Can you recommend an effective weed spray that's less toxic than Round-Up?

Don’t be afraid of roundup. Just make sure you shower right after you apply it, wear clothing that covers your skin and just do what you can to not get it on you. I’m sorry, there is no magic organic bullet. Alternatives usually are acid and iron based and will affect soil. Roundup will kill the vegetation without damaging your soil. Roundup will also kill what you apply it on while sparing what you don’t. I’m not for using it on crops we grow for consumption but, it works wonders around the yard.

There are two natural ways of doing it. Vinegar and salt, but keep in mind it will make the soil useless. But boiling water can also kill it down to the roots without ruining the soil or anything nearby if you are careful in pouring it.
Another method. One that I use is pouring a lot of water or waiting for a heavy rain to pull out the weeds by their roots with a weed puller.
I never liked round up because of two things. It ends up in our water system and you never know what animal may come in contact with it and get sick or die. Especially pets.

You can get weed and feed granules for your lawn. Brands like Scotts make them. The thicker your grass the less room for weeds to grow.

I would just cover up and spray away. You will touch or inhale a little bit of the Round-Up maybe three times a year. I wouldn’t worry about it at all, but that’s me.

Natural killers will likely kill your grass.

You can cover the area with cardboard and just leave it until the weeds are dead from lack of sun. They’ll turn into nourishing soil for plants you like better, and the cardboard will break down surprisingly quickly, too. In general, try using native plants for weed-afflicted areas because those are less fragile and more likely to succeed in claiming their space. They’ve developed protections against local pests, too. Maybe pick up some hardy ones at a plant exchange, if you have any local events like that? And the daffodils, you can dig up – or, if you’re doing the cardboard thing, just cut some daffodiil holes. For your lawn, maybe do the boiling water trick if you really can’t stand the weeds. Grass, though, is environmentally imperfect. It’s a very uniform habitat and it doesn’t allow for the diversity insects need. So, if you like butterflies and ladybugs, consider changing your lawn a little bit. One way to do this is to create little islands of wildflowers, and you could do that in the spots more likely to grow weeds. Wildflowers are fine with weeds, They grow fast, they’re pretty, they hide the weeds, and they’ll disappear in autumn. Not a long-term commitment. An alternative is to replace (parts of) the lawn with other ground-covering plants, but ones that are a bit more natural. I know clover is a popular choice, but it’s probably best to research this for your specific climate.

(It’s very wise to avoid herbicides. You can cover up, but the place you’re spraying is alive, too. We’re literally killing insects and micro-organisms that we desperately need. That poison is staying in the soil and getting absorbed by next year’s cucumbers and the hibernating amphibians. It’s going into the groundwater and getting humans sick. Nothing truly disappears. If we could stop yearning for a weed-free existence, we’d be rewarded with more meadows, more health, and happier wildlife.)

I used Round Up once, two summers ago, because I had poison ivy along the perimeters of my deck. I knew if I called a landscaper, they’d probably charge extra to take care of it because it’s poison ivy, so I bought a bottle of Round Up. I wore gloves when I applied it. It comes out in a foam so it’s very targeted – it doesn’t spray on anything other than what you aim it on. I wouldn’t use it on large portions of land, but for the border around the deck, it did the trick.

Did I feel guilty? A little but I knew if I got poison ivy, it wouldn’t be a pleasant summer so I felt I needed to do the Round Up.

I personally don’t use any herbicides. I perform the effort to manually remove unwanted weeds. Too much risk to non-targeted plants and animals. The indirect effort from flowing into watershed area or ingestion from decomposing plants are not worth it to me. Addition risk when multiple herbicides mix or herbicides mix with pesticides.
It’s just not worth it to me.

I asked my lawn guy not to use Round Up some years ago and he doesn’t. It is highly toxic to many organisms. Unfortunately, I don’t know what he is using instead but I think it was recommended by the county ag agency.

If you go to a garden center in Cal, you can probably get better information than the opinions given here.

Rototill and rototill every ten days for a month. You’ll end up with a “dust mulch” ! Continue to how or rake the area once a month.

Round Up targets an enzyme unique to plants, so it’s toxic to all plants but not so bad for animals. Still, don’t get it on you. This site says it lasts up to several months before breaking down:
https://www.evergreenseeds.com/how-long-does-it-take-for-roundup-to-break-down/

White distilled vinegar. You can buy a huge bottle, at any grocery market, for very little cost. Use an empty, rinsed dish detergent bottle, so that you can concentrate how you apply the vinegar.

In my experience, it takes a couple of days for the magic to happen. Then, after the next rainstorm, the soil will be clean and ready for replanting.

@longgone I have done RoundUp for poison ivy as well, when nothing else had any measurable affect on it, and I had to take a scorched earth approach. I use other methods for lesser weeds.

@Jeruba I would recommend calling the botany/horticulture department of a local university and asking them for advice. Some of the generic non-toxic suggestions kinda ruin the soil for same year replanting.