While production of high yield potato crops in the home vegetable garden is achieved by watering potatoes regularly, it is maintaining a consistent soil moisture throughout the growing season that is the key factor. Water stressed plants are much more susceptible to disease and pest problems than plants that have a consistent supply.
It is good practice, in hot dry weather, to monitor the moisture content on a regular basis to see if the potato bed has sufficient moisture for good growth.
Good soil moisture for potatoes is essential for bumper crops, consistently moist is the key.
Potatoes need about 1 - 2 inches (2.5 - 5 cm) of water per week. If Mother Nature is reluctant to supply the necessary water, then some type of irrigation system is going to be required. When irrigating the crop, a few thorough night time soakings with a soak hose throughout the growing season is better than more frequent watering that just wet the surface. For best results let the water soak down a good 8 - 12 inches (20 - 30 cm)
Inconsistent watering can cause your potato tubers to produce ears and noses, become split, or have hollow hearts. This irregular growth of potato tubers usually occurs when the potato bed is allowed to dry out too much and then receives a thorough soaking.
Towards the end of the growing season when the tops are starting to turn yellow and die off, you can slow down on the watering. But, still don’t let the bed dry out completely. The potato crop, at this point, still needs to be kept moist. Harvesting in drier soil is easier and potatoes are better cured and ready for storage.
Good watering management and mulching should see your crop through the dry summer periods with a bumper crop to harvest.
It is better to use a soak hose to supply the water needed rather than overhead sprinkling when watering potatoes. Many fungal diseases thrive in the warm wet conditions that can be created by overhead sprinklers in hot weather. Soak hoses not only reduce the chances of inducing these conditions by keeping the water on the ground and not on the plant, they also reduce water wastage by delivering water where it’s needed without wasteful over spraying.
Not much to see, just the start and end of this soak hose in a single row of potatoes. The hose is laid down before the first mounding so it is buried more as the potatoes are further mounded, putting the water at the plants root system where it is needed.
The arrow points to exposed soak hose, it took a little digging to find but you can just see the exposed soak hose.
If an over head watering system is all that is available, avoid watering potatoes in the heat of the day. Either early morning before the heat of the day, or late evening after the hottest part of the day has past.
In many areas water restriction in the summer months are a fact of life. If water conservation is a key factor in what and how you are able to grow potatoes, then mulching might be the answer. The practice of mulching has a tremendous impact on the consistency of soil moisture and cannot be over emphasized. Potatoes are particularly susceptible to excessive soil temperatures and inconsistent soil moisture.
A good thick layer of organic mulch will help keep the soil both cooler and reduce moisture loss from the soil beneath it. Anything that will provide the soil with a thick mat of protection is good, used here is a mixture of straw, dried grass clippings and leaves.