Lupin planted in narrow rows has also been reported to mature earlier. But since lupin can be susceptible to weed infestations, some growers may need to use row spacings of 18 inches to 22 inches, to allow for cultivation. Slightly higher yields or improved plant population results from higher seeding rates, but high seed costs encourage lower seeding rates. Growth Characteristics Lupin differs from other grain legumes in its growth habit. Maximum vegetative growth rate occurs during flowering.
Environmental conditions influence the process of flowering and setting of pods.
Inoculation Yield increases of approximately 60 percent have occurred in Minnesota due to inoculation of lupin seed with Rhizobium lupini, the appropriate nitrogen-fixing bacteria for lupin on fields not previously planted to lupin. Since inoculant is inexpensive, lupin seed should be treated to ensure good nitrogen availability. Under most circumstances lupin does not need to be fertilized. Nitrogen fertilizers are not recommended for lupin because of the recommendation that lupin be inoculated at planting. Lupins have the ability to use existing P in soil that most crops can't use.