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Soil Needs of Container Bulbs
Mix the Right Soil for Bulbs
Bulbs grow best in containers filled with fast-draining but moist and well-structured soil. Best are loose, fast-draining soil mixes that retain moisture and are equal parts sand, silt, clay, and compost.
These soil conditions are closely resemble those found naturally at many sites where most bulb species grow wild.
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Exceptions are the tropical and evergreen bulbs. For them, ordinary high-organic potting soil gives them texture and moisture similar to the conditions found in the soils of their native forests.
For the rest of the bulb species, follow these directions:
Potting soils and mixes often have much higher levels of organic materials than are ideal for bulbs. Fix them by adding a mixture of sand and fine silt equal in quantity to the potting soil.
For a typical container, also add in a tablespoon of low-nitrogen granular fertilizer, such as 4–10–10 formulation, in each gallon (4.4 l) of prepared soil mix, blending it evenly throughout the soil.
This starter fertilizer will help the bulbs establish their roots and feed early foliage development.
Fertilizer and Container Bulbs
Soil fertility is more important for bulbs growing in containers than it is for outdoor bulb plantings.
Start container bulbs off with rich soil containing low nitrogen but high phosphorus and potassium.
Containers quickly lose their initial load of soil nutrients. Water-soluble compounds such as nitrogen dissolve as bulbs are irrigated. It leaches out of the soil and drains away.
The other major nutrients—phosphorus and potassium—chemically bind to soil minerals. They soon become unavailable to your bulbs.
Keep bulbs healthy, especially after their shoots emerge from the soil. Applying liquid organic 10–5–5 fertilizer, diluting it to one-half the package-recommended rate each time you water, usually weekly or semi-weekly.
Foliar fertilizers are another option. Spray them directly onto the foliage and stems of growing bulbs. These special fertilizers absorb directly through the bulb’s foliage, bypassing the container’s soil and plant’s roots.
Stop fertilizing after flowers begin to open, but keep watering regularly so that the container’s soil remains damp. Withhold water once the foliage begins to yellow and wilt, but before it shrivels and dies.
When the foliage has died to the ground, place the pot of bulbs and dry soil into a dry, warm spot out of direct sunlight for storage.
If you wish, instead you may lift the bulbs. Always cure them after lifting, brush them clean, and store them as directed [see: Dividing Bulbs and Roots and Curing and Storing Bulbs].
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