Prior studies have demonstrated that a Gaspardo vacuum seeder provides less uniform seed spacing than a Stanhay belt seeder. It was hypothesized that the difference was primarily because of the greater seed drop height on the Gaspardo seeder. A Gaspardo metering unit was modified by adding a slide or an enclosed tube to guide the seeds from the release point (seed plate) to 1.0 inch (25 mm) above the bottom of the seed furrow. Seed uniformity tests were conducted with cabbage (Brassica oleracea), onion (Allium cepa), and mustard (Brassica juncea) seeds. The modified planter unit was compared with an unmodified unit. No improvement in seeding uniformity was noted with either the slide or the tube. In fact, seed placement uniformity was degraded with the addition of the slide and tube. Although it is probable that the seed spacing nonuniformity was caused by drop height, attempts to control the seed trajectory were unsuccessful.