MARSHALL'S ANSWERS TO FAQS ON BULBS
Q. Why do bulbs often look so different?
A. Bulbs are like other creatures; they vary from genus to genus and species to species. But some "bulbs" look very different from others because they really aren't bulbs at all.
Q. What is a bulb?
A. A bulb is a flattened or compressed stem called a basal plate, usually growing underground, with a growing point on top and surrounded by enlarged, fleshy scales or layers that store food. The layers or scales are the bases of leaves. Roots grow downward from the basal plate. Root scars or dried roots may persist on the bottom of the basal plate. Bulbs may or may not be covered with papery structures called tunics. Tunics help to protect bulbs from drying out. The onion is a good example. Some bulbs do not have tunics. The Easter lily is a good example. Bulbs without tunics lack protection from drying out, so special care must be taken to keep them moist until they are planted.
Q. What are some examples of bulbs?
A. Examples of bulbs include allium (onion), lilium, narcissus, tulip and hippeastrum.
Q. What is a corm?
A. A corm is an enlarged, solid stem, usually growing underground, with a basal plate on the bottom and a growing point on top. This top growing point is called a terminal bud. The stem is divided into sections. The sections are separated by structures called nodes. Other growing points called lateral buds can arise from the nodes along the sides of the corm. If the main growing point is damaged, the lateral buds can replace the terminal bud. Some corms may be covered with papery or scaly remains of leaves.
Q. What are some examples of corms?
A. Examples of corms include gladiolus and crocus.
Q. What is a rhizome?
A. A rhizome is a thick stem that grows horizontally at or just below the soil surface. The stem is segmented by nodes. Roots grow from the bottom of the rhizome. Shoots and leaves may appear along the top and sides of the rhizome.
Q. What are some examples of rhizomes?
A. Examples of rhizomes include cannas, callas and german iris.
Q. What is a tuber?
A. A tuber is a swollen, fleshy portion of an underground stem that lacks a basal plate. A tuber lacks a protective tunic, but has a protective skin. Growing tips or buds appear over the surface of the structure from which shoots and roots may grow.
Q. What are some examples of tubers?
A. Examples of tubers include caladiums, potatoes and oxalis.
Q. What is a tuberous root?
A. A tuberous root is a swollen fleshy, unsegmented portion of a root. Growing buds form at the top end of the root.
Q. What are some examples of tuberous roots?
Q. How are bulbs measured?
A. Bulbs are usually measured in centimeters around the perimeter of the bulb. Thus, tulip bulbs that are advertised as "Size 12/14" are a minimum of 12 to 14 centimeters around the circumference of the bulbs. Some narcissus bulbs are advertised as "Topsize". This simply means that those bulbs are among the largest available for that particular variety. Daffodils are often advertised as "DNI", "DNII", or "DNIII." "DN" means "double-nose" and refers to the fact that multiple bulbs of various sizes are attached at the basal plate. "DNI" bulbs are the largest, and up to three flowers may grow from that bulb. "DNII" bulbs are large and two flowers may grow from that bulb. "DNIII" bulbs are the smallest and least expensive. Fewest flowers will grow from DNIII bulbs. "DN" does not refer to the actual measurement around the circumference of the bulb. However the bulbs are marketed, keep in mind that the largest bulbs cost more but will produce more flowers and be most satisfying.
Q. How are corms measured?
A. Corms are measured in centimeters around the perimeter.
Q. How are rhizomes measured?
A. Rhizomes are usually measured in centimeters length, but the largest are generally advertised as "topsize", which means that the rhizomes offered are among the largest available for that type.
Q. How are tubers measured?
A. The largest tubers available are generally advertised as "topsize", which means that the tubers offered are among the largest available for that type.
Q. How are tuberous roots measured?
A. Tuberous rooted plants may be advertised as "topsize", which means that the plants offered are among the largest available for that type. They may also be advertised according to the size and quality of the "division." A division is a portion of a larger clump that has been cut apart. The largest divisions are often called "#1 divisions."
Q. Is it okay to refer to bulbs, corms, rhizomes, tubers and tuberous roots as bulbs?
A. It depends on the company you keep. Among true friends who aren't trying to prove themselves, you may refer to them as bulbs. If you associate with self-conscious or pretentious persons who are keeping up appearances, you'd better get your terminology right. If you are pushed to the limit, you might refer to your most annoying critics as "fast and bulbous. Got me?"
