   It's Fall Bulb Planting Time - September 30, 1998 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County As we start preparing our gardens for winter, make some time and space in the garden for some bulbs. They do require some soil preparation and a little care, but the rewards are guaranteed: excellent spring and summer color. The term "bulb", is often used to describe a plant which utilizes an underground plant part to store energy to enable them to survive periods with less than optimal conditions (i.e., drought, freezes, fires, etc.). From a botanical perspective, what most people call "bulbs" can be either true bulbs, corms, tubers, or rhizomes. Onions, lilies, daffodils, and tulips are examples of true bulbs. From the plant science perspective, a true bulb is a large bud that consists of a very short stem with fleshy leaves or scales. Energy (sugar and/or starch) is stored at the thickened bases of the leaves. Roots grow from the base of the stem. Corms appear similar to bulbs but differ by having thinner, smaller leaves which have no energy storage function. Instead, energy is stored within the stem of the corm. Gladiolus, crocus, and cyclamen grow from corms. Tubers are swollen underground roots that have buds or "eyes" as found on potatoes. Each bud produces a separate plant. Dahlias and some begonias grow from tubers. Rhizomes are very similar to tubers, are usually found growing near the soil surface and in a horizontal position. German irises grow from rhizomes. Both tubers and rhizomes serve as energy storage structures. The science lesson is not over yet. It is important to understand the energy storage function of any plant to ensure it's success. For instance, if a German iris had the leaves cut back severely during spring and early summer, then it may not produce large, showy flowers during summer. The leaves conduct photosynthesis to produce the energy needed for flowering and to satisfy the metabolic needs of the plant during dormancy. By promoting leafy growth, you are also allowing the bulbs, corms, tubers and rhizomes to store energy for the future. The science lesson is not over yet. It is important to understand the energy storage function of any plant to ensure it's success. For instance, if a German iris had the leaves cut back severely during spring and early summer, then it may not produce large, showy flowers during summer. The leaves conduct photosynthesis to produce the energy needed for flowering and to satisfy the metabolic needs of the plant during dormancy. By promoting leafy growth, you are also allowing the bulbs, corms, tubers and rhizomes to store energy for the future. Avoid planting bulbs in areas with shallow caliche or otherwise restricted drainage. Likewise, avoid areas where bermuda grass is present. Root knot nematodes can also cause problems with bulbs. Many readers are probably thinking I've just exclude 90% of the Verde Valley, but there are solutions to these problems and it does get better from here. For instance, most bulbs prefer full sun during the late winter and early spring. Organic matter additions are necessary improve drainage, increase nutrient holding ability and help acidify our alkaline soils. Manure will work, but it must be well decomposed and should be worked into the soil six weeks before planting. Phosphorus fertilizer is also beneficial to bulbs. Remember to consider planting depth when preparing soil. It should be prepped deep enough to have a significant effect on the rooting zone. For instance, it would do little good to improve the soil to a depth of six inches and then plant the dahlia tuber six inches deep. Some bulb flowers can get very tall while others are quite compact. Plan accordingly by grouping taller plants at the rear of the bed. Small plants look nice when planted in small clusters or among rocks. Time of blooming is also variable. By doing some research and trying to visualize the results, one can design a bed that will have color throughout the growing season. This article is enough to get most people going. If you are apprehensive, then start small and see how it goes. The University of Arizona Cooperative Extension has publications and information on bulbs and other perennials. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |