RHIZOMES, TUBERS & CORMS, OH MY!
Article and Photography by Linda B. Gay
Naturalizing bulbs are seasonal growers: Some like warm and even hot weather, while others like cooler temps, less sunlight and shorter days. The bulbs’ growth patterns are triggered by soil and air temperatures, followed by blooming at the right times chosen by the bulbs. The cycle continues with bulbs collecting energy prior to dying down in order to resprout the following season.
We refer to all as bulbs, but some could be rhizomes, corms or tubers. The key point is the word “naturalizing,” which is “of nature” and “adapting to the garden home.” Naturalizing bulbs are deciduous and die down after blooming, while perennial bulbs have foliage year-round, like crinum, amaryllis and agapanthus. Naturalizing bulbs listed in this article adapt to our Gulf Coast climate, which includes Zone 9a soil and air temperature and Zone 9a moisture and rainfall.
The big key to growing bulbs successfully is having soil with air channels, and you can make that happen by working expanded shale into our heavy clay soils. It is also beneficial to amend sandy soils with organic matter or compost combined with shale. You can plant seasonal bulbs in your flowerbeds, but when they go dormant, you don’t love them so much anymore.
ROCKS & ROOTS
We tend to overplant bulbs, and then we cut them in half with our shovels. So how do you have a nice garden of bulbs and every other plant you love? You create a rock garden around your shade trees where you cannot grow anything else there anyway.
Hopefully your shade trees are deciduous, so in the winter they allow cold-weather sun for the spring-blooming bulbs.
In a 10-by-10-foot area, use 40 pounds of organic fertilizer that will feed the tree, the new soil and the new plants. Use great care to not pile soil up on the base of the tree; leave the flare roots exposed on top. The organic fertilizer will help the tree roots go deeper, allowing you some more space to work in the bulbs.
SUMMER PERFORMERS IN THE SHADED ROCK GARDEN
Summer growing and blooming plants emerge when the soil temperature is consistently 70 degrees. In part shade, warming up takes longer.
• Caladiums are grown for their colorful foliage as their leaves resemble elephant ears. The first cool front will cause the plants to lie on the ground and start going dormant.
• Montbretia or crocosmia belongs to the iris family and multiplies underground with corms producing orange, yellow or red flowers.
• Kaempferias, or “Peacock Gingers,” are lovingly called the “Hosta of the South” because hosta doesn’t thrive here due to our warm winters. On the other hand, these rock-pocket plants display colorful leaves with the striking and contrasting colors of silver, black, green and purple topped off with purple iridescent blooms.
• Rain lilies, including zephyranthes and habranthus, bloom after a rain. Some species are sterile, while others reseed, so be careful about planting re-seeders in a small space. I like to pull off the seed heads and disperse into the lawn area. One day you’ll come home and have a flower or two waving at you from the lawn!
WINTER GROWERS FOR A SPRING BLOOM
After planting this group of bulbs, you’ll see them start to grow and have foliage all winter long, adding to the fullness of their space.
• Lycoris is one of my favorite fall bloomers and flowers before the foliage, hence the name “Naked Ladies.” There are several forms of this group, but the two most popular varieties are lycoris radiata that is red and lycoris aurea, a beautiful golden yellow.
• Narcissus produces single stalks with multiple flowers on the stalk. Some of the popular naturalizing narcissus are “Grand Primo” and “Erlicheer” (double form of “Grand Primo”).
• Spanish bluebells, also called “Roman Hyacinths,” are great naturalizers for shaded spaces and produce pink, blue or white bell-shaped flowers on 6-to-10-inch stalks.
• Paperwhites always come at the right time, great for forcing and giving as gifts around the holidays. Once bloomed, they can be planted directly into the garden for a new bloom next spring.
MORE TO CONSIDER
Some other bulb-like plants to consider are:
Alstroemeria — “Peruvian Lily”
Crinum — “Ellen Bosanquet”
Gladiolus byzantinus — Byzantine gladiola
Ipheon “Rolf Fielder” — “Star Flower”
Lapeirousia laxa — “Woodland Painted Petals”
Leucojum aestivalis — “Snowflake” or “Snowdrop”
Lilium “Triumphator” — Hybrid of Oriental and L.A. lilies
Lilium — Oriental and Asiatic
Sternbergia — Yellow crocus
A general rule of thumb when planting naturalizing bulbs is to plant the bulb twice the depth of the bulb. For example, if the bulb is 1.5 inches from nose to root, plant it three inches from the bottom of the hole to the top of the soil. So time to scope out your new rock garden and get growing!
Linda Gay is a horticulturist and gardener at The Arbor Gate Nursery in Tomball.