Bulbs tend to be hardier than other types of flowering plants and don’t need quite the same level of day-to-day care. Even so, there are a number of things you can do to help your bulbs thrive.
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How to Water Bulbs
The guidelines for watering bulbs are essentially the same as for other types of plants..
Many gardeners make the mistake of no longer watering spring-blooming bulbs after their flowers have faded away. It’s important to keep watering the bulbs even after their flowers are gone, since the bulbs use the rest of the summer to replenish their bulbs and grow stronger root systems.
How to Fertilize Bulbs
Many gardeners find that their bulbs don’t need any fertilizing at all. Over time, though, you may notice that your bulbs have begun to produce fewer or less impressive flowers. If you’ve determined that the cause is not overcrowding (which could be solved by), it might help to give your bulbs some fertilizer.
- Spring-blooming bulbs: Fertilize twice with phosphorous-heavy liquid fertilizers at half the strength indicated on the packaging. Apply the fertilizer first when the plant has established its leaves above ground, and then again after the plant has bloomed.
- Summer-blooming bulbs: Fertilize these bulbs according the same guidelines you would use to .
- Autumn-blooming bulbs: Fertilize these bulbs at the same time that you plant them. Just add a small amount of fertilizer to the hole after you plant each bulb.
How to Deadhead Plants
To ensure that your bulbs flower year after year, you want the plant to store as much energy in its bulb as possible—in other words, you don’t want the plant to waste energy producing seeds. To stop the plant from producing seeds, you can deadhead the plant—remove its spent or wilted flowers—once the blooms begin to fade.
Deadheading bulbs works just like. Using hedge clippers or your fingers, make sure to cut off not just the flower but also the bulbous swelling in the stem just behind it, which is where the seeds form.
Don’t Take Off Leaves When Deadheading
When you deadhead, take off only the flower and the swelling seed area behind it. Do not cut off the plant’s leaves, even if they’re a little faded or unattractive. The leaves are where the plant performs photosynthesis and produces the energy that will be stored in the bulb. If you take off the leaves, you cut off the flow of energy, which means that the bulb may not grow or bloom the following year.
How to Store Tender Bulbs During the Winter
If you’ve planted tender bulbs (such as cannas or dahlias) that aren’t hardy enough to survive the winter where you live, one option is treat them as annuals and just let them die. But if you don’t want to do that, you can protect your delicate bulbs from the harsh winter by digging them up and storing them in a protected place, and then replant them before the next growing season.
When to Lift Bulbs
Lifting a bulb means removing it from the ground for winter storage. For nearly all bulbs, you should lift the bulb as soon as possible after the first autumn frost. After the frost, the plant’s foliage (which will probably already appear dried and stringy) will turn black and soft.
How to Lift Bulbs
To lift a bulb, follow these instructions:
- Dig up the bulb: Using a trowel, dig very carefully around the bulb. Try to dig a hole that’s at least several inches wider than the bulb so that you don’t cut through too much of the bulb’s root system. You may also want to use the trowel or a gardening fork to loosen the soil around the bulb to make the roots easier to pull from the soil. Be very careful not to cut or mar the surface of the bulb itself in any way.
- Clean the bulb: As gently as possible, brush or shake off any loose dirt from the from the bulb and its roots. Cut away any dead shoots or leaves.
- Dry the bulb: Let the bulb dry for 2–3 days in a room inside your home, or in another dry, well-ventilated location that protects the drying bulb from direct sunlight, wind, and any other weather. Ideal temperatures for drying bulbs are 60–70°F.
- Clean the bulb again and inspect it: Once the bulb is dry, brush away any remaining dirt that you can, and inspect the bulb for insects or discolorations that may signal disease. Do not store infested or infected bulbs.
How to Store Bulbs for the Winter
Once you’ve lifted, cleaned, and dried your bulbs, you can store them for the winter.
- Prepare a storage container: A storage container should be dry and breathable. A cardboard box lined with perforated plastic wrap is a good choice.
- Put the bulbs in the container: Place the bulbs in the container and fill in around the bulbs with wood chips, vermiculite, or peat moss. Try to pack the bulbs in the container so that they don’t touch each other (including their root systems). Occasionally, individual bulbs rot over the winter—keeping the bulbs separate will make it less likely that one rotting bulb will affect the others.
- Label the containers: If you’re storing different types of bulbs for the winter, label the containers clearly so that you’ll know which is which when it comes time to replant them.
- Store the bulbs: Store the bulbs in a cool, dry place through the winter. Most bulbs store well at temperatures of 35–45°F, though some prefer warmer conditions. Check to make sure you know the temperature preferences of the bulbs you’re storing.
- Monitor the bulbs during storage: Every month or so, check the boxes to make sure the roots are neither wet nor drying out, and that none of the bulbs show any rot. If you do see rot, try to cut it away until you see clean white flesh. If the rot or other damage seems extensive, throw away the affected bulb.
- Replant the bulbs: Transplant the bulbs back into the garden about two weeks prior to the date of the last average frost for your region.
How to Pre-Chill Bulbs
Hardy, spring-blooming bulbs such as tulips require an extended period of cold during the winter in order to grow and bloom. If your region lacks such cold winters, you can still grow these bulbs by using a process called pre-chilling, in which you subject the bulbs to an artificial “winter.”
The Pre-Chilling Process
You can buy pre-chilled bulbs directly from bulb vendors, but it’s not much work just to pre-chill the bulbs yourself. To pre-chill bulbs, follow these guidelines:
- Find a cool, dry place: Bulbs must be pre-chilled for an extended period of time at a temperature that stays within a 35–45°F range, without much fluctuation. Good locations include the refrigerator (as long as it doesn’t contain apples) or an unheated basement or attic.
