Gerald Klingaman, Ph.D., is an emeritus professor of horticulture at the University of Arkansas. He is now working full time as Operations Director at the Botanical Garden of the Ozarks. He gardens in Fayetteville.
 

 

 

The Basics of Bulb Planting
by Gerald Klingaman, Ph.D. - posted 10/05/11  


Field of narcissus

Gardeners are an optimistic lot, always planning for the future and dreaming about what is yet to come. Nowhere is this optimism more apparent than when we plant bulbs. In our mind’s eye, we see glorious displays of tulips and drifts of golden daffodils splashed across our gardens like so much spilled paint. We can hardly wait! But sometimes these bulb displays don’t work out quite as well in reality as we thought they would when we planted them. If that’s happened to you, be assured you are not the first to experience this letdown, since bulbs have been inspiring and baffling gardeners for centuries. With such a long history of cultivation all over the world, bulb garden lore and legends have accumulated like scales on an onion.

 

BUYING BULBS & STORAGE

Nurseries and garden centers begin selling bulbs in late September and keep them on their shelves until November. Prices vary considerably, primarily based on the newness of the cultivar, bulb size and the quantity purchased. The largest bulbs, and hence the most expensive, may not always be the most practical way of achieving bang for your buck. If you have a set dollar amount to spend on bulbs, choosing the slightly smaller “landscaper” grades of bulbs and older cultivars is sensible. True, larger bulbs produce taller, more robust plants with larger flowers, but in my book a larger, more closely planted display of slightly smaller flowers has more impact than a small planting of large flowers. As far as I know, not even the chain stores have stooped so low as to sell bulbs so small they won’t flower.

Once you get your bulbs home, keep them in a dark location at room temperature until you are ready to plant them. The most common question I have had through the years about planting generally comes in April when gardeners discover a bag of bulbs they forgot to plant. Though they probably won’t do much, I always advise planting them because they surely won’t survive all summer stored in the garage.

           

SELECTING A PLANTING SITE


These ‘Remembrance’ Dutch crocus are more effective planted as a small intense spot of color, rather than scattered willy-nilly throughout the landscape.

The spring bulbs we grow evolved in open, sunny places with spring rains and dry summers. Over the centuries cultivation has softened the edges of these basic requirements, but it still provides a guideline for selecting the best planting site. Sharp drainage is necessary for most bulbs and prevents them from getting too wet and rotting in summer. The southern swamp lily (Crinum americanum) is an exception since it is native to swamps and the edges of water. Other bulbs that perennialize – especially Narcissus, Crocus (yes, I know they are really a corm) and hyacinth ­– tolerate summer wet and rainy conditions well. Tulips, however, have never gotten over their ancestral longing for the dry steeps of Central Asia. If tulip bulbs get too wet in the summer, they almost always rot away. Dutch growers avoid this problem by growing them in extremely sandy soils and by lifting the bulbs as soon as the foliage begins to die.

When you select planting sites for bulbs, assess the ability of them to naturalize in your area for a guide. Give short-lived plants like tulips the driest, sandiest sites. Summertime lifting of tulip bulbs is a possibility, but it means a section of the garden must remain unplanted until late May while the foliage matures and dies. Even then, the bulbs you dig will probably be puny compared to what you remember planting in fall because most of the hybrid tulips actually shrink after the first flowering in the Southern United States –making them much less desirable.

While most bulb species prefer full sun, many will tolerate some shade. Tulips, for example, do fine when planted in a somewhat shaded garden. At best, most tulips will survive only two or three years at best, so the effect from shade isn’t much of a concern. A second advantage of planting tulips in the shade is that it keeps the heat and wind at bay, extending the effectiveness of the display by as much as a week. Daffodils and crocus will grow in light shade, but if it is too heavy, their performance will suffer.

 

PREPARATION & PLANTING           


Iris reticulata is one of the easiest bulbs to grow, but use it in clumps because its diminutive size makes it easy to loose visually. The foliage grows knee-high before dying away in late spring.

Much has been written about how to plant bulbs. Discussion about double digging, bonemeal additions, planting depth and the like are all well and good, but they seem to overcomplicate the process. As long as you have reasonably good soil (a vegetable garden type of soil is ideal), and adequate aeration and drainage, even the most finicky bulbs should perform well. Double digging is fine aerobic exercise and makes more sense to me than joining a gym, but such heroic efforts are really not necessary to grow beautiful spring-flowering bulbs.

