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Pruning Clematis, Pruning Groups and How to Plant
Last Updated on January 22, 2020 by John
Planting your Clematis
This clematis planting guide is designed for planting clematis grown in 2 litre pots or larger.
Where to start
First of all, you will need to dig a hole of approximately 15” (38cm) in diameter and about the same 15 inches in depth. After this, you will need to break up the soil which is at the bottom of the hole and mix compost with a small handful of bone meal (bone meal encourages the plant’s root growth) through it.
Clematis generally need to be planted deeper than most garden plants so that the root ball is underneath the soil by about 5” (13cm). Firstly, soak the root ball of the plant in water for about 20 minutes and then you will need to remove all the leaves from the bottom 5 inches of the plant so that only the bare stem is left. Now you need to plant the clematis so that the top of the root ball is 5” (13cm) below ground and back-fill with a mixture of topsoil and good quality compost. Finally, top-dress with a good general fertiliser such as osmocote.
You can cut a young new plant back by about 50% if you prefer as this will encourage new growth.
Clematis are planted for flowering in the following year, so don’t expect too much growth within the first year, although many do put on plenty of growth and produce plenty of flowers.
Growing clematis in pots
If planting into a pot the same steps as above apply, but add 2 inches of gravel to the bottom of the pot to help with drainage and add around four slow-release fertilizer tablets to the compost when planting. Finally, add a 1-inch layer of bark or stone chipping to the surface of the soil to help retain moisture and help prevent weed growth.
Clematis benefit well from a good feeding and it encourages good blooms of flowers and excellent growth. From mid-spring, feed with a good feed about twice a week, following the manufacturer instructions until just before flowering. After flowering, feed again until mid-autumn to encourage good growth and flowers again.
A good feed to use is tomato feed which is available cheap from most garden centres and supermarkets and is high in potash so encourages flowering. Specialist clematis feed can also be purchased.
The following instructions are ideal for larger clematis in 2/3 litre pots. If you have purchased a smaller plant in a 7cm pot then the same applies but you may want to just plant the root ball just below the surface about 1-2” unless the clematis is approximately 30cm tall (then you can plant the clematis about 5” below the soil as stated above). Many clematis in 7cm pots have all ready been pruned back to create bushy plants.
The first main rule for pruning is; “if it flowers before June then do not prune”.
Group 1 – No Pruning
These clematis flowers upon the previous season’s growth and flower earlier in the season. These include Montana’s, alpines and macropetalas as well as evergreen varieties. They only need pruning to remove any dead, weak or diseased growth in late May/June. If you have a clematis in this group which is too big or has grown out of control, then you can prune them back hard down to a couple of feet if needed.
Group 2 – Optional Pruning
Clematis in this group include semi-doubles, doubles, early and large flowering hybrids and usually flower in May/June and September. These can be cut back by about halfway in July and then in February/March dead or weak stems can be removed.
Group 3 – Hard Pruning
Viticellas, herbaceous, species and late large flowered varieties all fall into this group. They need to be pruned back hard in February/March to two strong leaf buds which is usually around 1ft (30cm) from the ground. If these varieties are not pruned back hard it is likely that the base of the plant will become bare.