When fall has arrived, it’s time to think about…spring! Yes, cool autumn temps urge us to decorate with pumpkins, pick apples and romp through fallen leaves, but those fall traditions will be around for months. For home gardeners living in cold-winter regions, the window for planting spring-blooming bulbs is only open for so long, so you had better get planting before Mother Nature closes it for the season!

Three cut bulbs

Ever wonder what’s inside a bulb? This is a cross-sectional view of a tulip, hyacinth and narcissus bulb when they’re ready to be planted in the fall. The fully formed flower bud is visible at the end of the short stem.

Photo Credit: Gerald L. Klingaman

Tulips

Available in all shapes, sizes and colors, tulips are one of the most recognizable true bulbs of spring.

Photo Credit: James H. Schutte

Cut lily bulb

Lily bulbs are not covered in a tunic, and flower buds are not formed until the spring, when the new shoot begins to grow.

Photo Credit: Gerald L. Klingaman

Hyacinths

Early blooming hyacinths bring intoxicating fragrance, as well as beauty, to the springtime garden.

Photo Credit: Mark A. Miller

Dug up tulips

These tulips were dug the first year after planting and after the foliage matured. Notice the assortment of large and small bulbs that were produced. Only a few of these will make a good bloom their second year.

Photo Credit: Gerald L. Klingaman

Narcissus ‘Barrett Browning’

Like its daffodil counterparts, Narcissus ‘Barrett Browning’ is a hardy, long-lived, clump-forming bulb.

Photo Credit: Gerald L. Klingaman

Much of the beauty of the spring garden is derived from the bulbs that were planted in fall. To most gardeners, the word “bulb” is used as a general term for all bulbous plants that are buried underground a couple of seasons prior to bloom time. But technically, that doesn’t make them “true bulbs.” Some might be corms (like Crocus), tubers (like Anemone) or tuberous roots (like Ranunculus).

To the botanist, a bulb is an underground storage organ with a vertical stem axis surrounded by swollen leaf bases. The botanical term “geophyte” is used to describe all the storage types – bulbs, corms, rhizomes and tubers – that gardeners collectively call “bulbs.” They’re all great plants, but the most spectacular flowers come from the true bulbs.

True bulbs are found only among the monocotyledonous species – those plants that have one seed leaf at germination. Most of the true bulbs are found in two plant families: the lily family (Liliaceae) or the amaryllis family (Amaryllidaceae), although many botanists are now breaking these old classification categories into many subsets at the family level.

The bulbous habit of growth occurs almost exclusively in temperate parts of the world beyond 30 degrees north and south latitude. The geophytic lifestyle developed as a protection mechanism to allow plants to get through hard times, especially drought and cold. Most bulbous species are native to either grassland habitats or mountainous regions.

In grasslands, bulbs are usually spring-blooming with the foliage dying down by early summer, when the grasses suck all of the available water from the soil. In mountainous areas, the bulbs flower quickly during spring, mature their foliage during the short summer, then disappear belowground during the long, cold winter.

Bulbs actually have all the parts and pieces of an oak tree but have gotten rid of all the superfluous stuff, leaving behind just a dormant bud. The stem of a bulb is called the “basal plate.” It grows vertically just like an oak tree, but it’s only a few millimeters long. The basal plate has nodes where leaves and new branches are produced and, at the end of the stem, a flower is formed. At the base of the stem, roots form just like a normal oak tree’s would.

The accompanying photos show a cross-sectional view of a tulip, a hyacinth and a daffodil bulb. These species are what we call “tunicate” species, with the leaf bases enclosed in a papery covering. Lilies have “non-tunicate” bulbs, with the individual scales not encased in this protective sheath. The tunicate species generally show more drought tolerance than the non-tunicate species.

The three bulb species shown in the first picture have three distinct means of maintaining the bulbous lifestyle. The tulip, native to the cold and dry steppe region of Central Asia, replaces its bulb each year after flowering. The food reserves of the original bulb are depleted to produce the stout stem, leaves and flowers we so admire in spring. If your area’s climate is perfect – with cool conditions and just the right amount of moisture – the foliage will persist long enough to regenerate a big, healthy bulb for the next blooming season. But when conditions aren’t so perfect (as is the case in most gardens), the big bulb that was originally planted is replaced with a small bulb after blooming, and after two years it’s just too small to flower again. A bulb that’s too small to flower produces just a single leaf that splays out across the ground.

Hyacinths (and most other bulbs) retain their bulb from year to year and build on what they had from the start. If conditions are good, the bulb will grow a bit larger; if conditions are not so good, it will be a bit smaller. But the bulb doesn’t start over anew each year, so this lifestyle choice typically makes these kinds of bulbous plants dependable repeat bloomers in the garden. Allowing the foliage to remain as long as possible after the blooms fade will help ensure a bigger bulb for the coming season.

Daffodils branch freely, while others (like hyacinths) are slow to branch. In bulbs, this characteristic is referred to as “producing offsets.” Because daffodils branch so freely, it’s not uncommon for a clump formed from a single bulb to become so crowded that it stops flowering after 5 years or so. Lifting, dividing and resetting the bulbs every 5 years or so in fall will allow the bulbs to grow large enough to flower.

So before you pull out the pumpkins and turkeys for fall, spring ahead and envision a blooming garden in April. With some basic planning and planting in autumn, you can make your entire yard shine with the brightest of bulbs!