I might be to late in the game to offer advice but have you heard of ezumbrella dot com (preferred concepts)? Mono-line umbrella program with $5,10,25 and 50MM limits. Ratable online, if there are no red flags you'll get a bindable quote immediately. If it gets referred they're really responsive. Their pricing was tightening several years ago but they're a great option.
I know they'll do landscapers but may have a problem with snow removal depending on who they do it for and how much of their sales are generated from it...maybe 25%...it's been years since looking at their u/w guidelines..snow removal is always a grey area in the mid-atlantic region though, considering the variance in snow fall from year to year. Unless they removed them, their u/w guidelines are available right on their site.
A slight caveat is that they don't deviate from the limits they offer (so they wouldn't do $6M, would have to do $5 or $10M) and full payment is due within 30 days of binding or you'll have to PF. Their quotes have been the deciding factor in winning some accounts between the limits and rates they'll offer so worth a look.