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The plant parts that form underground and anchor the flower are an essential part of the lifeline to the plant's health. Most of the time, these underground shoots are the roots. But in some instances, they are underground stems that we mistake as roots! For example, rhizomes, bulbs, tubers, and corms are in this category. These are storage containers full of starch and energy like carbs that benefit the plant to survive unfavorable weather conditions.
Rhizomes are thickened stems that develop horizontally under the soil surface. Rhizomes have green bumps called eyes or buds that extend along the top and sides. These serve as growing points for the stems and foliage to emerge and surface the soil. Some rhizomes are fleshy or slender and elongated with internodes.
Tubers are thick, knobby, and enlarged portions that store food for the plant and cluster at the bottom of the stem growing vertically below the soil's surface. New shoots will emerge from the "eyes or buds" of this rooting system.
Bulbs are usually a rounded, ball-like shape with a narrowing tip from which the stem and leaves emerge. They often have a papery layer on the outside called a tunicate. This layer protects the bulb from drying out during dormancy. Although, not all bulbs have this protective layer, such as lilies, and can bruise easier and dry out faster. Notice the flat part on the bulb. This part is the bottom where the roots will grow, and new offsets will emerge. If you were to dissect it down the middle, you would discover a miniature flower waiting to emerge.
Corms appear comparable to bulbs without fleshy scales. Corms will be both rounded or slightly flattened with a distinct upright orientation on top. The parent corm withers away at the end of the season but produces cormels or cormlets from eyes on the primary corm's top or side. Larger new corms will flower the following year, as smaller cormels may take a while to mature enough for blooming.
How To Plant Rhizomes, Tubers, Bulbs & Corms
How To Plant Calla Lilies & Canna Lilies:
To plant, ensure the eyes are facing upwards. Refer to each plant for the specific directions on planting and spacing.
To propagate, split into divisions including at least one eye with the root system. Replant separately.
- Calla Lilies & Canna Lilies are Rhizomes
- Check our chart below for the approximate time your area has its last frost of the season. Around that time, check the forecast for any lingering cooler weather conditions that could damage the tender growth emerging moving forward. Select a safe date to plant after all knowledge of temperatures below 40°F is passed.
- Choose a site in zones 3-7 that provide 6-8 hours of full sun. In higher zones, provide partial shade in the afternoons with a total of 4-6 hours of sun.
- Prepare the soil by adding soil amendments if it isn't well-draining and the earth is heavy. The soil pH range should be 6 to 7. A pH monitor can determine your range. Add amendments such as lime or aluminum sulfate to the soil, depending on your numbers.
- Plant each rhizome generally 3 to 4 inches deep, 6 to 9 inches wide hole, and 12 to 18 inches apart after the last frost in your planting zone. Place your rhizomes in a horizontal position, so the eyes are facing upward. Add compost or soil conditioners and mix in with the native soil.
- Add an organic fertilizer such as bone meal rich in phosphorus, calcium, and a trace of nitrogen. These nutrients will help the roots establish.
- A soluble bulb fertilizer like 3-5-3 can also be a part of the soil amendments to give your bulbs a good start.
- Water the plantings afterward, being careful that the water drains well around the planting area. Continue to water after planting and throughout the growing season when the ground is dry. Use the shower setting on the nozzle to give it an even, rain-like watering to avoid erosion and divots in the garden bed.
- As the foliage emerges, repeat the bulb fertilizer application each month until they start blooming. Stop when the Calla's start flowering to help extend the life of the bloom.
How To Plant Caladiums & Elephant Ears:
Caladiums & Elephant Ears are tuber plants. To plant, find the bud and place it facing upward, bury it two to three times the tuber's height. Refer to each plant for the specific directions on planting and spacing.
To propagate, divide the tubers into sections, with each segment including an eye or bud. Replant separately.
How To Plant Amaryllis, Daffodils, Tulips, Snowdrops, and Hyacinths:
Amaryllis, Daffodils, Tulips, Snowdrops, and Hyacinths are bulbs. To plant, face the basal plate (flat side) downward and the pointy side upward. Usually, you'll bury the bulb two to three times the bulb's height. Dig the hole at least three to four times as wide and amend the soil if it's heavy or clay. Refer to each plant for the specific directions on planting and spacing.
After 2-3 years, bulbils can be removed off the base plate (rooted area) and replanted separately at the same depth to propagate.
How To Plant Gladiolus & Crocus:
Gladiolus & Crocus are Corms. To plant, face the basal plate (flat side) downward and bury two to three times the corm's height.
To propagate, divide the corms at the end of the blooming season and plant them separately.
Gladiolus and crocus are examples of corm plants.
When to Plant My Bulbs
Summer blooming bulbs will begin in the Spring after the last threat of frost in your planting zone. Check your planting zone here. Check our chart for the approximate time your area has its last frost of the season. Around that time, check the extended forecast for any impending cooler weather conditions that could damage the tender growth emerging after planting. Select a safe date to plant after all knowledge of temperatures below 40°F is passed.
When To Plant Summer Bulbs Based On Zone Chart
Planting Zone Map
Schedule to plant blooms that show off in the early Spring in the fall during September and October when the soil begins to cool.
Prechilling in Warmer Climates
If you are planting in warmer zones (8-11), the bulbs will need a "pre-chilling" to produce a bloom. The chilling period lasts 10-14 weeks in a refrigerated compartment free of ripening fruit or ethylene gas exposure. Temperatures at 35°F to 45°F will stimulate a biochemical response that formulates the flower and root growth. Begin this process in mid-October and plant them outdoors fourteen weeks later.
The best area to plant in warmer climates is where there is protection from the afternoon sun. Four to six hours of morning to midday sun would be ideal. The topsoil can be mulched 3-4 inches deep after planting to retain moisture and keep weed seeds from sprouting. Mulching will also keep the ground cool.
If you're ready to add some new plants to the garden this Spring, check out our bulb offerings here! Please share your pictures on Instagram and Facebook of your bundles of beauty!