It is possible to be successful Growing Watercress even if you are not fortunate to have a stream at the end of your garden, as despite popular belief watercress does not have to be grown in moving water. It will grow quite happily in very moist soil or a bucket of water! It is not an actual water plant, as the roots grow in the water, but the plant grows above the water.
Planting from seed can be achieved by placing the seeds on a paper towel that has been soaked in water, place the seeds on the top and keep the paper towel moist, the seeds will germinate in approximately 10 days. Once the seedlings have germinated plant them into individual peat pots and leave them to grow for about 3 weeks, after this time they can be transplanted into the soil when the danger of frost has passed. Be careful when transplanting as the roots are quite fine and delicate. Plant approximately 15cm apart in full sun.
Watercress can be sown directly into the ground from May, as long as the site is quite damp and in the shade, and you chose the land cress variety. It will have grown sufficiently to harvest in July.
Once established mature watercress plants will send runners from the mother plant, cut the older plants back to 10cm and they will begin to grow new leaves.
If you cut the plant back to 10cm in late spring it will re-grow ready for re-harvesting in the fall.
One of the easiest ways to grow watercress is to buy a bunch at the super market and put it in a bucket of water. The water must be changed daily as watercress does not tolerate stagnant water. Put the bucket in full sun.
It is also possible to grow watercress in your pond, but remember it does not like stagnant water, so unless your pond is dirty, which the majority are, you will not have any success.
To harvest watercress simply cut the leaves just above the ground, make sure you leave the roots so that they can sprout again. The best flavored leaves are in spring and fall, the heat in summer has a tendency to deteriorate the taste.
You could also try Growing Watercress in a black polythene bag, it should work on the same principles as being grown in a bucket, the bucket seems easier to manage!