Good quality compost should have plenty of humus in it and that helps retain moisture. Some bits of old broken terracotta pots at the bottom of your troughs will also help, not only with water retention but essential drainage. Don't keep your plants permanently standing in water, the compost becomes stale, waterlogged and the roots will rot. A plant wilting is not necessarily a sign of needing water. A good rule of thumb, literally, is to press your thumb onto the surface of the compost, if it comes away with some compost sticking to it then it's moist enough, if not water it. Don't forget to feed, little and often (liquid feed is easy to apply). Healthy plants are more resistant to pests and diseases.
I've been a gardener for 60 years and I still love the challenge and reward.I have my Grandfather to thank for tolerating my 'help' on his allotment ........... amazing what kids will do for a few raspberries etc.
PS Hubby is a concrete gardener and only recognises plants if they are on his plate
