As the name implies, hardy bulbs are those that can withstand the cold winter temperatures buried in the ground. Unlike cannas, dahlias, gladiolus and other "tender bulbs" these do not need to be dug up and stored inside during the winter months.

Selecting bulbs

a) Look for large bulbs. The larger the bulb, the more food is available to nurture developing blossoms. Larger bulbs usually cost more, but they also produce more and larger flowers. Smaller bulbs can be quite satisfactory in your garden, but below a certain size, they may not bloom the year that they are planted, though they should in future years.

Bulbs are often graded and sold by their circumference. Many hybrid daffodils, however, are graded by weight because a single bulb may actually consist of two or more bulbs united at the base, resulting in a form that cannot be measured by circumference.

b) Avoid root plate damage. Look at the bottom side of each bulb. If it is nicked or scarred, do not purchase it because root growth may be inhibited. Lily bulbs should have a few large, firm roots still attached to the basal plate.

c) Avoid moldy and shrivelled bulbs. Mold or decay indicates poor quality or disease. Shrivelling indicates water loss, which is often due to improper storage. Bulbs should normally be firm and plump.

d) Avoid soft, sour-smelling or lightweight bulbs. Occasionally, a bulb (tulip, especially) may look normal but has lost most of its weight to a fungal disease. Such bulbs will not bloom and should be avoided.

e) Buy from a reputable source. Word-of-mouth can lead you to a reliable garden center. Mail order is also a popular route. Gardening friends and neighbors can help with recommendations.

f) Buy in quantity. Often, the more bulbs you buy, the lower the price per bulb. Try ordering with a friend or several neighbors to get the quantity discount. Pre-bagged bulbs are often the best bargain as long as the bulbs inside are still in good condition.

Spring Flowering Bulbs - For the best display, large groupings of individual species of bulbs should be used. A dozen or more large flowering tulips or two dozen small bulbs such as snowdrops or crocus planted in an area will give an excellent show. It is better to group the bulbs to form a "flow" of color than to scatter individual plants around a large area. Be sure to plant varieties of differing heights such that the taller ones are to the back of the bed and the shorter stemmed plants are in front.

In mixed perennial beds, plant daffodils and other spring flowering bulbs toward the middle of the bed or the back of the border. They are the only plants in bloom at that time of the spring so, even though they may be relatively short, you do not have to plant them in the front row. Remember that the foliage of these bulbs must be left to grow until it turns brown and dies which can take until the middle of the summer. By planting the bulbs back into the bed further, other plants can emerge later in the spring and camouflage the browning foliage.

Planting depths vary depending on the size of the bulb. Generally, the bottom of the hole should be about two and one half times the diameter of the bulb. A one inch crocus corm should be placed in a 2 inch hole while a 3 inch tulip bulb needs a hole about 6 to 7 inches deep. In heavy clay soils, the bulbs should be planted a bit more shallow while in sandy soils they can be a little deeper. Bulbs planted too shallow may not survive the winter while those set too deep will be short stemmed and weak growing.

For large plantings, dig the area down to the proper depth and work some bone meal into the bottom of the excavation. For a more informal look, spread the bulbs randomly around the planting area and then adjust for proper spacing between plants. If you prefer straight rows, align the bulbs with proper spacing so that the plants can expand properly and yet fill the area with color.

On most bulbs, the roots come from a flat "basal plate" at the bottom of the bulb. When you place the bulbs, this plate should be gently pushed into the soil to assure good contact. Avoid using too much pressure or you may damage the bulb and prevent root growth.

Cover the bulbs with the soil that came from the hole and replace any mulch which was in the bed. For bulbs which are hardy for our area, you do not need to add any extra mulch.

Occasionally, squirrels will dig up bulbs or dogs will scratch away the soil in search of the bone meal. One method for preventing this is to place a layer of chicken wire a few inches above the bulbs and below the surface of the soil. This will allow the stems to emerge but will discourage the animals from digging down to the bulbs.

Summer Flowering Bulbs - The summer flowering bulbs would include hardy lilies, alliums and other plants that flower in the summer. Hardy lilies and alliums need a winter chilling so they need to be planted in the fall along with the tulips and daffodils. Occasionally, you will see lily bulbs on sale in the spring but be sure that these have been artificially chilled if you want them to bloom in the current year.

The key to remember with care of hardy bulb plants is that you are always looking forward to the next year's crop of blooms. The size and vigor of the plants you have during the current spring was all determined on how well the bulbs were filled the previous summer.

How do the plants build the bulbs to the desired size each year? Through photosynthesis, of course. For photosynthesis to take place, you MUST have green leaves. So it is imperative that you keep the leaves on the bulb plants until they naturally turn brown on their own.

Daffodils tend to be a tad more flexible and will endure some early loss of foliage and survive. However, tulips are less flexible and, if the foliage is removed too early in the season, may not be large enough to come back the next season. Or, they may only be able to produce some leaves but no flowers.

The other thing that these plants need to rebuild their bulbs is nutrients. That is where fertilizers come into play. At one time, it was thought that the time to fertilize bulbs was when they are in bloom. That is wrong.

They need the fertilizer in the ground down where the roots are as long as the foliage is still green. So, it is now recommended that you spread some fertilizer around bulb plants as soon as the foliage begins to emerge from the ground in the spring.

Remember that once the foliage is gone, the plant cannot use the fertilizer and no more growth will occur in the size of the bulb.

Perhaps the key problem with many bulbs is rot. This occurs when the bulbs are placed in poorly drained soils. In this environment, the bulbs remain wet for long periods and this encourages fungal rot organisms.

For bulbs that are truly hardy for your climate zone, there is no special winter care needed. That is the essence of the term "hardy" after all.


Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.


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