Crocosmia. Photo from the NOLA.com|The Times-Picayune
A crinum decorates the bed near the lilly pond in front of the Conservatory of the Two Sisters at the New Orleans Botanical Garden. Photo from the NOLA.com|The Times-Picayune
Technically, calla lily flowers are tiny and located on the yellow column, which is botanically known as a spadix. The showy white structure is a modified leaf called the spathe. This flower structure is common among arums. Other well-known arums include the peace lily (Spathiphyllum), Anthurium and Jack-in-the-pulpit (Arisaema triphyllum). Photo from the NOLA.com|The Times-Picayune
Caladiums. Photo from the NOLA.com|The Times-Picayune
Agapanthus. Photo from the NOLA.com|The Times-Picayune
Agapanthus flowers. Photo from the NOLA.com|The Times-Picayune
Crocosmia. Photo from the NOLA.com|The Times-Picayune
A crinum decorates the bed near the lilly pond in front of the Conservatory of the Two Sisters at the New Orleans Botanical Garden. Photo from the NOLA.com|The Times-Picayune
Technically, calla lily flowers are tiny and located on the yellow column, which is botanically known as a spadix. The showy white structure is a modified leaf called the spathe. This flower structure is common among arums. Other well-known arums include the peace lily (Spathiphyllum), Anthurium and Jack-in-the-pulpit (Arisaema triphyllum). Photo from the NOLA.com|The Times-Picayune
Caladiums. Photo from the NOLA.com|The Times-Picayune
Agapanthus. Photo from the NOLA.com|The Times-Picayune
Agapanthus flowers. Photo from the NOLA.com|The Times-Picayune
Hoping for beautiful flowers and lush foliage in your garden this summer? Consider adding bulbs to your beds. Most summer-flowering bulbs are native to tropical and subtropical climates and will reliably bloom here for many years. They make colorful additions to flower gardens and landscapes, and now is a great time to plant them.
In common usage, the term "bulb" is used to describe any fleshy below-ground structure produced by a plant, including bulbs, tubers, corms, rhizomes and tuberous roots. Although generally not critical, it can be important to know that these structures do differ significantly from one another and can influence how the plant is cultivated and propagated. Summer bulbs are those that bloom roughly from May through September.
For instance, you would never cut a true bulb in half to propagate it -- that would kill it. Crinums and lilies (Lilium species) are examples of summer-flowering bulbs that grow from true bulbs. You may, however, divide clumps of bulbs into individual bulbs.
On the other hand, I would not hesitate to cut a large caladium tuber in half to propagate it. Tubers are easily propagated this way.
Because they are such a large and diverse group of plants, providing general instructions on care for summer-flowering bulbs is difficult. Indeed, no matter what situation you have, there are almost always a few kinds of bulbs that will thrive for you.
Most summer bulbs prefer good drainage, although calla, canna, crinum, spider lily (Hymenocallis), Louisiana iris, yellow flag and some gingers are a few exceptions. Full to part sun (six hours or more of sun a day) is important to most of these plants for healthy growth and flowering, but many, such as achimenes, caladium, gingers and bletilla, do fine in shadier spots.
Summer bulbs typically have a dormancy period when the foliage dies off and the bulb rests. This period generally occurs in the winter. A few bulbs are normally evergreen, such as agapanthus and some gingers (but they will go dormant if the winter is cold enough and several hard freezes occur).
As bulbs enter dormancy, growth stops, and the foliage will become yellow, then brown. At that time, the foliage may be trimmed back to the ground. Be sure to place markers where the dormant bulbs are located. It can be hard to remember their exact spot when nothing shows above ground, and you can accidentally dig into them with a shovel if you're not careful.
Avoid removing healthy, green foliage. It is the leaves which manufacture the food which is stored in the bulb. If you frequently remove healthy foliage, you will reduce the plant's ability to create food, weaken the bulb, lower the vigor of the plant and reduce flowering.
When planting summer-flowering bulbs, you should dig generous amounts of organic matter, such as compost, aged manure or soil conditioner, into the area before you plant. A light sprinkling of a general purpose granular fertilizer once or twice during active growth beginning in March and ending in August is sufficient for most summer bulbs.
Seed pods may form after a summer bulb has bloomed. Unless you're breeding the plants or want to grow some from seeds, allowing the seed pods to develop is a waste of energy for the plant. I recommend that you remove the old flower spikes or developing seed pods as soon as you notice them. Growing most summer bulbs from seed is not difficult, but requires patience as most will not bloom until they are at least two to three years old.
Propagate spring-flowering bulbs by dividing the clumps when they are dormant or just waking up in early spring. Some bulbs, like crocosmia, do best divided every year or two while others, like agapanthus, prefer to be left alone.
There are a number of outstanding summer bulbs for our area. One of the best known and most popular is the caladium, which is grown for its colorful foliage rather than flowers. You can buy caladium tubers now and plant them directly into the garden. You may also plant pre-sprouted tubers that are available at many local nurseries. Unless you need growth immediately, the unsprouted tubers are generally a better buy. Tubers left in the ground last year should be up and growing by now, so keep an eye out for them. Caladium foliage is present from April through October, and the colorful, bold leaves combine well with other shade-loving plants.
Gingers are a natural for New Orleans landscapes and grow well in partially shaded conditions. They grow from rhizomes. Because they're native to the tropics, ornamental gingers thrive in our hot, humid summers. Despite their tropical origins, however, a large number of gingers are root hardy here and make excellent permanent additions to your yard.
The plants we call gingers actually include many genera, with different sizes, growth habits and shapes of flowers. Low-growing gingers, such as Kaempferia and Globba, make great ground covers, while larger gingers reaching 6 to 12 feet, such as Costus, Alpinia and Hedychium, can be used for accent, screens or background plants.
My favorite true lily that grows well here is the Philippine lily (Lilium philippinense). Looking for all the world like a giant Easter lily, the Philippine lily blooms in late summer, around July and August. The large white trumpet flowers occur in a cluster at the top of plants 5- to 7-feet tall. It thrives in our heat and humidity, and I've never seen any major insect or disease problems.
These are just a few of the many outstanding summer-flowering bulbs for our area. The following lists will help you get started.
Summer bulbs for full sun to part sun: agapanthus, belamcanda, calla, canna, crinum, crocosmia, dahlia, dietes, garlic chives (Allium tuberosum), gladiolus, gloriosa lily, habranthus, Tropical Giant spider lily (Hymenocallis), lilies, lycoris, oxalis, stargrass (Hypoxis angustifolia), tigridia, society garlic (Tulbaghia), zephyranthes.
Summer bulbs for part shade to shade: achimenes, alpinia, arisaema, bletilla, caladium, calla, costus, curcuma, globba, hedychium, hymenocallis, kaempferia, neomarica, oxalis.
Dan Gill is a horticulturist with the LSU AgCenter.
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