How to Grow Amsonia Hubrichtii

Grow From Seeds

• 1

  Collect seeds from an existing Amsonia hubrichtii plant in late summer once the seed heads dry out and take on a cottony appearance. Extract the slender, 1/2-inch long seeds from the cottony matrix. Store the seeds in a plastic or paper bag until late winter.

• 2

  Prepare pots for the Amsonia hubrichtii seeds in late winter, around February or early March. Combine 3 parts garden soil with 1 part medium-grit sand to create a suitable potting mix. Fill 3-inch peat pots with the soil mixture. Leave 1/4 inch of space between the soil surface and the lip of the peat pot.

• 3

  Sow two seeds in each peat pot. Set the seeds horizontally on the soil surface. Press the dark brown, rice-like seeds into the soil to a depth of 1/4 inch. Push soil in on top of the seeds so they are completely buried. Pat the soil firm on top of each seed.

• 4

  Pour 1/8 cup of water into each pot of soil. Press the surface of the soil to expel the excess water. Let the peat pots drain for five to 10 minutes before moving them.

• 5

  Place the peat pots on a nursery flat or other type of tray to make handling them easier. Stretch plastic wrap over the peat pots, and secure it on both ends of the nursery tray.

• 6

  Set the nursery tray outdoors against a shaded, north-facing wall to cold-stratify the seeds. Leave the nursery tray outdoors under cold, shaded conditions for four to six weeks, or until daytime temperatures reach 68 degrees Fahrenheit in the sunshine.

• 7

  Move the nursery tray onto a sunny or partially shaded bench where temperatures stay above 65 degrees Fahrenheit during the day. Limit direct sun exposure to no more than 45 minutes on days when temperatures exceed 80 degrees Fahrenheit.

• 8

  Watch for germination three to four weeks after moving the Amsonia hubrichtii seeds to the warmer location. Thin the seedlings to one per pot if both seeds germinate. Remove the weaker of the two.

• 9

  Transplant the peat pots into a sunny garden bed with loamy, draining soil once the plants reach 4 inches in height.

Grow From Divisions

• 10

  Divide established and well-developed Amsonia hubrichtii plants in spring, around April or early May. Avoid dividing plants that have already put out flower buds or are actively blooming.

• 11

  Water the Amsonia hubrichtii plant thoroughly the evening before dividing it. Run water at the base of the plant for 10 to 15 minutes. Stick a finger into the soil to feel if it is moist at a depth of 2 to 3 inches.

• 12

  Measure out a 10-inch square portion near the edge of the mother plant. Dig down 5 inches on all sides using a trowel. Work the trowel underneath the Amsonia hubrichtii plant. Pry it from the ground.

• 13

  Cut the 10-inch square portion of Amsonia hubrichtii into four equal parts using a gardening knife. Cut straight down to ensure each division will have a fair share of roots.

• 14

  Transplant the divisions into a sunny bed with loamy, draining soil immediately after harvesting them. Choose a bed providing 24 inches of space around each Amsonia hubrichtii division.

• 15

  Dig a planting hole for each division measuring 5 inches deep and 5 inches square. Nestle them into the planting holes. Press the root ball into contact with the soil below. Fill in around the edges with garden soil.

• 16

  Water the divisions to a depth of 1/2 inch every two days for the first month after transplanting. Increase water to 1 inch every two days during hot weather.

Grow From Cuttings

• 17

  Grow Amsonia hubrichtii from cuttings in spring, around late March or early April. Select and pot the cuttings before the plant is setting buds or actively blooming.

• 18

  Select 4- to 6-inch long cuttings comprised entirely of new growth. Measure down from the tip of a non-blooming stem. Make a straight cut between two sets of foliage using pruning shears.

• 19

  Strip off and discard the feathery foliage from the lower half of each cutting. Dip the leafless ends of the Amsonia hubrichtii cuttings in 0.1-percent IBA rooting hormone.

• 20

  Pot the cuttings in individual 4-inch plastic pots filled with moistened, medium-grit sand. Press the cuttings into the sand up to the bottom sets of foliage. Press the sand firmly against the base of each Amsonia hubrichtii cutting.

• 21

  Set the potted cuttings outdoors under dappled shade or in partial sun. Avoid exposing the Amsonia hubrichtii cuttings to direct sunlight until after they have rooted.

• 22

  Pour 1/8 cup of water into each pot whenever the sand feels dry in the top inch. Let the sand dry out slightly before each watering to keep the cuttings from rotting.

• 23

  Check for roots in 21 to 30 days. Tug on the base of each Amsonia hubrichtii cutting to feel if it is attached to the sand by roots.

• 24

  Transplant the cuttings into the garden one week after rooting. Choose a sunny bed with loamy soil and good drainage.