When your new clematis plants arrive or you purchase clematis and bring them home, it’s time to think about how you will grow them, including when and where you will plant them.
We recommend that your clematis have enough root mass to reach to the bottom of a gallon pot. This translates to about 8 inches of root length, with ample lateral roots and actively growing white tips on some of the roots.
If your new clematis plants from any source are not ready to plant in the ground, growing them for a interim period in larger containers than they are currently in while they produce more roots will help ensure your clematis get off to a good start in ground.
Spring and early fall are the ideal times in most gardens for planting clematis outside, as precipitation and temperatures tend to be more moderate at these times. Clematis plants that are going to be grown in containers can be planted in their new containers any time during your growing season.
Growing clematis in larger containers, even for a period of years is a beautiful option for some in the garden, or on the patio or deck.
When your clematis plants are ready to be planted outside, start by selecting a location in an area that has good drainage.
Next dig a hole as large as 18 inches deep and 12- 15 inches wide for each clematis that you are planting. When planting two or three clematis together, enlarge the circumference of the hole by 3 inches for each additional plant. Loosen the soil on the sides and bottom of the planting hole. Fill the hole with water to check the drainage, it should drain slowly but steadily. This helps hydrate the area around the planting hole in addition to allowing you to check the drainage. If your clematis plants are densely rooted, soak the root ball so that you can gently tease the outer roots loose, which helps them establish faster.
Fill the bottom of the hole with your amended soil mixture, and measure the remaining distance so that when you place the clematis ( type 2 and 3) in the hole, spreading the roots out like you would in planting a rose, and fill the soil in around it, they will be planted 2 to 4 inches deeper than they were planted at in the container. For type 1 clematis, plant to the depth of the container the plant was at.
Place your clematis in the hole on a slight angle with the stems going toward the direction you want it to grow in. this is important as the angle of the crown will help the plant produce new stems and eventually new crowns.
Backfill the soil, pinching off the leaves on the stem that will be covered with soil with the new depth you are planting it in.
Water the plant well, and prune off some top growth of the plant ( see pruning how to)
Soil rich with organic matter and chunky grit such as sharp gravel or horticultural sand is the optimum outdoor planting medium because immature clematis roots find it easier to reach out and grow. Whereas dense soils like clay or rocky soils don’t allow the roots much space to take hold. Native soil that is sandy, as well as clay based soils that are amended, are perfect for growing clematis.
For garden soil that is less than optimum, amend your soil to create a better planting medium.
Clematis tolerate a range of Ph and are quite adaptable to a variety of soil types.
For planting outdoors, amendments for your native soil include: proprietary bagged compost for flower gardens, leaf-mould, decomposed grass clippings, sharp gravel or sand, oyster shell ( sold at feed stores as poultry grit in many areas), composed pine fines or mushroom compost.
For planting in containers, amendments for traditional bagged ‘potting soil’ include composted pine fines, oyster shell, extra perlite, and bagged compost for flower gardens. Alternate bullet point, For planting in containers, use a proprietary bagged planting mix that lists Canadian peat as the first ingredient.
Learn about fertilizing your clematis