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planting extra tips

How to grow Clematis successfully

Below you will find advice on growing Clematis. Just click on a title to expand/collapse the details

  • DO NOT LEAVE IN SMALL POTS. This is to wait for a mishap.
  • If plants wilt; cut back below wilting point and don't dig it up for at least 3 months. Clematis are semi-herbaceous so the root will survive 1-2 years without any top growth. If it is not shooting again after this time, then take your complaint to the supplier.

  • It is always a good idea to prune Clematis back to 1 pair of buds above ground level when planting in spring or summer. It is wise to keep the shoot below 1.5 metres for its first and second year.

  • When planting in pots, use at least a 20 litre pot and use a bark-based potting mix with slow release fertilizer (boosted occasionally with a spoonful of "Nitrophoska Blue Extra"). Do not use water-holding gel!

  • When purchasing smaller plants during spring it is advisable to grow them in a 2.5-3.5 litre container for the first season.


It is a wide spread assumption that Clematis need Lime. Clematis will grow equally well in peat with a pH 4 as in limestone pH 9.

All plants use calcium. Calcium is used in plants to strengthen the cell walls, when readily available it will strengthen the stems of your Clematis and help it to resist stem wilt.

Now, where can we get a high calcium supply without raising the pH level? The answer is Natural Gypsum!

Gypsum is more than 5 times as soluble as lime and 3 times as soluble as quick lime. It doesn't change the pH level and it doesn't burn like lime.

Lime is calcium carbonate and gypsum is calcium sulphate. Coarse gypsum will work as a slow release calcium supply and is therefore preferred for planting of perennials, shrubs, and trees.


Trichoderma is a good help in protecting plants against Clematis stem wilt. We have used it in all our potting mixes since 1998.

There are two products we recommend using for Clematis in the home garden:
  1. "Trichopel" (Gro-Max root mate) – to be incorporated in the soil/potting mix
  2. "Trichoflow" – to be watered or sprayed over plants and into soil.
"Trichoflow" (Gro-Max plant mate): 50 grams to 20 litres of water. You can mix 1 tsp. (approx. 4 tsp. in a bag) with 5 litres of water, and water over plants and ground and repeat every 4-6 weeks until used. The leftovers in the bag must be sealed and kept in the fridge.

Clematis stem wilt rarely kills the whole plant. It will mostly only kill a single stem and causes more worry for people than it does the Clematis.

"Gro-Max plant mate" is our preferred choice.



Can be done anytime!
In any case, they need water during the summer otherwise they will become dormant and young plants can die or will be retarded. When sufficient water and temperature is available, they will start growing again. Ensuring water will reach the root zone is paramount! Use a piece of drainpipe or a bottomless plastic bottle to water through.

Planting recommendation is for well drained soil 50cm deep.
  1. Use a strong cane to lead shoots to climbing support.
  2. Climbing support on wall or tree-trunk.
  3. Small plant to shade base of Clematis.
  4. Clematis Group "A": Plant with top level of rootball 5 cm deep.
    Clematis Group "B" & "C": Plant with top level of rootball 15 cm deep.
  5. Mix of soil and good compost, plus bonemeal or slow release fertilizer.
  6. Garden compost or well rotted manure (mushroom compost) 10 cm.
  7. Optional plastic pipe for watering (so water will reach root zone)
Note: remember to tie cane to a climbing support. Plant at least 30 cm from house walls.


1. Start digging a hole approx. 50 x 50 cm and 50 cm deep. Be sure that the planting hole is well drained and will not collect water to avoid the plant getting waterlogged.
2. If planting along a house wall, then dig a hole along the wall at least 1 meter long, 35 cm wide, 50 cm deep, and at least 30 cm from the wall.
3. Next place manure in the bottom of the hole and then fill with compost soil mix to the height where the bottom of the Clematis is going to sit.
4. Place plant with PB (plastic bag) in the hole and then cut the PB down the sides in 4 or 5 places after it has been placed in the hole. Fold the bag’s sides down and then bury the bag. Don't try to take the PB off or you could break the stem and lose the plant!
5. If the plant is short stemmed, it may be necessary to leave the hole only partially filled in and then fill it as the plant grows.
6. When planted deep, Clematis will sprout again. It is rarely they will die from wilt! In our opinion, PB's (plastic bags) for Clematis, when handled in the right way, are superior compared to hard pots. It is near impossible to get Clematis out of a hard pot without breaking it and then lose it to Clematis wilt, if it is not cut back to below the breaking point.
7. It is essential to water the plant during establishment. Ensure the water reaches the roots. Partly bury a bottomless 2 litre plastic bottle and water through it.


