I would certainly wait until the weather is cooler.

Tell her you don't want or need a drip system, and she should plant accordingly.

Why wouldn't she want a drip irrigation system?? If the plants are being watered properly - and that is far more likely to occur with a drip system than it is if watering by hand or even a pop up sprinkler system - then you can plant any time!!

The only concern I would have is the landscaper not guaranteeing the planting - that is SOP for any landscaper worth their salt in my area and it would be a requirement I would insist on regardless of planting time. And it has little to do with planting in summer heat but everything to do with planting correctly and standing by one's work!!

Most plants can do quite nicely, thank you, on rainfall once they are established. So the real point to irrigation systems is getting the plants established in a climate where it is very common to plant in the spring or fall and *never* have to supplement water. Setting up a drip system to correctly water trees, shrubs and perennials is a fairly complicated business to get right. For all the times it is needed, a sprinkler is a much better investment.

That is a very regionally specific point of view :-)) In many parts of the country, many plants other than natives will NOT do nicely without supplemental irrigation, thank you very much!!. I live in an area with recurring summer droughts - it is typically dry as a bone here in summer - and few plants, even well established plants, will survive without routine summer irrigation. And even in those areas where recurring droughts or extended dry spells are not common, time to establish a newly planted landscape will generally require supplemental watering for at least two full growing seasons, perhaps longer.

And perhaps you have never installed an irrigation system. An inground pop-up sprinkler system is far more complicated and expensive to install than is a drip system and is far less efficient in delivering the needed water. Low emission irrigation systems are much preferred.

Honestly, can you really tell us that no one in the New England area ever waters their garden in summer?? I find that extremely difficult to believe.

Given that the 'region' is basically Bos-Wash, and the OP is in New Jersey, it counts :)

Aside from vegetable gardens and other gardens of annuals, watering of plants is far from common. So uncommon that the term 'sprinkler' refers to the thing that gets attached to a garden hose, not a pop up irrigation system.

If the plants are being watered faithfully -- by a person or some automated means -- then it is fine to plant. If there's not an automated system or a person cannot be trusted to water them faithfully, then it is not safe to plant.

OP doesn't sound very hands on.

Susan Wood, will you be willing to take a walk around every day and look at things to see if anything is struggling? Can you stick a finger into the soil to judge moisture? Will you pick up a hose and do supplemental watering if need be? Will you recognize plant stress when you see it?

If yes then plant.

But if you are a homeowner that wants to just write the checks, then wait. She could be urging you to do it now because it is her slow season. Minus any sort of guarantee she has nothing to lose by selling you plants and services that require your following up on their care.

I have used professional services like this only to install trees, so I may be ignorant of what is common, but every plant I bought and had installed came with a guarantee. I did have to have a tree replaced months later after it did not survive and they rolled up with another tree on another flatbed trailer and replaced it no questions asked.

The lack of any sort of guarantee is a big red flag for me, and double especially for August plantings.

I am also in NJ. Most of the landscapers around me will give a guarantee. I've used it before when a holly tree failed. Also, I'd wait till September although they are saying our August may be on the cool side.

"She could be urging you to do it now because it is her slow season."

This must be a regional thing as it is by no means the slow season here!! December and January, yes, but at no time during the growing season is it considered the slow or off season here!! I haven't had a summer vacation in over 25 years!!

I too consider the lack of any guarantee a cause for concern, which I mentioned previously. That always indicates to me a less than professional attitude about one's work and planting skills.

@gardengal I'm curious what your warranty is.

Since, I don't plant (design only), I don't warranty :-) But my primary contractor does, as does the nursery where most of our plant material is obtained. One full year, regardless of reason for demise/replacement.

to me that's insane. A lot can happen in a year, much of it having nothing to do with what we did. When I designed for a nursery I had clients straight up tell me that they never once watered the 12 screening plants we installed in March, and now that they're dead in September they want new ones.

We typically do 90 days, as that's plenty of time for a problem plant to manifest itself. If they sign on as maintenance clients, which most do, we warranty the plants for as long as we're caring for the property. Last year we did a $40k planting job, lost one solitary hydrangea. That's pretty typical for our success rate, so I feel like we're serving our customers well. We're all about the relationship.

but to the OP's question, I guess it depends on the area? We're one zone warmer down the coast and we generally don't plant from mid-June thru early September. The irrigation can stretch the season a tad bit, but hot is still hot.

Believe it or not, in the 10 years or so I have been working with my contractor, he has only replaced a few smaller plants under his guarantee. But then again, he is very good at what he does.....exceptionally so. To the point where I had no concerns about his moving a good sized, well established Japanese maple at the beginning of July (moved and re-established with dropping a leaf!!). And he almost always installs an irrigation system (usually a drip system), as many homeowners do not have the slightest idea how to water properly and they want the ease of an automated system. I have no idea how many replacement plants have been called for with other clients who employ their own contractor. And the DIY'ers are on their own, unless following up on any nursery guarantee.

As to the nursery guarantee, one year for trees and shrubs is standard in my area. When I worked at the nurseries, it was part of my job to process returned plants and initially I used to balk at giving a store credit or replacing a plant that was obviously not watered properly (many of them still in their original nursery container). But then I was told in no uncertain terms by the nursery owner that returns constituted a very minor percentage of total sales (less than 3%) and was an accepted cost of doing business, customer satisfaction being of bigger economic importance than a few returned plants. I will say that in my years of doing this sort of activity for various nurseries I have been associated with that returned trees were highly uncommon. It does happen but remarkably infrequently.

The nursery I designed for had a 12 month, one time replacement guarantee. What I learned pretty quickly was that the issues that killed plant #1 (improper watering, pest or disease pressures) were almost definitely going to wipe out plant #2 as well. As a result, I always drove home the point that if they see a plant doing ANYTHING that ooks them out after the original planting, call me and I'll pop by when I'm in the neighborhood.

I found that it was a tremendous customer relationship builder, and it usually headed off a need for replacement. The results of that were what led me to structure my warranty the way I did. After all, the customer just wants a successful planting and a great looking property with a minimum of hassle. Seeing my car at the curb for 10 minutes while I do a little pruning and change the irrigation clock to not be at 60 minutes per shrub zone is a lot less hassle than a crew coming out and replanting stuff.

"As to the nursery guarantee, one year for trees and shrubs is standard in my area."

Mine as well.