11 Ranunculus Growing Secrets for Cut Flower Gardeners

When you’re planning a cutting garden, there are some flowers that you simply must grow. Of course, you want to grow things that bloom at different times of the year. It’s also important to pay attention to size, texture, color, and longevity. If a flower doesn’t have a decent vase life, it might not be worth your while. 

When it comes to looks, vase life, and just about every other important factor, there is one flower that checks all the boxes. Ranunculus is a stellar addition to the cutting garden. From its long, strong stems to its many-layered, colorful blooms, it’s ideal for use in floral arrangements.

Growing these plants can be a bit tricky. I myself had little success in my first year. But over time, I’ve learned a thing or two about coaxing these beauties to produce some of the most stunning blooms in my beds. Here are some of my secrets for growing big, beautiful, long-lasting ranunculus plants for the cutting garden.

Purchase Corms From a Reputable Source

While you can grow ranunculus plants from seeds, it’s much easier and faster to grow them from corms. These are the tiny tuberous structures that grow underground. They connect at one end and spread out at the other, like a tiny hand with outstretched fingers. 

Where you acquire your corms is an important factor in their success. Things like storage method and age will influence their success. While I would never discourage you from purchasing corms from smaller independent sellers, it’s a good idea to start small. Order a few corms from the source and see how they perform. If they work out well, that’s great! You’ve found yourself a reliable source. 

If you want to start with a large quantity of corms, I recommend going with an established retailer. Read reviews and make sure that the majority of shoppers are happy with the products they sell. Don’t let this deter you from buying from a smaller outfit, though. It’s a great idea to support small businesses. 

Plant at the Right Time For Your Region

Ranunculus plants are perennial in warm climates. In zones 8-10, you can technically leave them in the ground all year. I prefer to dig mine up in the summer, separate them, and store them until fall, but it’s not necessary if you prefer not to do this. In these warm climate zones, fall is the ideal planting time. 

Ranunculuses are surprisingly frost-tolerant. They will stay green throughout the winter even if they’re exposed to prolonged temperatures in the 20s. Below 20°F (-7°C), they may suffer. If you plant them in the fall, they will start to grow until the cold sets in. Then, they stop growing, but they don’t die back. 

When the weather starts to warm back up in late winter, your plants will begin to grow again. BY putting them in the ground early, you’ll have a head start on the season. These are cool weather lovers, so their season is short in warm climates. Planting in the fall means a much longer growing and blooming season. 

In cooler climates, like zones 2-7, these won’t survive the winter cold. You can’t leave them in the ground over the winter as you can farther south. In these zones, plant in late winter or early spring. Wait until the ground is workable and there is no more threat of a hard freeze. 

A late frost is nothing to worry about, so don’t trouble yourself by waiting until the last frost date. This will shorten your season unnecessarily. 

Soak Your Corms

Soaking is one of the most important ranunculus planting secrets. When you’re ready to get started, soak your corms before planting them. Dried and stored corms will need some hydration. This helps along the growing process and gives you a head start on the season. 

Soak your corms in warm water for three to four hours until they are plump and hydrated. Don’t overdo it; more time in the water won’t make them grow faster, but it can lead to fungal rot. 

Pre-Sprout

Immediately after soaking, you want to get those corms in some soil. Pre-sprouting is not a necessity, but it will speed up the process and protect your young plants. By doing this, you can select the healthiest plants to transplant without wasting time on those that barely sprout. 

 Fill a flat tray with high-quality seed starting mix or potting soil. Moisten the substrate slightly—it shouldn’t be soggy, just moist. Place your corms with the finger-shaped structures pointing down, then cover them with about two inches of potting mix. 

Now comes the tricky part. You’ll need to find a place to store this try that stays in the range of 40-50°F (4-10°C). This is the temperature that encourages the best root formation. If you have space in a refrigerator, this works well. An unheated garage or shed typically works, as well. Just don’t let them drop below 40°F (4°C), or they will stop developing. 

The other important factor in getting this right is light exposure. You need to keep them in the dark. Exposure to light will cause green growth, which you want to avoid so they can focus their energy on the roots. Check on them every few days to make sure they stay lightly moist. Let them grow for about two weeks. 

Transplant at the Right Time

Once your corms have developed some visible roots and the ground is workable, it’s time to transplant. Weed out any that show signs of rotting, as they will only continue to do so in the ground. 

When you transplant, avoid allowing them to warm up ahead of time. It’s best to go straight from their cool, dark, pre-sprouting space in the ground. Allowing them to warm up can cause shock, which slows growth. 

Choose the Right Location

Ranunculus plants like plenty of sunlight. When you choose a location for planting, take this into account. In warmer climates, a bit of afternoon shade can help to prolong the blooming season. In cooler climates, give them all the sun you can manage.

Another important factor in selecting a spot is drainage. Like most tubers and bulbs, these are susceptible to fungal infection and can rot easily. Because they appreciate moist soil, this is even more of a concern. To solve this issue, make sure you plant in a location with excellent drainage. 

Amend the Soil

These plants like to have plenty of nutrients available to them, so bulk up your soil with a healthy dose of organic matter. Compost, manure, and leaf mold are all great soil amendments. 

Ranunculuses also need their soil to be slightly acidic. The lower pH breaks down the nutrients they need into a form they can utilize. Adding organic material to your soil does double duty: it enriches the soil and acidifies it as well. 

Plant Right Side Up

I touched on this when we talked about pre-sprouting, but it’s an important factor, so I’ll mention it again just for good measure. Your corms have a definitive top and bottom, and the direction you plant them makes a difference. You don’t want your sprouts growing downward and trying to find their way out into the light. 

The corms consist of many small tubers, which look like small fingers, all connected in one spot. The place where they connect is the top of the corm, where the green portion of the plant will grow. When you put them in the ground, make sure that the fingers are pointing down and the connected part is facing up. 

Fertilize

These are moderate to heavy feeders, so you’ll want to fertilize them for the best and most bountiful blooms. Some gardeners like to use an organic fertilizer in addition to fish emulsion. It’s up to you to add fish emulsion, but it’s great for the soil, and you can use it as a foliar spray or soil drench.

Whether you choose to go with fish emulsion or just a conventional fertilizer, you’ll still want to fertilize every two to four weeks while they are growing and blooming. While a balanced formula will work, one that is high in phosphorus is even better. This will help build bigger, stronger buds. 

Cut Regularly

If you’re growing these in your cutting garden, chances are I don’t have to tell you to deadhead. Just make sure that you cut them often. When you do so, cut the stem all the way to the base. This helps the plant redirect energy into producing more flowers, which is the best way to prolong your blooming season.

Leave the Foliage

Finally, once your plants finish blooming, the foliage will start to fade. It’s tempting to dig them up and store them at this point, but it’s important to hold off a bit. This underrated ranunculus growing secret can make a huge difference. Here’s why: In order for your new corms to develop, they need to pull all the nutrients from the foliage back down to the roots. 

If you allow the foliage to fully die back, it gives the roots plenty of time to develop robust new corms to save for next year. I know it can be a little unsightly, but I promise, leaving them a little longer will be worthwhile next spring!