The majority of spring-blooming bulbs, such as tulips, daffodils, and crocuses, are native to regions with harsh winters. In order for these bulbs to blossom successfully, you will need to “pre-chill” them if you live somewhere with moderate winters and little frosts (zones 8–11). The steps are listed below.
Warmer climate-adapted bulbs don’t need to be chilled first. These include Scilla peruviana, Freesia, Ranunculus, Anemone DeCaen, and Anemone St. Brigid. These winter-hardy bulbs can easily be planted in the fall for spring blossoms where they are located (zones 8–10).
The majority of bulbs that bloom in spring benefit from 10 to 14 weeks of freezing at 35 to 45F. These freezing temperatures cause a biochemical reaction in bulbs that “activates bloom production and starts root growth.” The bulbs will attempt to bloom without a cooling phase, but the flowers may be tiny and distorted. Bulbs can be pre-chilled for a longer period of time than advised, but not for any shorter period.
Start chilling the bulbs in mid- to late-October for best results, then plant them outside as soon as the chilling phase is over. As a result, the bulbs have more time to grow roots before concentrating on flowering. The bulbs will be prepared for planting in January or February if the chilling cycle is started in late fall.
As long as you don’t keep any fruit in the refrigerator while the bulbs are chilling, chilling your bulbs there is a simple choice. Ethylene gas released by ripening fruit will harm the developing blooms inside the bulbs. If you do decide to keep the bulbs in the fridge, make sure to put them in ventilated plastic bags to prevent drying out while they’re cooling.
Remove the bulbs from the refrigerator and plant them right away after they have chilled for the necessary period of time (see below). Select a planting place that will be shielded from the afternoon sun to prolong the bloom period. To assist retain moisture and keep the soil cool, you can cover the soil with a few inches of mulch after planting the bulbs.
The majority of pre-chilled bulbs will blossom 4 to 6 weeks after planting. Always treat pre-chilled bulbs like annuals.
Spring-blooming bulbs that should be pre-chilled at 35-45F
- 15 weeks Glory-of-the-Snow (Chionodoxa)
- 15 weeks for crocuses
- 12–15 weeks for hyacinths
- Muscari grape hyacinth: 12–15 weeks
- 16 weeks for daffodils
- 12–15 weeks for the Siberian squill (Scilla siberica).
- 10 to 14 weeks for tulips
- Galanthus (snowdrops): 12–15 weeks
- 13–15 weeks for iris reticulata
Do I need to keep my daffodil bulbs chilled?
Reader Trudy Stern sent me this query:
“Should I force my daffodils indoors in January or February, or should I keep them in the deep frost for a while? Tulips? Any unique advice? I am excited to enjoy some bulb beauty all winter long in my home.
I got in touch with Jeff Thompson, the horticulture director at the Buffalo and Erie County Botanical Gardens, because I believed this was a query that many readers could be interested in.
Before tulips, daffodils, and other spring bulbs bloom outdoors in Western New York, the Botanical Gardens puts on a grandiose Spring Flower Show each year. They know what they’re doing because they’ve forced hundreds of bulbs to blossom indoors for the display.
Although the bulbs require a chilly period, Thompson warned against freezing them. Place them in the fridge, not the freezer.
Put the bulbs in a top-opening opaque plastic bag, then place the bag in the crisper drawer. That will prevent your bulbs from drying out and shield them from the light that comes in through the door every time you open it.
You must have an opening in the bag so that air may circulate. According to Thompson, if the bulbs become wet, mildew and fungi may develop and cause the bulbs to die.
According to David Clark, a botanist and national garden speaker, a paper bag will also work when storing bulbs in the refrigerator this fall. However, if you have apples in your refrigerator, be careful not to store bulbs there. Ethylene gas, which is released by apples, can destroy the developing flower inside the bulb. View additional advice on how to plant spring bulbs in your garden here.
Plant the bulbs in pots, give them water, and then put the pots back in the refrigerator after the bulbs have been in there for a few weeks. While they are chilled, don’t water them once more.
“You’re attempting to deceive people into thinking they’ve experienced winter, Thompson said.
Remove the pots from the refrigerator, place them somewhere warm, provide them with light, and water them three to four weeks before you want the plants to grow and blossom.
Since November 25 some bulbs have been potted up and kept in the cooler by the Botanical Gardens personnel in anticipation of the March Spring Flower Show. The question’s author is hoping for them to blossom in January or February. You might be able to reduce your simulated winter and still obtain effects, Thompson added, if you haven’t already started chilling your bulbs.
Thompson mentioned that you might be able to find potted narcissus, hyacinths, and paperwhites right now. You don’t need to refrigerate those because the farmers have already chilled them.
Which bulbs require cooling?
Tulip planting in the spring is one of our favorite gardening rituals because it produces a stunning display of readily cut flowers for Easter, Mother’s Day, and other special occasions that call for elegant arrangements. The only spring flower that has to be chilled before growing is tulips, but there are others as well. The following is a list of every variety available at Plants for All Seasons that must chill before planting:
- Tulips
- Crocuses
- Hyacinths
- Daffodils
- Muscari
- Snowdrops
- Alliums
- Irises
- Russian Squirrel
Should bulbs be chilled before planting?
After learning more about chilling, you probably want to learn how to cool flowering bulbs. Tulips and narcissus need a 12- to 16-week cooling period before they blossom in the spring. The recommended temperature for chilling bulbs in a refrigerator is around 40 degrees Fahrenheit (4 degrees Celsius). Just be careful not to store them close to any fruit, as the ethylene gas released will lessen bloom. The bulbs should be kept in a vented mesh bag in the refrigerator.