Q. What are Fall-planted bulbs?
A. Fall-planted bulbs are those that are planted in the Fall for Fall (i.e. fall-blooming crocus) Winter, Spring or Summer bloom. Do not confuse Fall-planted bulbs with Fall-flowering bulbs, though some Fall-planted bulbs such as the crocus mentioned before may actually bloom in the Fall.
Q. What are Spring-planted bulbs?
A. Spring-planted bulbs are those that are planted in the Spring for Spring, Summer or Fall bloom. Do not confuse Spring-planted bulbs with Spring-flowering bulbs, though some Spring-planted bulbs may actually bloom in the Spring.
Q. When is the best time to plant Fall-planted bulbs?
A. Fall-planted bulbs must be planted in the Fall season, usually when soil temperatures drop below 60 degrees F.
Q. When is the best time to plant Spring-planted bulbs?
A. Spring-planted bulbs must be planted in the Spring season. Some of them can be planted as soon as the soil has begun to thaw and is no longer rock-solid. Others must be planted when danger of freezing has passed, or has warmed to about 60 degrees F.
Q. What kind of environment do bulbs prefer?
A. Every guide will recommend that the soil be well-cultivated and well-drained sandy/loam, free of weeds and pests, rich in organic matter and free of stones with a pH between 6.0 and 7.0, and that the average seasonal temperatures and rainfall be nearly perfect. Few such sites exist outside the fertile fields of bulb-producing regions such as The Netherlands, Belgium and Kashmir. But you can do the best with what you have with thoughtful preparation.
Q. How should the planting environment be prepared?
A. Choose a site that meets your bulbs' sun or shade requirements. Then try to replicate the environment of the fertile fields of bulb-producing regions such as The Netherlands, Belgium and Kashmir. Actually, I'm serious. Begin by taking a sample of your garden soil to your local Cooperative Extension Service office. They often provide collection bags. With each soil sample, indicate the type of bulb you intend to grow in it. For the most basic recommendations, you may be charged a nominal fee. For more information such as micro-nutrient and organic content you may be charged more. Follow the recommendations. Poorly drained sites can be improved by raising the height of the planting beds. Clay soils can be amended with gypsum, sand and/or loam. Sandy soils can be improved with organic compost. There is not much you can do about minimum winter- or maximum summer temperatures, so purchase only those bulbs that are recommended for your climate zone. Responsible irrigation practices may help in lieu of optimal rainfall.
Q. What does "naturalizing" mean?
A. "Naturalizing" means growing bulbs in an area where they can grow "naturally", perhaps multiplying and forming colonies as though they are native to the area. It means minimum maintenance. In order to achieve it, your soil and climate zone must be conducive to growth for that particular plant. Daffodils, narcissus and crocus may naturalize open fields and lawns if the climate is to their liking. Similarly, squill and scilla may colonize woodland areas. To be successful, the plants must be let alone to proceed through their own life-cycles without disturbance. In other words, avoid cultivating the soil, and don't mow down the yellowing leaves until they have dried fully.
Q. What kind of soil amendments should I use?
A. The soil amendments you should use depends upon the type of soil you have in need of amending. Common soil amendments include sulphur for lowering pH, limestone for raising pH, sand for helping drainage, clay for slowing drainage, gypsum for breaking up caking clay and compost for enriching the soil. Bone meal is especially good for bulbs. There are others which I don't have the time or space to name. Which you should use depends upon your particular circumstance. Your local Cooperative Extension Service should be helpful.
Q. What kind of fertilizers should I use?
A. There are many bulb fertilizer formulations on the market, each with their own claims to superiority. You may want to experiment with them to see which work best for you. Your soil sample report from your local Cooperative Extension Service will include recommendations based upon the results of the test. Following its instruction should be a good bet. A fine all-around practice for Spring-flowering bulbs is to mix 5 tablespoons of 10-10-10 fertilizer and 2 cups of bone meal per ten square feet area of bulb garden. Repeat the application when shoots appear, but be careful that fertilizer does not come into direct contact with plant tissue. Summer- and Fall-flowering bulbs should be fertilized more frequently but with less fertilizer per application. Apply 2 tablespoons of 10-10-10 fertilizer per ten square feet of garden area every two weeks until flower buds appear.
Q. How deep should bulbs be planted?
A. The proper depth may differ according to the type of bulb. But as a rule of thumb, bulbs should be planted three times as deep as the bulbs are wide. For example, if the bulb is 2" wide, plant it 6" deep. That means the bottom of the hole should be 6" deep.
