, even the frustrating experiences add to your overall success. Take good notes of when you're planting, conditions etc to use for future planning. It is worth the time, and will help you out next year.

Here in Calgary, we can have a sunny 10°C day followed by snow and -5°C in the evening. Any weather is fair game apparently in Alberta, after all, variety is the spice of life. In summary of that rant: the safe bet for the home gardener is planting out 4-6 weeks before last frost. Ranunculus generally take 90 days to produce blooms, so you'll need to do some math to reverse engineer your start dates for May/June blooms.

As mentioned, you'll want to keep an eye on your temperatures and I would suggest covering them at night if overnight lows dip, or frost is expected. We plant ours under low tunnels, nestled under frost cloth to get a jump on the short spring season.

What comes next? Great question! If you're ready to transform those shrivelled little octopi into your garden’s headliner, pay attention.

Step 1: Wake Them Up With a Soak

Straight from the bag, ranunculus and anemone corms look like something you might find at the bottom of a forgotten drawer—dry, shrivelled, and slightly suspicious. Don't be alarmed, consider this a good time to reflect on how easy it is to judge a book by its cover, and just why you shouldn't. For field farming, we need to keep our colours separate, so we use mesh bags to keep each variety together (some wholesalers will send your supply nicely pre-packed in them). If purchasing corms from your local garden centre they generally come in perforated plastic bags. You'll need to take them out and put them into a container. I use my handy grocery tote to have all of the corms soaking all at once, saving on time and water. Simply fill the container with room temperature water and make sure all of the corms are submerged. If you want to get fancy and use a mesh bag, make sure to get a large one because the corms will easily double or triple in size as they plump up. (Think of it as a spa day before they get to work.) If you're only sprouting a few corms, you can use an ice cream pail or any container of your choosing and let them 'free soak', omitting the bag altogether.

Ranunculus and Anemone corms are EXTREMELY temperamental when it comes to bacteria and are very, VERY susceptible to mould and rot. You absolutely need to make sure that you're properly oxygenating the water. Don't skip this step! You can do this easily at home in three different ways.

  1. Putting your bucket under a slow steady trickle of water where you see some bubbles happen.
  2. Set a timer and commit to changing the water every 30 mins. 
  3. Use an aquarium air pump.
I prefer the latter because it reduces water wastage and you can get on with other things during the wait. Let your corms soak for 3.5 hours while you cozy up with your favourite book. Don't let them soak longer though, because you don't want to promote rotting in the legs. Sneaky rot, it will ruin everything!

Lastly, remove the corms from your bucket and rinse. Mix up an anti-fungal solution of 1/4 cup apple cider vinegar into 3 litres of water and soak your corms for the remaining 30mins. Drain well.

Step 2: Pre-Sprouting for a Head Start

Now, you could plant them directly in the soil after soaking, but if you want to be a true overachiever (and get earlier blooms), pre-sprouting is the way to go.
  1. Fill a 1020 tray halfway with damp potting mix or vermiculite—moist but not sopping wet. I use vermiculite because I have found it to be the most successful way to avoid mouldy corms.. If you’re only sprouting a few, you can skip vermiculite because it can be silly expensive. It’s useful if you're buying in bulk and have a use for an extra 113 litres.
  2. Nestle the corms into the tray in nice neat rows, pointy sides (legs) down, making sure they have breathing room. Did I mention rot? Mould? Alas, no touching, closely spaced to maximize your planting area, but no legs touching. Cover trays with the remaining dampened vermiculite.
  3. Tuck them away in a cool, dark place (around 10°C) for 10 to 14 days. MAKE SURE YOU LABEL THEM, I suppose that only really matters if you're planting in bulk or if you have the memory of a goldfish. Try as I may with the best intentions to remember which row was planted with what colour, it never happens. Even with the best intentions, your labels can fall off or be washed away (talk about an organization nightmare!) I've been there, and likely will be there again at some point.
  4. Don't be an anxious parent and check on them twice a day. It's not needed. You do want to make sure that your vermiculite or other medium is not too dry, I use a mist sprayer to lightly dampen the tops of the trays every few days. The corms are very similar to Goldilocks and the three bears: not too wet, not too dry, they need to be just right. If they’re starting to grow little roots, you’re on the right track! Once the shoots emerge they will look pale and white. Have no fear, you haven't done anything wrong, this is normal. Pop them under your grow lights and the light will green them up. Continue to lightly mist until planting out. The little darlings really do not want your water.

Step 3: Planting Time

Once they’ve developed roots and a little sprout on top, it’s go-time! If you skipped pre-sprouting, no worries—just plant those soaked corms directly in the soil. If you don't have the right weather for planting out, you can pot them into larger trays or pots to continue growing until your garden is ready for them. If you do this and the foliage gets too big, you'll need to harden them off in stages before planting out.

Planting depth & spacing:

  • Ranunculus: Pointy-side down (it should be pretty obvious at this point if you have green sprouts on the top), 2 inches deep, as close together as 6 inches apart.
  • Anemones: Any side up (they’re less picky), 1-2 inches deep, 4-6 inches apart.
They love well-drained soil and full sun, so pick a spot where they won’t have wet feet. Nobody likes soggy socks, not even flowers. Additionally, I mulch each of our rows with wood shavings from my local UFA feed store (I'm sure any pet store would have them). Mulching with this type of shavings will help keep the soil cooler and weeds at bay. Water sparingly until well established.

Step 4: Enjoy the Show!

After about 90 days, you’ll be rewarded with blooms that look too perfect to be real. Cut them often to encourage more flowers, and use them in arrangements as they have a terrific vase life of 10-14 days.

So there you have it! The best (in my opinion) method for starting and growing ranunculus and anemones. A little prep work, a lot of patience, and a dash of garden magic, and you’ll have the kind of spring display that makes you stop and sigh in admiration.

Happy growing!
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