Contrary to popular belief it is perfectly possible to grow some varieties of these beautiful aquatic plants in at least the southern counties of the United Kingdom. We have been growing them outside here in East Anglia totally unprotected from frost since 1998. We experimented with different varieties until we found three which grow in our climate year after year. All tubers are our own, grown on the premises here; we do not sell imported lotus, which can be difficult to establish.
They do however need specific growing conditions in order to succeed. The difficulty with growing lotuses in the UK is our lack of summer heat. Lotuses have no problem with winter cold, but they need a period of high temperatures in order to bloom and lay down tubers for the following year. So, if you are north of a line stretching from the Severn estuary to The Wash, if you are growing right on the coast, or if you are growing at high altitude, then they will probably not get enough summer warmth to bloom and return the next year (although this will depend on the conditions in your own particular garden). If your garden is within this geographical area, then the right spot for them is somewhere very sunny and warm (at least 6 hours direct sunlight per day from April to late September) and sheltered, so that the heat is retained and the foliage is not damaged by strong winds - rather like the rules for growing tomatoes outdoors. If you like lotuses but your garden doesn't have anywhere suitable or you're too far north, you can grow them in an unheated polytunnel or greenhouse - they love the high summer temperatures these produce. You can also grow them in a polytunnel or greenhouse for most of the year, to benefit from the higher temperatures, and then bring them outside at the height of summer. We have not done this ourselves, but it was done by an RHS garden when growing our lotuses in the north of England.
The tubers should always be planted in round containers, as the growing points may be damaged by growing into corners, and this damage can cause the plant to die. For the same reason, do not use open mesh baskets such as traditional aquatic baskets, as the growing points can get stuck in the holes in them and die - use solid containers. The growing container also needs to be large - we would recommend something at least 45 - 90cm (18 - 36 inches) in diameter and at least 15cm (6 inches) deep. Black containers are best, as these absorb sunlight and warm up the plants more quickly. Because of these requirements, many people choose to plant their lotuses straight into very large round water-tight pots which in effect become a small pond in their own right. This also enables you to pick the exact perfect spot in the garden for them and, particularly if you are in a cooler location, means they will warm up more during the day than if they were in a traditional pond.
The growing points on lotus plants, where the shoots emerge, are extremely fragile. If these get damaged they will not re-sprout and if none of the growing points can sprout the plant will die, so please unwrap and handle your lotus with great care at all times. Plant the lotus in heavy clay loam or, if this is not available, special aquatic soil. Place the tuber horizontally just under the soil - the tuber itself should be buried (otherwise it will float) but the shoots will be poking out. Then place it so that there is 5cm (2 inches) of water over the soil and no more - the plants need as much sun and warmth as possible in order to put on sufficient growth to make tubers for next year, and this is only achieved if they are just under the water surface. When you see emergent leaves, carefully push a couple of slow-release fertiliser tablets into the soil under the tuber. Flowers appear August to September (although this may not happen in the first year). During the winter leave the tuber where it is, below the frost line, and it will be fine. It does not need extra protection from frost nor to come into a greenhouse or garage.
Please note there is only a very short window to ship lotus tubers - usually two or three weeks somewhere between late March to late April/early May, depending on the weather. This is because a tuber has to be visibly sprouting before it can be sold (to confirm that it is a living tuber with growing points) but as the shoots grow further the plant becomes simply too delicate to dig up and post.
We usually have many more people wanting lotuses than we can supply; if you would like to buy one we would recommend putting yourself on the 'notification' list by clicking the link on each plant's page. We will offer plants first to those people who have been waiting on the notification list for the longest. Our lotus waiting lists keep increasing - the current waiting time is two years.