One of the best choices for blue-flowering plants in an ornamental pond or freshwater lake edge, pickerelweed (Pontaderia cordata) grows best in abundant sunshine and water no deeper than 4 to 6 inches. The thickened roots called rhizomes spread outward in the mucky soil and send up heart-shaped leaves and a light blue to blue-violet flower spike from the stem tips, attracting butterflies and bees. This "marginal," or plant that grows on the shallow-watered edges of a pond, is grown readily in U.S. Department of Agriculture winter hardiness zones 3 through 10.
Locate an area along the shoreline of a freshwater pond or lake that receives at least six hours of direct sunlight daily and the water is shallow--1 to 6 inches deep--with a relatively flat bottom.
Fill a 5-gallon bucket with 5 to 10 lbs. of coarse gravel or variably sized garden rocks no larger than a grapefruit. Flat slate or stepping stone-like rock pieces suffice, too. Rest the wet rhizomes of the pickerelweed on top of the rocks in the bucket. Consider wrapping the rhizomes in a wet newspaper or rag to prevent sunlight or air from drying them out before planting. Place any dowels or stakes in the bucket, too.
Gather the 5-gallon bucket, garden shovel and waterproof rubber boots on the shoreline immediately next to the area you wish to plant the pickerelweed.
Put on waterproof rubber boots that are at least knee-high. Grab the bucket and the garden shovel and walk cautiously to the edge of the water using both the bucket and long handle of the shovel to help your balance and footing.
Rest the bucket in the water and allow it to sink to the bottom in the shallow water next to the spot you want to plant the pickerelweed.
Look at the size and shape of the plant rhizomes in the bucket to get an idea of the size of a hole needed to just cover them once in the soil at the bottom of the shallow water. The rhizome will be planted horizontally, so you want the hole to be deep enough to allow about 1 inch of mucky soil to lay atop it once planted. Look for any leaf buds and growing tips of stems or leaves. You will want to orient these buds and stems so that they are right at the soil line.
Gently pierce the garden shovel's blade into the mucky soil at a shallow angle to make a shallow furrow. Gently pile the mucky soil just to the side of the planting furrow. Avoid shuffling your feet a lot or making unnecessary movements with the shovel as this stirs the water and mud, clouding your view of the planting area.
Rest the rhizome into the shallow furrow, orienting any buds or stems/leaves upward. While holding the rhizome down in the furrow with one hand, pull the mud into the furrow and atop the rhizome with your other hand. Move slowly but with a cupped hand to move the mucky soil and reduce the clouding of the water.
Continue to scrape mud around the rhizome until it is covered in soil. Keep one hand atop the planted rhizome to prevent it from dislodging from the planting furrow and floating up.
Pick up a flat rock or handful of coarse gravel from the 5-gallon bucket with your free hand and place it over the newly planted rhizome. A baseball-sized rock is ideal to rest immediately atop the rhizome where no stems grow to weigh the rhizome down. Remove the hand holding down the rhizome once the rock is in place. Consider adding another rock or handful of gravel over the planted rhizome to ensure ample weight is in place to keep it in the soil.
Wedge a stick or dowel around the rhizome, if needed, to help support any erect stems already growing from the rhizome. Take care not to pierce the root and slightly angle the stick to hold the stem upright from the rhizome. Add additional sticks as needed to steady the newly planted pickerelweed. Criss-cross stakes if it helps support the stems and keep the rhizome snugly in the mud.
Cautiously and slowly walk away from the planting area, taking both the garden shovel and 5-gallon pail with you back up onto the shoreline.