Jennifer Williams is a garden writer, consultant, and landscape designer. A former horticulture extension agent, she has bachelor’s and master’s degrees in horticulture and has gardened in numerous states across the country.

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How to Force Bulbs
by Jennifer Williams       #Bulbs   #Flowers   #How to   #Winter


Bring spring early to your home with a stunning display of spring bulbs indoors. Hint: For a longer flower show, bring bulbs out of chilling at one- or two-week intervals.

Are you looking for a way to brighten up the long winter days? Forcing spring bulbs is simple and fun and brings some color to the gray of winter. While not a very intensive activity, it does require some planning. Start by gathering the following supplies:

• Potting medium and soil scoop or small trowel
• A variety of containers
• Watering can or access to a water source
• Spring-blooming bulbs
• Metal or plastic plant labels and writing utensil
• Cold storage location and plastic bags or wrap if using a refrigerator

Step 1: Choosing Your Bulbs

For the best results, purchase high quality bulbs. Smaller bulbs will be easier for beginners. Inspect your bulbs to ensure they are dry, firm, and free of mold or decay. There are countless online suppliers that will ship bulbs out in the autumn, but my first stop is always to my local nursery to see what they have in stock. Some great choices for beginners include crocus, small daffodils, grape hyacinths, snowdrops, miniature iris, and tulips.

Step 2: Potting the Bulbs

Planting bulbs outdoors requires little effort – simply dig to the proper depth, drop the bulb in, backfill the soil, and forget about it. Forcing bulbs takes a little more precision for best results, but isn’t much more difficult.

• Begin with clean, sterile pots (a 1:10 bleach solution will clean your used pots and allow you to get more wear out of your summer annual pots). It is important to consider where you will be chilling your bulbs before choosing pots to ensure you have enough space.
• Loosely fill the container with soil with a minimum of 1 inch on the bottom, but allowing room for the bulbs (according to the chart below).
• Place bulbs into the pot as close together as you can without them touching. Do not push the bulbs down into the soil.
• Lightly fill around the bulbs with potting medium, leaving about ¼ inch from the top of the container for watering.
• Water the container until the soil is evenly moist.


For a fun twist, mix up your bulbs in the pot to create a miniature garden in a container. Make sure to pay attention to the individual planting depth requirements.

Step 3: Chilling Out

The key to success is giving your bulbs adequate time to chill in temperatures of 35-48 F (40 F is ideal). Depending on your fall and winter climate, there are several options: a north-facing shaded area outdoors will keep your bulbs cool without the sun heating containers above ambient temperatures. If outside is not an option, unheated attics, cellars, or garages will also work.

Finally, if you have some room in your refrigerator, that will keep temperatures the most stable for your bulbs. (See chart for chilling requirements.) Outdoor storage generally does not require extra watering, but those kept in covered or indoor locations need to have regular watering to keep soil moist (covering with plastic wrap or placing in a bag with vents cut will help reduce water needs).


If you are fortunate enough to have an extra refrigerator, or even an extra crisper drawer, to chill your bulbs, go for it! It will maintain the ideal temperature, but make sure to store your apples elsewhere to eliminate exposure to ethylene gas, which will spoil the bulbs.

Step 4: Forcing the Bulbs

When you have reached the required chilling time, it is time to start bringing your pots out into the sun. In the home, the ideal location is a cool spot that receives bright, indirect sunlight. It is important to transition your plants slowly by keeping their temperatures at 50-60 F for the first week. Your bulbs will begin to grow and bloom within two to three weeks.



Daffodils (Narcissus)
Tulips (Tulipa)
Crocus and grape hyacinth (Muscari)
Iris reticulate
Snowdrop (Galanthus)
Hyacinth (Hyacinthus)

Planting Depth

Half the bulb should show above the soil line
Only the tip of bulb should be above the soil line
Cover bulbs with 1 inch of soil
Cover bulbs with 1 inch of soil
Cover bulbs with 1 inch of soil
Cover bulbs with 1 inch of soil

Chill Time

12-15 wks 
10-16 wks 
8-15 wks 
13-15 wks 
15 wks 
12-15 wks 


A version of this article appeared in November/December 2016 print edition of State-by-State Gardening.
Photography courtesy of Jennifer Williams.


Posted: 11/21/16   RSS | Print


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