‘Striking’ a cutting is essentially placing a section of plant stem in some compost and allowing it to root. It takes advantage of the function of plant nodes as growth points. Nodes are the points on a stem where the buds, leaves, and branching twigs originate. When the node is above ground it will produce leaves or stems, but when it is in soil it will produce roots. Here we will explore ways to maximise your chances of success.
Step 1: Remove the cutting
Remove your cutting from the stock plant making a straight cut below the node. Choose a cutting from the ‘stock’ plant that is 7–15cm long, without flower buds. You may need to use a knife and cutting board to ensure that you have a clean cut at the base of the stem, or to produce several cuttings from one stem.
Step 2: Remove leaves
Remove all the leaves from the lower half of the cutting. The ratio of leaf to stem can be difficult to judge, so if it is your first time try some different ratios and see which succeed the best. The leaves that you leave on will enable the plant to photosynthesise and feed the new root growth, to make so that it becomes a viable plant. If there is too much leaf left on, the plant will transpire (lose water) faster. With larger leaved plants like hydrangea, you may want to retain only one leaf and even this may need to be cut in half to reduce water loss.
Step 3: Compost
Create a 50/50 mix of compost and sand/perlite. This provides a well drained growing medium for your cuttings, and also support. Your cutting has no roots to support it physically or nutritionally at this stage. The growing medium needs to provide water to the cut surface at the base of the stem. Fill your pots with the mix.
Step 4: Plant the cuttings
Place your cuttings around the edge of the pot, using a dibber to create a hole first so that the base of the stem isn’t damaged in the planting process. They should be planted 2-4cm deep. Where the lower leaves have been removed, beneath the soil, roots will form. Space the cuttings so they do not touch each other. Leaves should be at least 1cm clear of compost.
Cuttings are traditionally planted close to the edge of the pot, the idea being that roots tend to divide when they reach a boundary. You may want to dip the base of each stem with hormone rooting powder before planting. This is not essential, but may speed up the rooting process by adding more auxins to the rooting area.
Step 5: Water and label with date
Place four canes around the edge of the pot to create a frame above the height of the cuttings and put a polythene bag over the top of these. Use an elastic band to hold the base of the bag on tight to the pot.
Step 6: Taking care of your plant
Put your pot in a bright area, but not in direct sunlight. Remove your bag often to allow air to the cuttings. Ensure that the growing medium stays moist. The cutting is extremely vulnerable and until it has produced roots it has no ability to be resilient. This means it is entirely dependant on us to meet its needs.
Achieving this is a kind of juggling act in which we need to make sure the cuttings get adequate moisture but are not waterlogged – leading to rotting of the buried stem. Also that they have sufficient leaf area to produce food for the plant but not so much that water loss becomes a problem. And that the plant has sufficient light but not so much that is liable to scorching.
Step 7: Checking on your plant
To check if cuttings have rooted, gently tug one of the leaves. If the plant lifts easily it probably hasn’t rooted…yet. You could try giving it a few more weeks if the cutting appears healthy. The time taken for roots to form varies from plant to plant but is generally 3-6 weeks. If you have chosen smaller pots for your cuttings you may be able to see roots growing through the drainage holes in the base. Successfully rooted cuttings can be potted on into a compost suitable for the type of plant.