Fertilizing bulbs is optional if you ask me. Bonemeal is the old standby as far as soil amendments for healthy bulbs. I use it at a rate of 2 pounds per 100 square feet, although I’m not convinced that I get that much benefit from it, especially for short-lived bulbs like tulips. All bulbs respond to fertilization, but mostly from applications made during the growing season. For daffodils, feed about the time new leaves begin emerging in spring and again just before they reach full bloom. Fertilization does increase bulb size and can be useful for reviving a daffodil planting that quit flowering on a regular basis. On the other hand, we’ve all seen daffodil plantings that haven’t had a bit of fertilizer from even a distance in decades, and they are doing just fine. So, don’t lose too much sleep regarding this fertilization thing. 

Gardeners in Zones 6 and 7 can plant as soon as bulbs are available. As for procrastinators, Thanksgiving is the latest that planting should be put off. In Zones 8 and 9, you can delay planting until after New Year’s Day. Planting earlier will work but the bulbs tend to bloom ahead of the azaleas, which may not be desirable. In the southern part of Zone 9, tulips should be stored in the crisper of the refrigerator for about eight weeks prior to planting to ensure uniform blooming.

Gardeners, and the experts for that matter, don’t agree on the correct planting depth for bulbs. As a general guideline, plant the nose of the bulb about three times deeper than the diameter of the bulb. That means tulips and daffodils should be about 6 inches deep; crocus and the other minor bulbs 3 or 4 inches deep. The recommendation for deep planting in the South – with the idea that the soil will be cooler – is a good one as long as you live in an area blessed with sandy soil. If your garden has clay soil as mine does, deep planting is a death sentence.

           

PROPER SPACING

Plant bulbs close enough together to provide a show, but make adjustments for species that will naturalize. Most tulips should be planted on 6-inch centers if they are used for bedding out. This means that you need four bulbs per square foot. Because the likelihood of them surviving more than a couple of years is low, close spacing works fine. If you are using tulips for a spot of color, don’t be afraid to bunch them up. Crowd a dozen bulbs in a 12-inch circle. When planting daffodils, give them room to grow and multiply. Space standard-sized narcissus cultivars 8 to 12 inches apart; the dwarf varieties can be planted closer. Smaller-growing species such as crocus, grape hyacinth and reticulated iris should be spaced 4 inches apart if you are planting en masse, although sometimes I use these small bulbs as a color spot, crowding a couple of dozen bulbs in an area the size of a dinner plate. Avoid the temptation of wide spacing because bulbs need to grow in close proximity to their neighbors, otherwise they look lost and forlorn.

 

WILL MY BULBS NATURALIZE?

The accompanying tables give a fair indication of the likelihood of bulbs establishing themselves in the average garden. I’ve known of daffodil plantings that mark old homesites that have been abandoned for a century, and a crocus planting that persists after 30 years in a zoysia lawn, so it can happen. But, don’t get your heart set on keeping tulips going that long unless you have good conditions or choose the right kind. I maintained an Oxford tulip planting (a Darwin hybrid) for over 20 years – only losing it when some students dug it up by mistake – growing in a raised bed that had been backfilled with sand. Roots from a maple tree located in the flowerbed kept the bulbs bone-dry all summer. I’ve also had good luck with some of the species tulips in my rock garden. So, if you have a special place and a bit of luck, you may find tulips as easy to grow as daffodils – just don’t count on it.

 

TULIPS SUITABLE FOR USE IN SOUTHERN GARDENS


For a spot of color in a flowerbed, try planting a cluster of bulbs in a tight little clump.

SPECIES


TYPE


HEIGHT


SEASON


LIFE SPAN


SPACING


Tulipa greigii, T. kaufmanniana

& T. fosteriana

Early species tulips

8 - 12”

March

3+ years

6” on center

These early blooming bulbs are not so far removed from their ancestry that they have lost their wildness. T. greigii has mottled foliage. T. fosteriana ‘Madame Lefeber’ (‘Red Emperor’) is one of the best.


Various hybrids

Double tulips

10 - 18”

March-April

Short

6”

The early season doubles have parentage of the early species, bloom earlier and are shorter; the later selections are taller and less perennial.


Various hybrids

Single early, single late, triumph, parrot, lily-flowered, fringed

 16 - 24”

 March-April

 Short

 6”

These are some of the most beautiful tulips, but they are difficult to establish in Southern gardens. Don’t get too attached.