Size variation:
Clematis flowers vary in size during the season, are depending on nutrients, water, and temperature. During hot weather, the flowers develop faster and are smaller than in cooler weather.

Multiple flushes of flowers:
Getting more flowers from your Clematis hybrids is accomplished by pruning just like floribunda roses – two to five flushes in a season can be accomplished. Prune 2/3 of the growth when flush is finished and feed with a handful "Nitrophoska Blue Extra" and keep watered. During spring, 8 weeks till next flush. During summer, it’s approx. 6 weeks.


Do not prune between late February and mid July!

My recommendation when growing montanas on fences and other places where you don't want a crow's nest, is to prune when the Clematis has finished its main flowering. They are pruned back to 1 or 2 pair of buds on the side shoot (not the main framework), much in the same way grape vines are pruned. This will give you a strong framework and a nice plant.

Once pruned, give it a good feed: compost, manure, or fertilizer. A little corrective snipping will be needed on the strongest growing stems. Lastly, tie the vines to a support, so they do not blow down.


July – August: cut back to 30 cm, 10mm above a pair of buds (node) and lead new shoots horizontally to help make a base framework.


Group A Clematis:
  • montanas and other spring only flowering varieties.
  • Flowers appear on short flower stalks directly from a leaf axil bud; generally from previous season's growth.
  • After flowering, new growth is produced, which in turn will produce next spring flowering.
Pruning Group A:
  • After flowering, cut back to one metre. In subsequent years, cut out weak and dead stems.
Group B Clematis:
  • Most larger than 10 cm across, spring and autumn flowering hybrids like 'Nelly Moser'.
  • Flowers on previous season's wood at first and later on current season's growth. The true double-flowering ones (like 'Kiri Te Kanawa') produce the most filled flowers on previous season’s wood. Those that only produce double flowers on previous season’s wood and single flowers on current season’s wood, will NOT produce double flowers in the milder areas. This includes varieties like Cl. 'Proteus', 'Vyvyan Pennell' and 'Patricia Ann Fretwell' and many more.
Pruning Group B:
  • July – August: cut back to approx. 1 metre above base. In subsequent years, cut all stems back to a pair of buds.
  • When growing this group in a mild and wet climate they tend to get "the flu" during the winter.
  • 95% of this group benefit from hard pruning like group C. This will delay the flowering a little. The plants will be much healthier with many more flowers and nice lush foliage.
  • Don't winter hardprune Cl. 'W.E.Gladstone' (dislikes it), 'Sir Garnet Wolseley', 'Edouard Desfosse', 'Etoile de Paris' (loses a flush), and 'Mrs. George Jackman' (long delay before flowering).
Group C Clematis:
  • viticellas, texensis, and other late flowering hybrids like 'Jackmani'.
  • Smaller flowers not more than 10 cm across and generally produced in abundance during early summer and again in autumn.
  • Flowering on current season’s growth only. Previous flowering wood is dead and will not sprout again. All new shoots from below old flowering wood.
Pruning Group C:
  • July - August. Second year and subsequent years reduce all stems to just above previous season’s growth, as close down to ground level as possible or within 75 cm of base.
  • When climbing in larger trees, the pruning should be adjusted accordingly. Group C may need a 2 metre stem to get into the first branches.


Mildew is a fungus that might affect your Clematis. It is necessary for the texensis to be pruned hard during winter to avoid mildew, as the spore over-winter in the old wood and dead leaves, and will be activated by rain in the spring when the temperature becomes ideal for the spore to germinate (late September- early October when night temp. goes above 12°C). It is seldom a problem until late in the season and not a problem at all if there is good air circulation.

If mildew is noticed in its early stages, it can easily be controlled by many different fungicides which are readily available. If the plant is badly affected, prune hard and spray a protective as new growth emerges.

We recommend "Sunspray" or "Excell" spraying oil (as summer oil) in a 1:100 = 10ml per litre water – it's efficient and low risk. Concentration can be lifted to 2:100 = 20ml per litre of water.

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