Strategies to protect infrequently watered tomato plants

Question

I have a field out of town, where I can grow vegetables, however it is too far away for me to water daily, I can do every 3 days max.

What are some good strategies to protect tomatoes from the direct sun and evaporation?

Would a plastic, semi transparent plastic cover help? Or should I rather only cover them from one side, so they can still get direct sun light the rest of the day?

What about mixing some vermiculite into the earth to hold moisture for longer? Or maybe a plastic cover around the plant, to keep the earth moist? Maybe one of these cone things?

My plants are located here: https://www.google.com/maps?q=orth+an+der+donau&gs_lcp=CgZwc3ktYWIQAzICCAAyAggAMgIIADICCCYyBggAEBYQHjIGCAAQFhAeMgYIABAWEB4yBggAEBYQHjIGCAAQFhAeMgYIABAWEB46BAghEBVQ3lxY3lxg7l9oAHAAeACAAYcBiAHAA5IBAzAuNJgBAKABAaoBB2d3cy13aXo&uact=5&um=1&ie=UTF-8&sa=X&ved=2ahUKEwj4mrPdvoTpAhUPsKQKHU5MDQkQ_AUoAXoECHQQAw

Right now its fairly dry, raining about once a week, RH mostly at about 30%-40%. There are times when it rains more frequently than that. Right now its on avg. about 20°C, but it will get to about 30 during the summer. I can water the plants every 3 days.

Answer 1

First, I mulch my tomatoes to prevent moisture loss from the soil, to help prevent various blights/fungi, and to keep down weeds. If you don't mulch, I strongly recommend that you do so. I use a byproduct from the chocolate industry - cocoa bean hulls - because they break down over the winter. Straw, pine needles, or anything else that has a short "groundlife" would work fine.

If you mulch the plants, then I don't think you have anything to worry about. I compared your average rainfall to my own area's average rainfall so that I can give you fairly accurate advice.

Tomatoes are native to hot, relatively dry areas of North America, so I don't water my tomatoes at all (once they've established themselves after transplant), except during periods of drought. I define drought as hot, sunny, and no rain for 7 days (in July) or 10 days (in August) - the difference in days is to account for larger root systems in late summer.

BUT

My area gets roughly twice the summer rainfall that your region gets. And, I suspect you're in a hilly/mountainous area whereas I'm in a glacial outwash plain. Given these differences (especially the rainfall), I'd recommend that you water your mulched tomatoes no more than once every three or four days - and that's only if they have not received 2-3cm of rain during that time. Before watering, check the ground under the mulch and then don't water, of course, if it's already moist.

Answer 2

Plant them deep, when you put them in, only leave the top 4-6 leaves above the ground.

Get starts which are the tallest. We usually pick those that others would leave behind because they look too leggy.

Make sure your soil has some clay and organic material mixed in.

When you do water, water deeply enough to soak the whole root system.

Make sure the water soaks in and does not run off.

At the same time since you cannot be there often you should make it so that your holes that the tomato plants are put in will hold enough water to soak the root system, but that too much can run over the top and away.