You can easily brighten up your patio, deck, or window boxes in late winter and early spring with containerized bulbs. The quick growth and flower development make bulb forcing a fun and rewarding project that is great to do yourself or with kids.
Tulip and Hyacinths bulbs must first be chilled by storing them at 35-45° F, such as a refrigerator crisper drawer, for a minimum of 6 weeks and up to 14 weeks. This can be done after you have planted them in the container if space in you refrigerator allows. It's important to avoid storing bulbs near ripening fruit; the fruit gives off ethylene gas which can damage the flower inside the bulb. Once removed from cool storage, plant bulbs immediately; they may be planted anytime from November through January. Regardless of when they are planted, they will bloom in late February/March. Remember only tulips and hyacinths need to be chilled.
Steps for Forcing Bulbs Outdoors
- You will need the following materials: bulbs, soil, and a container. Almost any bulb can be grown in a container. It is common to mix several types of bulbs in the same container by layering them with the largest bulbs near the bottom and smaller ones near the top.
- Choose a container that will suit your needs; a shallower one for single flower type plantings and a deeper one for mixed type plantings. Most any container can be used as long as it has a hole for drainage. Use a potting soil that drains freely but freely absorbs moisture. We prefer to use Gardener’s Gold Potting Soil.
- Choose healthy bulbs. Avoid bulbs that are dry and withered, spongy or moldy. In general, the larger the bulb for its type, the more flowers.
- Pre-chill your bulbs if needed. (see the Special Note above)
- Moisten the soil and fill the container with at least 2 inches of potting soil and place the first layer of bulbs. Place your bulbs so that they are close together but not touching. Cover the bulbs with at least 1-2 inches of soil. If you are not layering your pot, be sure that the bulb has the appropriate amount of soil covering it. Planting depth is typically based on the size of the bulb and should be covered with a minimum of two times the height of the bulb: i.e., a 1 inch tall tulip should be covered with 2 inches of soil. If doing multiple layers, add the next layer of bulbs; place carefully so that you do not place a bulb directly above one in the lower level. Once again, cover with 1-2 inches of soil and repeat.
- Water the planted container thoroughly and set in a cool spot out of direct sun for 2-3 weeks; this will allow the bulbs to root in before the top growth begins. Move the container to a bright spot after this period. Be sure that the soil remains moist but not wet throughout the entire cycle of the pot.
- You can add additional color to the pot by over-planting the bulbs with Pansies, Isotoma, grass, Baby Tears, Primrose, and other low growing, blooming plants. When over-planting with color, place the pot directly into a brightly lit spot.
When plants are forced in this manner, they are typically treated as annuals. If you would like to get more then one season out of your container, start feeding with a water soluble fertilizer (which is formulated for bloom production) at the first sign that the bulbs have sprouted. Repeat every 2-3 weeks until the bulbs have gone dormant. Remove the spent flowers to save the plant from setting seeds and allow the foliage to die back naturally. If the foliage has not died back with in 4-6 weeks of bloom, slowly reduce the frequency of your watering until the leaves brown. Store the container in a cool, dry place. Be sure to lightly water the container about once a month; you want the soil to remain barely moist to slightly dry. Over-watering can cause rot, under-watering can cause the bulb to die.