The length of the cold period for bulbs varies depending on the species, but generally speaking, the flowers that emerge earliest, even through snow, require the least amount of chilling time, while those that do so later require the most.
Do tulip bulbs need to be chilled before planting?
In her Virginia garden, my grandma used to raise tulips. I really like them and would like to plant them in my garden, but I’ve heard Southern California doesn’t get cold enough. Ist das so?
Answer: There are two parts to the response to your query. It is true that the temperatures around here don’t drop low enough for tulips to establish a root system and return year after year like they did in your grandmother’s garden.
The key is to consider them as a “annual bulb” and pre-chill them in your refrigerator before planting. Tulip bulbs can be chilled in the refrigerator to simulate the chilly evenings of tulip-growing regions like Holland.
Tulip bulbs must be cooled. The ensuing flowers won’t be as tall and full without freezing.
Tulips rarely come back for longer than a year or two due to our warm winters. Despite the fact that some gardeners attempt to dig the bulbs up and refrigerate them, experts claim that this normally isn’t very successful.
Tulip bulbs, which ought to be showing up in nurseries, are a wonderful time to start purchasing them right now. Purchasing now ensures that you get the finest selection even though they will be available throughout the following two or three months.
Depending on the kind, tulips can bloom from March to May each spring. For the longest season of color, try planting early, mid-season, and late kinds of tulips because their bloom is famously short-lived. Tulips of the same variety planted at different periods won’t often produce a longer show because each type is bred to bloom at a given time, regardless of when it is planted.
* To keep tulip bulbs chilled for at least six weeks, put them in a paper or plastic bag that has been hole-punched. Avoid placing bulbs close to apples because they release ethylene gas, which rots bulbs.
* From late November to the beginning of January, the bulbs can be planted. Just be careful to keep them chilled until you’re ready to plant them since after they’ve been out of the cold, they tend to weaken and mold.
* Offer superb drainage. Tulips won’t survive in muddy soil. Before planting, it’s crucial to generously amend your soil with perlite or pumice and handmade or bagged compost. Gypsum is also advised if your soil is heavy clay.
* Use high-quality potting soil with plenty of perlite or pumice, or mix some into the soil to make it lighter. Tulips thrive in containers, where they frequently create gorgeous displays, and do particularly well.
Tulip bulbs should be planted in the earth 5 to 6 inches deep and 5 inches apart, pointy end facing up.
Tulips can be grown in large numbers in pots. They can be positioned in pots such that they are an inch apart and touching. Place bulbs against the pot’s edge and work your way inside in a circle until you reach the middle.
Do tulip bulbs need to be chilled before planting?
The tulip bulbs go through a procedure called prechilling, which involves keeping them between 35 and 48 degrees Fahrenheit for at least 10 weeks and no longer than 14 weeks before planting (but never in the freezer!). When you dig your bulbs after the spring bloom, it’s simple to meet the minimal requirement, but you’ll long exceed the 14-week window before you can replant the bulbs in the late fall.
There are other tricky aspects of keeping your bulbs over the summer. You shouldn’t keep the bulbs in a garage, shed, or basement without temperature control because the cooling temperature needs to be stable with no significant temperature swings.
When you’re ready to plant the bulbs, take them out of their chilly storage. Just a few hours of warming them up will return them to their original, non-chilled state.
How are daffodil bulbs pre-chilled?
In regions where the soil temperature doesn’t sufficiently cool during the winter, often USDA Zones 8, 9, and 10, spring-blooming bulbs need to be pre-cooled, or pre-chilled. Here, pre-cooling is necessary for crocuses, tulips, and hyacinths. Place bulbs in the refrigerator’s fruit and vegetable drawer for 8 to 14 weeks to pre-cool them. However, avoid storing them near ripening fruit as this can release ethylene gas, which can harm the bulbs. The bulbs should then be planted right away in the garden or in pots.
In areas with mild winters, consider bulbs that don’t require pre-cooling to avoid having to do it. These include, among others, daffodils, narcissus, iris, freesia, scilla, and triteleia. A reputable bulb catalog will specify which options need for pre-cooling and which are suitable for warm winters. Numerous bulb suppliers also provide pre-cooled bulbs; they will preserve your purchase in a cold storage facility and send it to you when planting time arrives (December or January in warm areas).
Check out our two illustrative how-to files, Gardening with Bulbs & Tubers and Bulbs.
Before planting, should bulbs be soaked?
You now understand the fundamentals, but you could still have some queries. Here are some of the questions regarding planting bulbs for spring that I am asked the most.
How deep should you plant spring bulbs?
It’s a good idea to put spring bulbs 2-3 times deeper than their height as a general rule of thumb. For the best results, however, always read the package directions.
Should you soak spring bulbs before planting?
Before planting, there is no need to soak them. However, soaking them for 12 to 24 hours can hasten the roots process if you are running late planting them.
They will root more quickly if you add fish emulsion or liquid kelp to the water before soaking.
Why are bulbs planted in the fall?
To grow and blossom, spring-blooming bulbs require a period of cold hibernation. They won’t likely blossom in the spring if they aren’t planted in the fall.
Can you plant flower bulbs in the spring?
Although it is technically possible, I don’t advise planting cold-hardy flower bulbs in the spring. If they are planted in the spring, they won’t bloom.
Additionally, there’s a chance they won’t have enough time to save the energy they’ll need to endure the winter.
Bulb planting offers such a big payoff for spring blooming. Seeing the first few green shoots pop up from the earth is so amazing. And I bet you’ll be putting more and more spring bulbs in your garden every year now that you know how simple it is.