Propagating and dividing marginal plants
If you have ever divided up herbaceous plants on dry land then you will be familiar with the operation of dividing up the mass of rhizomes, tubers or stolons with two garden forks back to back. Alternatively, there is the gentle teasing apart by hand or the brutal attack with spade and knife to divide the lively new growth on the outside of the clump from the tangled choked up mass in the centre.
Very often just hauling the clump of plant growth onto dry land can the most difficult part of the operation.)
Most marginal plants respond vigorously to either treatment. In fact bear this in mind if you feel tempted to mix them by planting different types in the same container. They will soon run all over each other and one will become the dominant at the expense of the others. (See also RE-PLANTING WATER GARDEN PLANTS) Vigour and the ability to spread by seed and root run are all in plenty in the marginal plant world.
The spread and vigour of this greater spearwort, Ranunculus lingua var. grandiflora, is all too apparent if you know that this huge clump sprang from 6 tiny plants planted in baskets only a year before.)
But some of them the more innocuous looking species get the "upper petiole", so to speak, from root exudes. These are chemical growth inhibitors that decrease the competition from surrounding water plants: another good excuse not to put one type of plant in with another.
Marginal plants in contoured planting baskets ready for placing round a pond. Apparently marsh marigolds produces an exude from their roots that inhibits the growth of nearby competing plants. In this case, it would be interesting to see how the marsh marigold on the right in the bottom left basket copes with the likes of the yellow flag and the Lobelia.
If in doubt as to what will survive as a plant when dividing up an old clump, take what seems to be a substantial proportion of the most recent re-growth and replant it at the same level in the soil that it was at previously. Replant it in the same type of compost that you would use for lilies - see above.
Dividing a portion of a clump of Cyperus longus. Even in the autumn it is obvious it easy to see which shoots with live roots will make good plants.
Top dress with gravel in the same way, making sure any fresh emergent shoots are not buried under the gravel and compost and can get a good look at the sun.
PLACING marginal plants in their baskets in the pond is a relatively easy operation done from the bank. As a general rule, the plants will all be quite happy if the water is just over the edge of the planting basket by little more than half an inch. You may need to raise the baskets up on flat stones. But perhaps if there are just a few baskets that sit a little too deeply in the water then could reserve these for the Alisma plantago (Plantain), Calla palustris(Bogbean),Orontium aquaticum(Golden Club), Pontederia cordata (Pickerel), Sagittaria sagittifolia(Arrowhead) and Typha latifolia (Reed Mace). All these plants can be submerged from 2-4ins. Zantedeschia aethiopica (Arum Lily) appreciates a depth of 6"-9".
Marginal plants
Nowadays it is not necessary to line the planting baskets with hessian liners unless there are koi in the pool. Use a good heavy chemical free loam to fill the basket to the brim.
1. Make a space for the plant and drop it into place and push the soil in around it.
4. The basket is topped off with peagravel to hold the soil in place.
5. The marginal baskets are placed on the shelf round the edge of the pool; their height is adjusted with bricks so that the level of the baskets is just below the surface of the water. This seems to do for virtually all of the marginal plants.