Spring flowering bulbs
Hardy spring bulbs are certainly a welcome addition to the landscape. The choice of beautiful colors is endless as breeders strive for different shades and flower varieties each year. Crocuses, daffodils, hyacinths, scylla and tulips are just a few which should not be overlooked in any garden setting. They are quite easy to work with, requiring minimal care once properly planted, and they'll reward you every spring with a wonderful show of color.
The collective term "bulb" includes different storage structures such as corms, tuberous roots, rhizomes and true bulbs. The bulbs discussed here are in the hardy bulb classification, meaning their growth cycle requires a cold period (our winter) to break their dormancy and begin spring flower development. Therefore, these bulbs are planted in the fall.
Bulbs begin to arrive in garden centers and nurseries generally at the end of August. Before purchasing your bulbs, it is important to check for any signs of disease or damage, such as cuts or bruises. The bulb should be firm, and have a protective papery skin surrounding it. Any structure which is soft or has mold growing on it should be discarded.
Once you have your bulbs, it is best to plant them as soon as possible. In our northern climate, planting time is usually from mid-September to mid-October in order for the bulb to grow roots before the ground freezes. (Tulips are one exception--you can plant these as late as you can get them into the soil.) If you received the bulbs earlier than this, store them in a dry place away from direct sunlight until you're ready to plant them.
In addition to the cold treatment bulbs receive during the winter months, they need warmth and bright light to trigger proper growth in the spring. When choosing a site, keep in mind that soil near foundations, particularly on a southern or western exposure, will warm up faster than less protected areas. In turn, bulbs planted there will flower earlier than others. Therefore, these soils should be well mulched in order to help keep soil temperatures at a more constant level. It is not necessarily an advantage to have bulbs come up too early. Cold weather may then damage them.
Try to choose locations that are sheltered from damaging winds and avoid planting in low lying areas where frost usually collects; otherwise the tender plants may be damaged early on in the developmental stages when they are just poking through the soil. Once they are further along in the flowering process, the plants are usually not affected by light to moderate frosts.
Light is another factor to consider when choosing a planting site. It is needed not only for spring growth, but also for the period after flowering when the foliage manufactures food to be stored in the bulb for the following year's growth cycle. Because much of their growth is completed before our deciduous trees and shrubs are fully leafed out, bulbs may be planted underneath or near these plants where they can create quite a nice effect, providing they do receive ample light once the flowering process is completed. The more light they receive, the better they come back each year.
Bulbs grow best in rich, well-drained soil. This is crucial for a successful planting and should not be underestimated. Avoid planting in areas that are notorious for standing water. Prepare new beds by freeing the soil of any debris such as rocks and tough matted roots. Use a garden fork or a tiller to work in some organic matter such as peat moss, fine compost or shredded leaf mulch to a depth of 10-12 inches where the bulb roots will eventually grow.
While this organic material will help amend many soil types, it is also beneficial to add some fertilizer at the same time. Work in approximately 2-3 lbs. of a 5-10-10 fertilizer per 100 square feet. For smaller areas or clump plantings, a handful of fertilizer for 10-12 bulbs should be adequate.
Till this in deeply, mixing well with the existing soil and organic matter. Never simply throw a handful of fertilizer into the hole where the bulb is to sit, as it may harm the newly forming roots and encourage bulb rot.
Decide on a design. Bulbs are much more attractive if planted in odd numbered groups or mass plantings. They may be enjoyed more also if the planting can be seen from a favorite window in the house.
The planting depth and spacing depends on the individual bulb. For specific requirements on the more common bulbs, refer to the planting chart. Generally, they are planted two and a half times deeper than their diameter. This will vary with the type of soil. With light, sandy soils, plant 1 or 2 inches deeper and on heavier clay soils, set the bulbs an inch or two more shallow. With the pointed end facing up, firmly press the bulb into the prepared soil so that the base is resting at the appropriate depth.
Once the bulbs are all placed, cover with half of the soil fill and thoroughly soak the area with water. Add the remaining soil and rake smooth to level the surface of the bed. Water the top in and mulch the surface with 3-5 inches of leaf material, grass clippings or straw. This will insulate the bulbs and help keep soil temperatures more constant during the late fall and early spring. The initial soaking should provide adequate moisture along with the normal fall rains we receive. If the precipitation is below normal during the fall season, one or two additional deep soakings may be necessary for bulbs to establish a good root system.
As soil temperatures begin warming, carefully remove the layers of mulch. Keep a bag of old mulch around in case of any hard frosts which might damage early emerging shoots.
If spring rains are sparse, water thoroughly during and after the flowering process to ensure that enough moisture is reaching the roots. But be careful not to overwater. Soggy, wet conditions will promote bulb rot.
Fertilize lightly as the flowers begin to decline, using a handful of 5-10-10 scattered throughout the clump. Make sure this is watered in well.
Cut off the faded flowers once they are finished blooming to prevent the plant's energy going towards seed production. At this time it is important to keep the foliage green and healthy as long as possible. Don't remove it until it has yellowed and withered. The longer it lasts, the better the bulbs will grow the following year.
These hardy bulbs are treated as perennials, left in the ground year after year. Every three to four years they may need to be replaced or divided if they are starting to crowd each other and aren't blooming well. If this is the case, or if you must move them for some reason, the best time is just after the foliage has yellowed and withered. Carefully lift the bulbs, shake off any loose soil and roots, discard any small ones and store the remainder in a cool, dry, well- ventilated room until fall planting time. Keep the bulbs out of direct sunlight and check them periodically for any disease. Old onion sacks or shallow seed trays work well for storing the bulbs over summer.
Bulbs generally have few insect or disease problems. Some reasons for poor flowering the first year could be the following:
- The bulbs were planted too shallow, too late in the season or were not hardy for this region.
- The bulbs were disturbed by animals such as squirrels, chipmunks, or mice.
- The bulbs rotted. Bulb rots are usually caused by using fertilizers excessively high in nitrogen or fresh manure, wet soil conditions, or by poor quality, bruised or cut bulbs.
If bulbs flowered the first year but not the second, it is quite possible the area is too shady or the foliage may have been removed before it had yellowed and withered naturally. When cutting flowers for indoor use, leave as much foliage behind as possible.
|Flower||Planting depth||Planting spacing||Flower height*|
|Early season flowering|
|Chionodoxa (glory of snow)||5 in.||3 in.||VL|
|Crocus||5 in.||3 in.||VL|
|Galanthus (snowdrops)||5 in.||3 in.||VL|
|Hyacinth||8 in.||6 in.||L|
|Muscari (grape hyacinth)||5 in.||3 in.||VL|
|Puschkinia (striped squill)||5 in.||3 in.||VL|
|Early tulips||8 in.||6 in.||L|
|Daffodil||8 in.||6 in.||MH|
|Fritillaria imperialis||8 in.||12 in.||VH|
|Mid-season tulips||8 in.||6 in.||MH|
|Late season flowering|
|Allium giganteum||8 in.||8 in.||VH|
|Scilla sibirica (Siberian squill)||5 in.||3 in.||L|
|Late tulips||8 in.||6 in.||MH/H/VH|
VL= very low (up to 6 in.)
L= low (6 in.-12 in.)
MH= medium height (12 in.-20 in.)
H= high (20 in.-28 in.)
VH= very high (over 28 in.)
H120B Reviewed 2000