Horticultural-strength vinegar (acetic acid) is very caustic and, while considered organic as a pesticide, carries a higher-than-average risk for personal safety during use. As with any non-selective herbicide, synthetic or organic, it also risks damaging any plant it comes into contact with, though admittedly such damage may be less permanent (depending on the dosage and plant type) than an accidental contamination with a systemic. The active ingredient glyphosate breaks-down into a substance of fairly low toxicity (such that table salt might actually be more harmful to the soil and plant roots in the area in the long term), and it tends to be one of the only highly-effective options for certain tenacious perennial weeds. As with other herbicides, when used responsibly and according to all label instructions, it should carry relatively little risk to the applicator and to the environment, and any known above-average risk should be stated on the product label or can be checked online on sites like the National Pesticide Information Center.

Our IPM crew, who writes for a commercial audience (nurseries, landscapers), created this write-up about acetic acid and glyphosate that might be of interest: Vinegar: An Alternative to Glyphosate?

We do not recommend mixing any herbicide with salt, nor do we suggest mixing any other combination of products unless expressly allowed by the pesticide's label. (The label is a legal document, and you can always contact the manufacturer to ask about anything on it that's unclear. What applies to one formulation may not apply to another, even if they use the same concentration of active ingredient, since the inert ingredients may differ.)

Plants with very waxy foliage, like the Lesser Celandine, may be more challenging to effectively treat with an herbicide in general, regardless of active ingredient. Still, products exist that can be mixed into the solution to promote adherence to the leaves so the chemical can be absorbed before the liquid drips off. These are called either surfactants, spreader-stickers, or adjuvants, and they are often available alongside pesticides in garden centers because the two are commonly used together. Some formulations of pesticides/herbicides already include a surfactant, which is why you'll need to check the label to be certain it can be added. A separate set of directions will be provided on the label of the surfactant itself. Another optional addition intended for use with a variety of herbicides is the dye used to help a user remember what plants they have already treated so you don't miss some or double-dose others (and waste chemical). Here too, label information should help clear-up whether this is an included ingredient or something you can add (and what type to add so they don't interfere with herbicide function).

Lesser Celandine has a fairly narrow window of opportunity to apply systemic herbicide in spring, and we're just about at the start of it (or it sounds like you're in that zone now). Look for leaf emergence and get them treated promptly, well prior to leaf loss as they go dormant because after that point the herbicide won't  impact them. The only other recourse if you wish to reduce herbicide use is to dig up what plants you can, though expect they will return for some time until you can manage to get them all. Preventing surface water runoff from entering the property from off-site can also help since this plant's bulblets tend to spread most readily by floating around in stormwater. You can certainly take an all-encompassing approach to manually remove what you can and then spray the rest.

Japanese Stiltgrass is an annual which dies over the winter, so season-long control is the most effective when you can prevent seed germination in spring. Deer can carry their seeds about on their feet/hooves/fur, so excluding deer from the property, if possible, may go a long way to reducing reintroduction of this weed in future years. We are quickly approaching the time of year a pre-emergent would need to be applied, as Stiltgrass often germinates a couple of weeks prior to Crabgrass, which is reliant on soil temperatures. Any missed or untreated plants should be pulled up prior to late summer/autumn seed formation, but not so early in the season that they regrow and set seed later. In natural or shaded areas where Stiltgrass has been a problem, some gardeners are finding that aggressive native plants used to cover the ground have been largely able to out-compete the Stiltgrass. We don't have a full list compiled, but have heard about successes using Golden Ragwort (Packera aurea) and Orange Jewelweed (Impatiens capensis), the latter of which is an annual that reseeds eagerly.

We have information about some suppression or treatment options for the other lawn weeds on their respective web pages: Chickweed, Hairy Bittercress, Henbit, Mock Strawberry, and Spurge. The spring-blooming weeds often bloom in late summer or autumn, and only become noticeable in spring when they're large enough to flower; thus, weed prevention should begin at the end of the growing season instead. Lawn overseeding each autumn can go a long way towards improving its overall vigor and density so it can out-compete most weeds on its own. Other lawn maintenance practices like periodic soil testing (using lab services, not home test kits which are less accurate and detailed), core-aerating compacted areas, and mowing high with sharp mower blades can contribute to a more resilient and largely weed-free lawn. We can help you to interpret the results of a soil test if desired.

We applaud the removal of English Ivy and Japanese Pachysandra since they are invasive weeds, despite being popularly planted. Your options for removing what pieces resprout that remain behind are the same as for any other type of tough perennial weed: you can treat the resprouts with systemic herbicide or use repeated removal of their foliage to starve-out what root energy reserves remain. Organic herbicides like vinegar that only kill what they contact (so, foliage but no roots) and the manual removal of foliage through trimming or pulling off leaves accomplishes the same thing -- they deny the plant the chance to replenish root energy reserves via photosynthesis. Since plants use-up stored energy each time they must resprout, eventually this process will starve them and they'll die out. Being vigilant for sprouting and the prompt removal of new foliage will speed-up the process of exhausting the weeds.

Miri