Gardeners have been growing bulbs in pots and other containers for thousands of years. It’s a great way to:
But you can’t grow bulbs in containers the same way you do bulbs in the ground. Compared to the garden itself, even the largest containers are tiny, cramped, highly artificial worlds where the wrong potting soil, extreme temperatures, or a couple of days without water can mean the difference between success and disappointment. We hope our advice here will help, but please remember that when you grow bulbs in pots, you’re taking the place of Mother Nature, and it’s hard to do that exactly right.
On the other hand, after reviewing this page for us, our good customer and bulb-lover Elizabeth Licata of GardenRant.com offered this encouragement: “If I can do it, anyone can. I am very lazy and try to get through my gardening with as little trouble to myself as possible. So I hope your very detailed instructions don’t scare people off. ”
To bloom pots of bulbs indoors in the winter, see our “How to Force Just About Any Bulb in Pots of Soil.”
Fall-planted bulbs in containers have different needs than bulbs planted directly in the ground. If you treat them the same, you’ll probably be disappointed. If, on the other hand, you follow our advice carefully you can have beautiful pots of spring flowers welcoming friends to your front door or brightening your terrace. Please note, though, that because so much depends on your care, we don’t guarantee the success of our fall-planted bulbs when grown in containers.
1. Choose the Right Pot and Soil
When the water in soil freezes, it expands, and that can easily break terra cotta, ceramic, and even rigid plastic pots. To avoid this, plant your bulbs in flexible plastic pots — common black plastic nursery pots, for example — and then slip these pots into decorative cache-pots in spring when the bulbs start to bloom.
As for soil, even the best garden soil is usually too heavy or dense for growing bulbs in pots, and many popular potting soils will cause problems, too. Look for one that’s relatively porous and fast-draining, with a good percentage of perlite, vermiculite, or bark. Avoid mixes that are virtually all peat moss because they often stay too wet for bulbs. Avoid mushroom compost and manure, too.
2. Plant Bulbs Shallowly and Close Together
Bulbs in pots are typically planted much closer together and less deep than bulbs in the ground. (If, however, your containers are very large and more like garden beds than pots — such as in a roof-top garden — it’s best to stick to standard recommendations for depths and spacing.) Plant bulbs so they’re close but not touching, with their tips just below the soil surface. The goal is to leave as much room as possible under them for root growth. Arrange tulip bulbs with their flat side facing out for a neater display of leaves.
For a more lavish look, some experts recommend setting one layer of bulbs just above another, alternating so that bulbs are not directly on top of one another — but we say leave that to the experts. One layer of bulbs is plenty, and overcrowding can lead to problems.
Another thing we don’t recommend is combining different types of bulbs in one pot. Rooting and blooming times vary so much for different bulbs that the results are often disappointing, especially for beginners.
3. Keep Bulbs Cold But Not TOO Cold
In winter, bulbs in above-ground containers will get MUCH colder than those planted in the ground — where the earth protects them like a huge insulating blanket — and that can be deadly. Even in the coldest parts of the country, the soil a few feet below the surface rarely freezes, and a bulb planted six inches underground will enjoy relatively balmy temperatures compared to one that’s in a pot on top of the soil. Bulbs that are hardy in zone 5, for example, are hardy UNDERGROUND in zone 5, not in an above-ground container where the temperatures
Cold is essential, though! Almost all fall-planted bulbs need a certain number of hours below 48° F in order to complete the chemical changes that allow their flower stems to emerge and grow to a normal height. (This is nature’s way of preventing them from blooming during a mid-winter thaw.) The hours of “chill time” needed varies widely — tulips, for example, need a lot, while some tazetta narcissus need almost none — but if you don’t give your bulbs the cold they need, they’ll either bloom on very short stems or not at all.
Finding a spot where the temperatures are just right for your potted bulbs can be a challenge, and it all depends on how cold your part of the country gets. In some areas you can simply set them in the shade on the north side of your house, but in most places this will be either too cold or too warm. If it’s too cold, one choice is to bury the pots in the ground — maybe in your vegetable garden, for example . Put a layer of rocks under the pots for drainage, make sure the bulbs are at least as deep as they’d be if you planted them directly in the ground, and mulch with a foot or two of straw or hay. Or try them in an unheated mudroom, attic, or crawl-space, attached garage, or refrigerator (although see #5 below). If it’s too warm outside — as it may be in zone 7 and definitely in zones 8, 9, and 10 — you’ll need to “pre-chill” your potted bulbs in the refrigerator (not freezer) for 8-10 weeks either before or after planting them.
The best way to monitor temperatures in any of these places, even in the dead of night when you’re asleep, is with a maximum-minimum thermometer, available at any good garden center.
4. Protect from Freeze-Thaw Damage — and Mice, Etc.
Bulbs in pots can also be damaged by what is called the freeze-thaw cycle. Although bulbs in the ground will enjoy relatively steady temperatures, soil temperatures in containers can fluctuate dramatically from day to night. This is even more of a problem for containers in direct sun. During the day soil temperatures can skyrocket, even on a day that’s barely above freezing, thawing the soil and stimulating the bulbs to grow as if it’s spring. Then at night when air temperatures plummet, the soil in the unprotected container quickly cools and can easily freeze. This daily cycle of freezing and thawing breaks roots and weakens the bulbs. To avoid this, keep your containers in a cool SHADED spot until it’s spring and leaves have emerged an inch or more above ground.
