One deep watering per week is much better than short waterings more frequently.

Tomatoes need less watering than the rest... each plant has different needs. If you water tomatoes too much you will probably end up with blossom end rot... where, if you actually get fruit, they will be rotten on the bottom. In 100º temps, I water my tomatoes DEEPLY every other day.. in cooler weather.. less often, in 80º temps maybe once every 4-5 days. Green peppers can take a little more watering, in 80º temps, I'd water them deeply every 3 days... radishes and peas, I can't grow in the summer, so I don't know, I'd suspect they could be watered every other day in 80º weather. If you get a lot of summer rain, I would take account for that as well.

You could try in the vegetable forum for gardeners in your area, you would get the best watering info from someone in your area.

I prefer soaker hoses and use only this method to water. It varies with the vegetables that are grown. Things like melons and cucumbers need a LOT of water, so I usually water these everyt day or two. The rest can get waterings about every 5-6 days, unless it rains for a few hours. Tomatoes and peppers usually don't need too much waterings, and neither do peas and beans. Its also dependent on the heat of the day, the kind of soil and many other variables that can factor in as to the amount of watering. A soaker hose helps to reduce diseases on the leaves of some plants. I have b=nearby blueberry bushes that see no waterings at all, as they have a natral oak leaf mulch that they grow in. This acts like a nice moisture barrier. The rest of my gardn has a black fabric mulch that alos helps to hold in moisture and reduces weeds.

Definately need to make a change in that watering timing. When talking about how much water a veggy garden needs the rule of thumb is 2" per week - preferably in the form of a slow, steady, warm rain. The garden will need more in high tempuratures, less when it is cooler. I find the best indicator is to check for surface moisture. You want the top 2 inches to get dry, but no more than that.

In any case it would be much, much better to run that system for 1 hour every 4 days - rather than every 4 hours. frequent, light watering makes for shallow, weak roots. Water deep and allow the top to dry a couple of inches down between waterings, for strong, hardy roots. Also, if the garden is always wet, you are just begging for mildews and fungi to take up residence.

Also take into account WHEN you water. If you water your plants in full sunlight, then the water is more likely to evaporate then if you water in the evening.

I use the drip system. How often should I water my vegetable plants. Tomatoes, cucumber, eggplant, asparagus,
green onions, bell peppers, zuchini etc.

Some plants are composed of up to 95 percent water. Water is vital from the moment seeds are sown through sprouting to the end of the growing season. Plants need water for cell division, cell enlargement, and even for holding themselves up. If the cells don't have enough water in them, the result is a wilted plant. Water is essential, along with light and carbon dioxide, for producing the sugars that provide the plant with energy for growth. It also dissolves fertilizers and carries nutrients to the different parts of the plant.

Here is a link that might be useful: howstuffworks