Thursday, March 4, 2010

Naturalizing Bulbs

I’d like to make a pitch for the lesser spring bulbs. These lovely plants not only return year after year but will multiply. This is called naturalizing and it is what makes these bulbs the most bang you can get for your buck. I’ll list them chronologically by bloom time; the actual month of bloom may vary by geographic area or due to changing weather patterns.

The first blooms to appear are the snowdrops (Galanthus); snowdrops these dainty blossoms usually appear mid-January. They prefer to be planted “in the green” so look for plants that are up and growing at the nursery. Right on their heels are the bright yellow aconite (Eranthis).

Bulbous Iris bloom in early February. Iris danfordiae is brilliant yellow, like a tiny daffodil. Iris reticulata and Iris histrioides have lovely blue or purple flowers.  There are several well known hybrids with intricately etched blooms in pale silvery blue or purple. Before the irises are done, the early crocuses are coming on strong. By choosing varieties with different bloom times, you may have crocus blooming for monCrocusths. Crocus tommasinianus starts the show as early as late February, followed by C. chrysanthus; C. flavus and  C. vernus bloom last, in April.

By early March the dark blue Scilla are making a statement. If they happily colonize, they look like a sapphire pool while blooming. Try them under the lovely butter yellow blooms of Corylopsis pauciflora. In March the Chionodoxa bloom in shades of pale blue or pink. Ipheion begins to bloom in March and continues into April. They are sweetly scented and periwinkle blue, lovely with daffodils. Surprisingly, hyacinths perennialize; they seem like they would be divas, but I have a group that has returned for four years.  Their scent is delicious but powerful; plant them along a walkway or by a door, but think twice about taking them inside!

In April, the daffodils finally bloom, although their strappy leaves have been up for months. You can extend your daffodil display by planting groups with different bloom times. An early variety is Narcissus cyclamineus with reflexed petals. N. c. ‘Tete a Tete’ is a miniature. The classic Trumpet daffodil is a mid-season bloomer as is the Triandrus daffodil.  N. t. ‘Thalia’ is my personal favorite of all the daffodils. Late bloomers include the doubles, N. ‘Cheerfulness’ and N. ‘Winston Churchill.’

If you are going to grow tulips, I enthusiastically recommend species tulips. They usually go by their Latin names: Tulipa acuminata, T. humilis, T. linifolia, T. saxatilis. Originally from the Mediterranean, Asia Minor and the Caucasus, these lovely little gems offer flowers in dazzling colors. They perennialize better than hybrid tulips and are wonderful for naturalized drifts and rock gardens where they will not be overwhelmed by early emerging perennials. Many are quite small; their height is usually less than 8” although some grow larger. 

Generally, all of these bulbs appreciate a position that is sunny during the growing season. Remember that many deciduous trees and shrubs are bare or sparsely leafed out January through April and bulbs will happily naturalize beneath them.  Well drained soil is non-negotiable-they abhor wet feet.  If you are unsure about your site, it is worth it to perform a percolation test. Dig a hole 2 feet deep, any width. Fill the hole with water and let it drain completely. Refill hole with water. Place a measuring stick in the hole, or mark soil on the side of the hole with a nail or twig. Measure the drop in water level after 30 minutes and again in one hour and calculate the average drop in level/hour.  If, on average, the water level drops less than ½” per hour, the soil drains poorly; if ½”-1”, the soil is moderately well drained. If the water drops more than an inch per hour, the soil is well drained and suitable for bulbs.

Plant them in early fall so they have time to make their roots while the soil is still relatively warm. They should be planted at a depth twice the height of the bulb and 2” apart. Remember that in order to return and bloom again, the foliage must be allowed to die back undisturbed. The foliage creates the energy that is stored in the bulb for next year. Plant bulbs with perennial companions that will shoot up to cover their ripening foliage.  Good choices include Geranium, Nepeta, Brunnera, Hemerocallis, Campanula and Hosta. Deciduous grasses, such as Hakonechloa work well.

An excellent web resource for photographs of all of these bulbs is John Scheepers. Give these hardworking beauties a try and see if they don’t “grow on you.”

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