Mice, chipmunks, and other rodents can be even more destructive. Jane Baldwin, whose tips for growing bulbs in baskets are featured below, told us that “mice and other critters were the sole cause of failure for me. I think the best solution is to either (a) store the pots in a tight closet in the garage or (b) upturn larger pots over each of them, but I’ve also stored them in old-fashioned galvanized garbage cans.”
5. Use Your Garage and Refrigerator with Caution
Most detached garages offer very little protection from the cold, but they may work for some bulbs in some zones. In other words, proceed with caution. Elizabeth Licata, who gardens in zone-6a Buffalo, NY, stores her potted bulbs in an detached garage and says, “I’ve never lost any tulips, regardless of the size of the pot or the coldness of the winter.” Hyacinths, on the other hand, haven’t done well in her garage, which makes sense because they’re less winter-hardy than tulips.
Attached garages are usually a much better place to store potted bulbs — if you keep the doors closed. The warmest areas are typically higher (heat rises) and next to the wall of the house (where heat radiates out). Unfortunately automobile exhaust fumes contain ethylene gas which can cause flower buds to abort, so if you warm up your car in the garage on cold mornings, you may end up with pots of great foliage in the spring but no flowers.
Ethylene gas is also released by ripening fruit, so if you store your bulbs in the refrigerator, seal fruit tightly in impermeable plastic bags and keep it as far away from your bulbs as possible.
6. Keep Soil Moist but Not Soggy
Since the dry peat moss in potting soil can be difficult to wet thoroughly, water your bulbs well after planting and then let the pot stand in a saucer of water for an hour or more to allow the potting soil to soak up more water. Once you’re sure the soil is wet throughout the pot, remove the pot from the saucer, allow excess water to drain out, and then return it to the empty saucer.
Use your finger to check soil moisture at least weekly throughout the winter. (Put a reminder in your phone or a note on your calendar.) Soil should be moist but never soggy. When the bulbs are just starting to grow, you’ll need to water infrequently, but later when roots fill the pot and top growth emerges, the soil will dry out much more quickly, so pay attention. Remember that a pot is a small, closed system and if your bulbs can’t get all the water they need, all the time, their growth and bloom will suffer.
If your potted bulbs are outside, you may need to protect them from getting too wet in the winter. During extended wet periods, cover the pots or move them to a sheltered spot. Bulbs that stay too wet for too long, especially tulips, will die.
Don’t water when the soil in your pots is frozen.
7. Ease into Spring
If everything has gone as planned, roots will eventually fill the pot and show at the hole(s) in the bottom. Foliage will start to emerge above the soil, and as spring approaches and temperatures rise, it will get increasingly difficult to hold this back. Once the leaves are taller than a couple of inches, move the pot gradually into brighter light and eventually full sun. Water as needed, maybe even daily once flower buds show. In the burgeoning rush of spring growth, it’s hard to overwater bulbs, although even then they never want to be water-logged.
When the buds start to open, move the pot wherever you want — and enjoy!
8. After Bloom, Compost or Replant in the Garden
When blooms fade, you can either (a) compost the bulbs, (b) replant them in the garden immediately, making sure to get their bases as deep as they would be if you had planted them there to start with, or (c) move the pot into a sunny, out-of-the-way spot (ideally buried in the ground to keep the bulbs cool) and keep them growing strongly for as long as possible. When the foliage yellows, empty the bulbs from the pots, dry completely, remove the foliage, and store in a cool, dry, well ventilated spot until it’s time to replant them in the garden in the fall. Although they may not bloom the following year, with luck and good care they’ll bounce back from their life in confinement and bloom again in future years.
When our good customer Jane Baldwin of zone-6a Moreland Hills, Ohio, found herself with surplus bulbs late one fall, she improvised an easy solution that ended up delighting her.
“A couple of years ago,” she writes, “I got caught by early snow so I planted the last of my daffodils in baskets. It looked fabulous and I highly recommend this to anyone, even if you’re not in the same predicament. In fact, it’s how I’m planting most of the daffs I ordered from you this fall.
“The baskets were just ones I found in the garage when we moved in. [If you don’t have any in your garage, thrift shops often sell them for a dollar or two.] They were nothing fancy, older and seasoned by years of
“I put them in our attached garage so they would get the necessary cold, and made sure that mice couldn’t get to them. I watered them at first but eventually the soil froze. At the end of winter when it started to thaw, I brought the baskets out on the patio to a sunny spot where they bloomed to perfection. Even though there were only 2-3 inches of soil under the bulbs and they were planted right next to each other, they performed just fine and looked exquisite in the baskets for a good long time. It was really very easy, and even our chipmunks and squirrels left them alone out there.
“At the end of spring I took the bulbs out of the baskets and kept them dry over the summer in the garage. Now they are planted on a hillside along my driveway where they continue to bloom beautifully — and every fall I plant more in baskets.”
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