To Mulch, or not to Mulch?
In the spring when we plant the weather is cool with higher humidity. We usually get some rain, even here in So. Cal.
The common wisdom is to put down a layer of mulch at that time.
We don't need it, but we just do it because we're "supposed to."
Our biggest pest problems, slugs, earwigs and pill bugs, love us for our labor and our consideration of their needs. We provide a haven and breeding ground for them. They'll devour our seedlings as they sprout and give us problems throughout the year.
I've had to take almost no pest control measures at all for the past few years. I don't create that breeding ground in the first place. Later, when the weather warms and the humidity drops, mulching is a good idea for holding moisture in the soil--if I can get to the soil. Most of my plants are so spread out and enormous by then that I can't put down mulch without damaging the plants. I put it where I can, but mostly I can't get to the soil.
Where I used to have an ongoing battle with all my obnoxious little friends, it's now rare to see one. I don't use any more water than I did when I was providing a protective haven for my worst enemies.
Keep your bed surfaces clear of debris and mulch in the early growing season. You'll stop most of your pest problems before they start.

Tomato Preparation

I planted these legumes in November. They're a mix of woolypod and purple vetch, Bio Master Peas, Bell Beans, and Cayuse Oat seeds. Just before that, I spread fish bone meal, kelp meal and guano over the bed before turning the soil.

After I turned the soil, I broadcast-ed the seeds, raked them a bit to try to cover most of them, and tried to keep the surface damp for a week or so, until they set down roots. I've ignored them since then.

On 13 March, I chopped them with my hedge trimmer, spread 150 lbs. (about 2 lbs. per square foot of bed surface) of Alfalfa Meal over the top, and dug it all well into the soil.
I left the drip system on for about 5 hours, until the bed was thoroughly saturated, and covered it tightly with 6 mil. plastic sheeting,

Today, 15 Mar., 48 hrs. later, the temp of the soil is 120 F. It will easily reach and exceed 140 F. over the next few days. That will kill any possible diseases that might be in the soil.
Around the end of April, I'll remove the plastic and let the soil cool down to about 80 F. I'll turn the soil once more, and I won't find but a few traces of legumes, or anything else other than incredibly rich soil.

About the 1 of May, or a week before, I'll lay in my Tomatoes and hope for a warmer summer this year, than our record cold last summer!