Q. How deep should corms be planted?
A. The proper depth may differ according to the type of corm. But as a rule of thumb, corms should be planted three times as deep as the corms are wide. For example, if the corm is 2" wide, plant it 6" deep.
Q. How deep should rhizomes be planted?
A. The proper depth may differ according to the type of rhizome. But as a rule of thumb, rhizomes should be planted at or near the soil surface. For example, german iris should be planted with the lower end of the rhizome about 1" below the soil surface, but the top of the rhizome where the foliage appears should be showing just above the soil surface.
Q. How deep should tubers be planted?
A. The proper depth may differ according to the type of tuber. But as a rule of thumb, tubers should be planted 2" to 3" below the soil surface.
Q. How deep should tuberous roots be planted?
A. Most tuberous roots are attached to the growing point of the plants from which leaves appear. This growing point is called a "crown." The crown should be planted at soil level with the tuberous roots spread out below it in the hole.
Q. How should I care for the site after the bulbs are planted?
A. Other than keeping the area relatively weed-free, Fall-planted bulbs require very little care after planting. A 1" layer of mulch is very beneficial. During Spring, when growth begins, regular irrigation is helpful. For most types, the soil should be allowed to dry a bit between waterings.
Q. How should I care for the plants after flowering ceases?
A. After flowering ceases, most bulbs spend a few weeks building food reserves and preparing for dormancy. In order for them to build food reserves, foliage must remain intact and irrigation should continue. The leaves will begin to yellow over time. Though yellowing leaves are unsightly, they must be left alone until they dry and turn brown. After they turn brown, the foliage may be cut off. Avoid pulling dried foliage since the bulbs themselves may be pulled up by accident. Most bulbs, corms, rhizomes and tubers require drier soil during dormancy.
Q. Can bulbs be grown indoors?
A. Yes, bulbs can be grown indoors. Some may require special treatment in order for them to flower. Apart from providing adequate sunlight, moisture, and fertile potting soil, some bulbs may require forcing.
Q. What does "forcing" mean?
A. Many plants require a period of cold weather during dormany to induce growth and bloom. "Forcing" requires a method to provide that necessary period of cold. The method involves keeping the bulbs in a dark place at a temperature between 40 and 45 degrees Fahrenheit for up to 15 weeks. Paperwhite narcissus do not require a period of cold weather before blooming.
Q. How does one go about "forcing" bulbs.
A. Gardeners living in areas where winters are consistently cold may simply keep their potted bulbs in a covered trench or in a dark corner of an unheated garage as long as the temperature around the bulbs does not go below 40 degrees. Another common method is to store the bulbs at the proper temperature in an extra refrigerator. If you plan to keep them in a refrigerator, make sure that you do not keep fruit in the same place. Fruit slowly releases ethylene gas which will damage the flower bulbs.
Begin by planting the bulbs in well-drained bowls with a superior grade of potting soil. Pots with wider bases are best because they are less likely to tip over. After planting, mark the bowls to identify the bulbs, water well, drain and store. Some of the bulbs may begin to sprout during storage. When 15 weeks have passed, remove the bulb bowls from storage and keep in a cool, dimly lit area. Within a few days, the shoots will appear and turn green. When the shoots have turned green, they can be moved to a bright location to be enjoyed. Keep the soil moderately moist. The flowers may last for three or four weeks.
Q. How do I care for indoor bulbs after flowering ceases?
A. For some bulbs the answer is simple: throw them away. Bulbs that have been forced have usually used up their food reserves for blooming and have been deprived of the opportunity to rebuild them. Even transplanting them in the garden is usually an exercise in futility. Tulips, hyacinths and narcissus are examples.
Hippeastrum, however, are good examples of bulbs that can be grown indoors and brought into bloom again. After blooming, they may be planted in the garden in temperate climates, or one might continue to grow them indoors. When the bulbs are potted, they should be kept slightly moist. Avoid over-watering. When they begin to sprout, they should be fertilized with a balanced slow-release fertilizer. An all-purpose fertilizer should be fine, but some are available that are specially formulated for bulbs. If you choose to use a water-soluble fertilizer, feed them twice per month. Display them in a cool, bright area out of direct sun to encourage a longer bloom period. After flowers fade, allow the stems to yellow and droop. When they have shriveled, cut them off at the top of the bulb. Continue watering and fertilizing as usual until the leaves yellow. When the leaves have shriveled, they can be cut off, the bulbs unpotted and stored for later use.