- Put the bulbs into storage: Store the bulbs in a breathable mesh bag, or for even better results, “plant” the bulbs in a potting mix of peat moss. Plant the bulbs so that they’re below 1″ of potting mix and the bulbs’ basal plates are facing down. Make sure the container you use has good drainage. After planting the bulbs, water the container just until you see water drip from the bottom.
- Chill for the necessary duration: Most bulbs need about 16–18 weeks of pre-chilling, though this time span can vary—so check to find out the necessary time for the bulbs that you want to pre-chill and force.
- Plant the bulbs: After the chilling period ends, you can move the bulbs to containers or plant them outdoors.
Many gardeners treat pre-chilled and forced bulbs as annuals, throwing them away after they’ve bloomed and repeating the process year after year. But if you’ve forced bulbs for indoor winter growth, and you live in a region with cold enough winters, you can transplant the bulbs into an outdoor garden after their blooms have faded and their foliage has yellowed. Keep in mind, though, that forced bulbs may take a few years to start to bloom again once they’re transplanted outside.
How to Force Bulbs
Forcing a bulb means “tricking it” into growing and flowering out of season. Gardeners usually force bulbs in order to grow potted bulbs indoors during the winter.
How to Choose Which Bulbs to Force
Not all bulbs respond well to being forced. Spring-blooming bulbs that respond well to forcing include crocuses, daffodils, hyacinths, muscari, narcissi, snowdrops, and tulips. Summer-blooming bulbs that respond well include amaryllis and paperwhites. Consult bulb catalogs to see whether a particular variety of bulb is good for forcing.
How to Force Spring-Blooming Bulbs
Forcing spring-blooming bulbs requires a period of pre-chilling and a few other steps. Forced bulbs are grown in pots, so the guidelines below explain how to plant a bulb in its pot first, and then how to pre-chill the bulb in its pot. If you don’t have space to pre-chill the bulbs in their pots, you can switch the steps and pre-chill the bulbs in a bag and then transplant them to a pot after pre-chilling.
- Buy bulbs: Forcing can take a lot out of a bulb, so only the largest, highest-quality bulbs. Order the bulbs by August to ensure that they arrive by early October.
- Prepare pots: You can use clay or plastic pots that are large enough to house 1–5 (or more) bulbs. Scrub the pots clean, then place pieces of broken crockery over the pots’ drainage holes. Fill the pot halfway with a moistened potting mixture of equal parts peat moss, potting soil, sand, and vermiculite, and stir in a teaspoon of bulb fertilizer for each quart of potting mix.
- Plant the bulbs: Place the bulbs in the potting mix, pointed ends up, and push them down a bit in the soil so that they stand upright. You can place the bulbs pretty close together, but they shouldn’t touch one another. Add enough potting mix until the tips of the bulbs are just covered.
- Water the bulbs: Water the bulbs until the potting mix is thoroughly moist but not dripping wet.
- Pre-chill the bulbs: Place the pots in a cool, dark place and for 12–18 weeks—the exact time varies based on the type of bulb and the local environment. Monitor the pots and keep the potting mix moist.
- Move the bulbs to indirect light: When a bulb has produced a shoot that reaches 2″ above the potting mix, move it out of cold storage into a place with indirect light and, if possible, temperatures that remain fairly stable between 50–59°F. Keep the potting mix moist, and turn the pots each week to keep the shoots growing straight up.
- Move the bulbs to direct sunlight: When the shoots have grown taller and the bulbs’ buds and foliage have begun to develop, move the pots into a location that has direct sunlight, such as a windowsill. This location should be slightly warmer than the previous location, but temperatures much above 65°F may actually prevent blooms from forming.
- Move the bulbs back to indirect sunlight: Once the blooms form, move the bulbs out of direct sunlight, which will maintain the flowers for as long as possible.
- Decide what to do with the bulbs after they flower: If you don’t want to plant the bulbs outside after forcing them, you can throw them away after their flowers have faded. If you do want to transplant the bulbs outside, cut away the spent blooms and move the bulbs back into direct sunlight. Do not cut back the foliage, since the leaves are vital to rebuilding the bulbs. Keep the bulbs in this location through spring and summer, and supply them with weekly or biweekly applications of bulb fertilizer at half-strength. Do not try to force the same bulbs two years in a row.
- Transplant the bulbs: Replant the bulbs in the garden in late summer or early autumn. The bulbs will revert back to their normal growing cycle. But keep in mind that forcing a bulb greatly reduces its strength, so it may take two to three years outside before it produces significant flowers.
How to Force Summer-Blooming Bulbs
Summer-blooming bulbs, such as amaryllis and paperwhites, don’t need pre-chilling. You can store these bulbs in the refrigerator until you want to force them, then:
- Plant the bulbs: Plant the bulbs in pots, following the directions given for spring-blooming bulbs.
- Give them time in the dark: Place the potted bulbs in a dark place with a stable temperature of about 65°F for three weeks.
- Move to a sunny spot: Move the bulbs into direct sunlight until they start to bloom.
- Move to indirect sunlight: Move the bulbs into a location with indirect sunlight to prolong the blooms.
- Decide what to do with the bulbs after they flower: You can discard the bulbs after they have finished flowering or provide the same care as you would to a forced spring-blooming bulb and then transplant the bulbs to the garden.