From our perspective as lupine plants (Lupinus spp.), we long to produce our magnificent, towering flower spikes. It is our ultimate purpose and our greatest joy. When we cannot flower, it is a sign that our fundamental needs are not being met. We will explain the common reasons from our point of view.
If you planted us from seed this season, please be patient. Our energy in our first year is dedicated to establishing a strong root system and healthy foliage. We are building the foundation for future glory. We often will not flower until our second spring. Conversely, if we are older plants (over four or five years), we may be entering our decline. Our flowering vigor diminishes with age, and our central taproot may become woody and less productive.
Light is our energy currency for flower production. While we can tolerate some shade, we truly thrive in full sun. If taller plants or structures now shade us, we receive insufficient energy to create our large, complex flower spikes. We may produce lush leaves but no flower stalks. We need a minimum of six hours of direct sunlight to gather enough resources to bloom properly.
We are particular about our soil. We require well-draining soil; our taproots are highly susceptible to rot in heavy, waterlogged clay. Soggy feet are a death sentence for us. More uniquely, we prefer slightly acidic to neutral soil. If the soil is too alkaline, we cannot properly access certain nutrients, especially iron, which leads to chlorosis (yellowing leaves) and a severe lack of energy, preventing flowering.
Feeding us incorrectly is a common mistake. We are legumes and have a symbiotic relationship with rhizobia bacteria that fix nitrogen from the air. If you give us a high-nitrogen fertilizer, you are flooding our system with a nutrient we can already procure ourselves. This excess nitrogen tells us to focus all energy on producing vast amounts of leaves at the expense of flowers. We need a fertilizer higher in phosphorus (the middle number on the package) to promote bud formation.
After our initial magnificent bloom in late spring or early summer, if our spent flower spikes are left intact, we divert energy into producing seed pods. Our biological imperative is to reproduce by seed. If you allow this, we believe our job is done for the season. However, if you cut the spent flower spike down to the base, it tricks us into attempting a second, smaller flush of blooms later in the summer to try again.
Aphids are a particular nuisance. They suck our sap, which is the very lifeblood we need for flower production. A severe infestation can weaken us immensely. Additionally, a late, hard frost after we have sent up our tender flower bud stalks can damage or kill them entirely. If our budding reproductive parts are frozen, we simply cannot recover and flower that year.
