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Ponds & water features

Here are the answers to some commonly asked gardening questions about ponds and water features.

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Could you please advise on our newly built pond - it is now nearly completed and we need to know what and when to put plants in the pond. Our pond is 16ft x 6ft x 2 ft deep with a waterfall, running stream and a holding pond at the top. We need info on Hostas in particular and other water plants that you may suggest.

I would leave planting the pond until spring. The water needs time to settle and for dissolved nutrients to dissipate. Also, you won't be able to buy many plants at this time of the year.

In spring, go out and buy oxygenating plants first - you'll need one bunch for every 2 sq ft of water surface. After another two weeks you can start introducing the marginal and other aquatic plants.

Hostas aren't suitable as pond plants - they are planted in the soil around the outside of the pond. There are literally dozens of plants to choose from, so I suggest you get a good book on the subject. The Rock and Water Garden Expert by Dr DG Hessayon is excellent and only costs a fiver.

My particular problem relates to blanket weed in a small tub feature.

In your situation, blanket weed will be a problem because the tub isn't deep enough, there's too much light hitting the water and because the temperature of the water increases.

Try shading the water surface a bit more; water lilies and floating aquatics will help. Or move the tub somewhere where it doesn't get so much direct sun in summer.

Lots of dissolved nutrients in the water will also encourage growth, so feed plants to a minimum (and fish if there are any in there).

If this doesn't help, you could add a few handfuls of barley straw (available from aquatic stockists) which causes the blanket weed to flocculate and drop to the bottom. If this doesn't work there are more powerful chemical agents which should work; these are also available from aquatic stockists.

I have a water feature made up of eight ponds, seven feeding the largest by gravity. The pump feeds water back to the top pond continuously so that the water is well oxygenated. In the ponds I have put in what I bought as water hyacinth. This is a floating plant but does not look like Eichhornia crassipes as illustrated in the RHS Plant Encyclopedia but more like Salvinia auriculata. Last year I lost the plants as I was unaware that they were not frost hardy. This year I have put them in plastic buckets in tap water in the greenhouse which is thermostatically controlled to a minimum of 50F. The plants after a week are turning yellow with black patches and I fear I am going to lose them. Can you please advise how I can save them.

There are a couple of things to say.

First, these plants are not easy to overwinter anyway!

I'd use pond water rather than tap water - there may be too many chemicals in the tap water.

These plants like higher light levels than we are experiencing at the moment.

It may just be a natural thing - losing some of the older leaves at this time of year is natural.

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Garden answers

Ponds & water features

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