The subject today is irrigation: this is a pressing issue since we have had so little rain this month. Typically in our Southeast Pennsylvania region we get one inch of rain per week. For the last three weeks the amount of rainfall has not even amounted to one inch!
How can you tell whether a rain event has benefited your garden? The best trick to gauge this is to check whether the area underneath parked cars is wet after a rain; this would mean that the rainfall has at least amounted to 3/4-1 inch of rain. If indeed the area underneath parked cars is dry after a rain, this event has not benefited your garden and you still need to water that day.
We need to distinguish between the establishing phase and maintenance phase of irrigation for your direct seeded and transplanted crops. Within the first week of either direct seeded or transplanted crops, daily watering will be necessary.
Watering The First Week: When “watering in” your transplants, apply a half gallon of water per plant. Puddling around plants is only allowed on the day of transplanting, when you have created a dish like area around the transplanted crops so a good soaking can be achieved. Beginning on the second day, apply water in a broadcasting, fanning style with a hose or watering can all across the raised bed, always going back and forth until the water has actually penetrated down to the roots of your plants, or just below the line where you have placed your seeds. This watering schedule for the establishing phase should continue, every day, for one week. Only skip this watering on days when you have had the appropriate soaking rain event mentioned above.
Watering After The First Week: After the initial week, once seeds have germinated and transplants have taken, you can think of irrigation as a biweekly maintenance task. During this time you apply roughly a 1/4 inch of water, emulating our meteorological patterns. Here is an interesting calculation:
When you hear in the news that we have had one inch of rain, you can imagine this to be an even coverage of one inch of water, or 30 gallons, on your raised garden bed; something like a deep puddle which is constantly infiltrating into the soil. How many gallons of water does that equal per bed? To determine the amount of cubic inches per bed (12′ x 12′ x 4′ x 12″=6912 cubic inches), you convert the number of cubic inches of water into gallons. This is done by dividing 6912 by 231, which equals roughly 30 gallons of water. Given that calculation the maintenance watering of 2 medium sized watering cans per bed, twice a week, actually only amounts to 10 gallons of water, or a third of an inch, which is the bare minimum to support your crops. During dry times like this, to emulate a rain event of one inch per week, you should try to double the quantity of water you apply during each watering.
The average water requirements for vegetable crops is 20 inches of water per growing period; this amounts to between 1 1/2-2 inches of rain per week. In watering cans, this is 18 cans per bed- this is to equal to 1 1/2 inches per week. That means three days of watering with your watering can, six cans per bed per watering day. Yes, that is a lot of trips to and from the garden beds with a heavy watering can, but your plants will look for you anxiously to give them a much needed drink.
An irrigation system for your garden is more effective than hand watering. Irrigation systems such as the fan and overhead sprinklers can put out 10 gallons of water per minute; in one hour they apply roughly an inch of water. Generally, drip tape or soaker hoses are more efficient because they apply on the row, or between the row, where crops are planted, whereas overhead sprinklers wet the entire area and pathways, and have a slight compacting effect on soil. They can promote the growth of weeds in the aisles, but they are less expensive. The loss of water due to evaporation with sprinklers is higher, but an advantage is being able to freely cultivating without having to move the drip tape or soaker hose, and as stated above they are less expensive.
Drip tape irrigation applies the required amount of water within relatively brief water sets, twice a week in comparison to hand watering or sprinkler systems. Drip systems are the best irrigation systems, although they are the most costly, because there is no wasted water. Irrigation can be hard to do accurately, and also physically, with watering cans; which is why people often eventually install an irrigation system in the garden.
Our ancestors often relied only upon rain for the garden which meant that gardens would sometimes fail when conditions were extremely dry, especially in the establishing phase. Irrigation has been an issue as long as people have been raising food. We must always remember how fortunate we are to have water at our fingertips.
For those who water with watering can, your dedication to watering is heroic! Thank you!
Remember to cultivate your garden beds, especially in these dry times, and sing to your plants!