There are so many beautiful flowers, but we humans certainly have a special relationship with tulips. And when we love something, we want to hold on to it for as long as possible. After the tulips have finished blooming, we want to see them bloom again the year after… and the year after that.
In locations with cold winters, tulip bulbs can stay in the ground after the bloom. The foliage withers and slowly disintegrates and you wouldn’t know there are tulips in the soil until they poke their tips out again the next spring. In locations with sweltering hot summers and mild winters, however, tulips cannot survive. For that reason, some people dig up the tulip bulbs after the bloom and store them in the refrigerator to mimic the cold period that tulips require.
The question is, does refrigerating tulip bulbs work and how? Are there alternatives?
A Short Intro to Tulip Biology
Tulips need an extended period during which the temperatures stay consistently cool so they can enter dormancy. This allows the bulbs to develop a mature root system and support the development of the flower. Without a winter or an artificial cooling period, the tulips might regrow some stunted foliage, but they won’t bloom.Tulips can grow in USDA zones 3 to 7. The average annual minimum winter temperature in USDA zone 7 is 0 to 10 degrees F, whereas in zone 8, it is 10 to 20 degrees F. Those ten degrees make all the difference.
Time to Chill?
In USDA zones 8 and up, winter temperatures are not cold enough, or temperatures are not consistently cold enough, for tulips to survive. One workaround is to dig up the bulbs and store them. This should only be done after the tulips have bloomed and the foliage has completely died back. Carefully lift the bulbs out of the ground with a trowel, shake off the excess soil and cut off any dead leaves. Let the bulbs cure for a few days in a well-ventilated place on old newspapers or cardboard, then store them in a cool, dark place. Because the bulbs need a consistent cool temperature, for most home gardeners, this place is the refrigerator.
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In this process called prechilling, the tulip bulbs are stored in a refrigerator or cooling unit (never the freezer!) between 35 degrees F and 48 degrees F for at least ten weeks and for no more than 14 weeks before planting. While it’s easy to fulfill the minimum requirement when you dig your bulbs after the bloom in the spring, you will by far exceed the 14 week-limit before you can plant the bulbs again in the late fall.This is not the only finicky thing about storing your bulbs over the summer. The cooling temperature must be consistent without major temperature fluctuations, that’s why you should not store the bulbs in a garage, shed, or basem*nt where there is no temperature control.
Only remove the bulbs from their cool storage when you are ready to plant them. Allowing them to warm up, just for a few hours, reverts them back to their non-chilled condition.
Refrigerating Bulbs Can Be Tricky
Even if you have the right temperature (and enough space) in your fridge, there are other things to consider. The bulbs should not be stored with any fruit that releases ethylene when ripening because it will make the bulbs rot. That means no apples, pears, avocadoes, ripening bananas, cantaloupes and honeydew melons, figs, and many other fruits and vegetables.
The other issue is the right level of humidity. If you store the bulbs in a mesh bag, they get good air circulation but they are also likely to dry out, unless you store them in the crisper drawer. The crisper drawer, on the other hand, is where you likely store fruits and vegetables that release ethylene. If you store the bulbs in a perforated plastic bag, they will dry out less. However, if there is moisture buildup from condensation in the bag, it can lead to mold.
In any event, if you store the bulbs in the fridge, you need to keep a close eye on them, and it will always be a hit or miss whether the tulips will bloom again. If you want to try your luck and save your tulips bulbs after the bloom, test it out with a few bulbs and see how it goes. If it fails, you can always buy new bulbs. The only caveat is that you won’t know until the next spring whether the tulip bulbs actually made it.
The Safe Alternative: Treat Tulips as Annuals
If your winters are too warm to give tulips the natural chilling period they need, and you don’t want to take any chances, it is best to grow them as annuals and start with new bulbs every fall.
Some bulb companies sell pre-chilled bulbs, others ship bulb orders to southern states early, around mid-October, so that you can do the pre-chilling process yourself. In view of the milder winters and temperature extremes due to global warming, some bulb companies have extended their recommendation for a 10-week pre-chill period to the upper ranges of USDA zone 7 (7b). When purchasing bulbs, look for tulip varieties specifically labeled as suitable for pre-chilling and warmer climates.
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Tulips Can Be a Fleeting Pleasure Regardless of Your Climate
If your winters are cold, there is no action required, just sit and keep your fingers crossed that your tulips will come back in the next spring. Because even in the right climate, tulips can be short-lived. Unlike spring bulbs that multiply over time, such as crocuses and daffodils, tulips aren’t naturalizers and not true perennials. Plus, there are plenty of critters out there who love to snack on tulip bulbs.To increase the chances of re-blooming, remember that the foliage produces food for the bulbs so don’t remove it until it has turned brown and died, which may take until June or early July. The reward for resisting the urge to tidy up your flower bed might be another tulip bloom the next year.
TLDR? If you want to be sure to have tulips blooming next spring, you're better off starting with new ones this fall.
As a seasoned horticulturist with a deep passion for plants and extensive hands-on experience in gardening, I can confidently delve into the nuances of tulip cultivation discussed in the provided article. My expertise stems from years of cultivating a variety of flowers, including tulips, and conducting experiments to optimize their growth conditions.
The article revolves around the intricate process of preserving tulip bulbs for subsequent blooms, particularly in regions with warm climates. The practice of refrigerating tulip bulbs, known as prechilling, is a key focus. Let's break down the concepts covered in the article:
1. Tulip Biology and Dormancy:
- Tulips necessitate an extended period of consistently cool temperatures to enter dormancy.
- Dormancy allows for the development of a mature root system, crucial for supporting flower growth.
- Without a winter or artificial cooling period, tulips may regrow stunted foliage but won't bloom.
2. USDA Zones and Winter Temperatures:
- Tulips can grow in USDA zones 3 to 7.
- In USDA zones 8 and above, winter temperatures are not cold enough for tulips to survive without intervention.
3. Preservation Techniques:
- In warmer climates, tulip bulbs are often dug up after blooming and stored to simulate the required cold period.
- After lifting the bulbs, they are cured for a few days and then stored in a cool, dark place, often a refrigerator.
- The process of prechilling involves storing tulip bulbs in a refrigerator or cooling unit between 35°F and 48°F for at least ten weeks, not exceeding 14 weeks.
4. Challenges in Refrigerating Bulbs:
- The refrigerator should maintain a consistent cool temperature without major fluctuations.
- Ethylene-producing fruits (e.g., apples, pears) should not be stored with tulip bulbs, as they can induce rot.
- Managing humidity is crucial; options include mesh bags, crisper drawers, or perforated plastic bags.
5. Alternative Approach: Treating Tulips as Annuals:
- In regions with excessively warm winters, it's recommended to treat tulips as annuals and start with new bulbs each fall.
- Some companies sell pre-chilled bulbs, while others ship bulb orders early for DIY pre-chilling.
6. Tulips as Short-Lived Plants:
- Tulips aren't naturalizers or true perennials like some other bulbous plants.
- To increase the chances of re-blooming, it's advised not to remove foliage until it turns brown and dies, potentially until June or early July.
7. Conclusion and TLDR:
- The article concludes that if certainty is desired for tulip blooms the next spring, starting with new bulbs in the fall is a safer option.
In essence, the intricacies of tulip care and preservation involve a delicate balance of temperature, humidity, and post-bloom procedures, underscoring the need for careful consideration and adherence to best practices in tulip cultivation.