Darwins

Darwin hybrids

18 - 24”

April

3+ years

6 - 8”

One of the largest, most robust groups of traditional tulips, probably because of tetraploid characteristics. More likely to perennialize than others. ‘Apeldoorn’ and its many selections are a good place to start.


Various species

Species tulips

6 - 18”

March-April

3+ years

4 - 6”

A variable group of smaller tulips. Good for small, up-close viewing, not bedding out. T. clusiana, T. saxatilis, T. sylvestris and T. bakeri ‘Lilac Wonder’ are good for Southern climes.


 

 

COMMON NARCISSUS GROWN IN SOUTHERN GARDENS


‘Ice Follies’ is one of the dependable, short-cupped daffodils that is a fast multiplier and provides a nice display every year.

SPECIES


TYPE


HEIGHT


SEASON


LIFE SPAN


SPACING


Narcissus pseudo-narcissus

 Single flowered daffodils (Divisions 1- 3 & 11)

 12 - 18”

 March

 Generations

12” apart

The most common type, differing in the length of the trumpet; division 11 has a split trumpet. Usually yellow, but white, bicolors and pink shades are available. All are good, so try any you like.


Various species

 Double daffodils

 8-12” 

 March

 Long

 10”    

Usually shyly flowering, so be patient. Various kinds, shapes and colors. ‘Erlicheer’, ‘Manly’ and ‘Bridal Crown’ are examples.


 N. triandrus & N. cyclamineus

Multi-flowered daffodils (Divisions 5, 6 & 10)

 6 - 18”           

 March

 Long

 8 - 12”           

A variable group, but all have flat foliage with 3 to 6 blooms on the scape. Free flowering, some are fragrant. ‘Thalia’ and ‘Tête-à-Tête’ are prolific bloomers.


N. jonquilla

Jonquil

12 - 14”

March

Long

8”

Foliage is rush-like (rounded), with several fragrant, small blossoms at the end of the slender scape. Will reseed if happy. ‘Baby Moon’ is a cute selection.


N. tazetta

Paperwhite narcissus

14 - 18”

March

Long

12”

Used for indoor forcing because bulbs do not require chilling to flower, but foliage begins growth in the fall so is often tattered by spring. ‘Avalanche’, ‘Geranium’ and ‘Silver Chimes’ are all good.


N. x medioluteus

Poeticus daffodils

12 - 18”

April

Long

12”

Late blooming, delicate white flowers with very small central cups. Usually fragrant. ‘Actaea’ is an heirloom type and probably the best variety.


 

 

A FEW OTHER SPRINGTIME BULBS FOR SOUTHERN GARDENS


Allium giganteum

SPECIES


TYPE


HEIGHT


SEASON


LIFE SPAN


SPACING


Allium spp.

Flowering onions

12 - 36”

May-June

Long lived

Use as specimens

The ornamental onions are a grab bag of species with lots of potential for creative gardeners. A. christophii is short but with an 8” umbel; A. giganteum has a softball size head and grows 3 feet tall.


Crocus bicolor, C. chrysanthus,

C. sieberi, etc.

Species crocus

4 - 6”

February

Long lived

4”

The species crocus are daintier than the Dutch hybrids and make nice plants for massing in the lawn or for use in rock gardens. May reseed.


Crocus vernus

Dutch hybrid crocus 

6”

Late February

Long lived

4 - 6”  

Large flowering with more robust growth than others. Good for massing, forcing or planting in lawns. Bloom size is smaller in later years.


Iris reticulata

Reticulated iris      

6 - 8”

Late February

Long lived

5 -6”

Very dependable bloomers in shades of blue and purple. Foliage is short during flowering but grows to 16” by the time it dies back. 


Muscari armeniacum

Grape hyacinth

6 - 8”  

March

Long lived

5 - 6”  

 

Beautiful shades of blue. May reseed in Southern lawns and become a pest. The foliage starts growing in fall so it is often tattered by flowering time.


Hyacinthus orientalis

Hyacinth

8 - 10”

March

Medium

6”

A difficult plant to use effectively in the garden as it requires staking when in full bloom. For best show, cluster several in a tight mass or use for indoor forcing


 

(From Kentucky Gardener Volume III Issue VIII. Photos courtesy of Gerald Klingaman.) 

 

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