Soft washing uses a cleaning solution that is applied gently and rinsed off. Around plants, careful contractors wet the landscaping first, keep the solution close to the wall or roof, cover delicate plants when needed, and rinse again afterward. Pets stay inside until surfaces dry, and wash water is kept out of storm drains where possible. Ask any contractor, Rob included, exactly how they protect your plants.
The short version
- A soft-wash solution is a cleaner, often with a surfactant that helps it spread and cling, applied at low pressure and then rinsed.
- Plants are protected by wetting them first, controlling where the solution goes, covering delicate ones, and rinsing afterward. No method removes all risk.
- Wind, hot sun, tall roofs and plants hugging the wall make protection harder, and a good contractor adjusts or reschedules.
- Keep pets and children away until surfaces are dry and the area has been rinsed.
- Storm drains in most northern Illinois streets lead to creeks, ponds and lakes without treatment, so wash water should not be sent into them.
- Ask the contractor how they protect plants before you hire. A clear, specific answer is the best sign you can get.
What is actually in a soft-wash solution, in plain terms
Soft washing is a method, not a single product. The idea is to apply a cleaning solution at low pressure, let it work on the organic growth and film for a short time, and then rinse it away with plain water. The low pressure is what separates it from pressure washing, where the water itself does the cutting. The distinction is covered in Soft Washing vs Pressure Washing: Which Does Your Surface Need?.
Most solutions of this type combine two kinds of ingredient. One is the active cleaner that breaks down algae, mold and other biological growth. Many professionals use an oxidizing cleaner of the bleach family for that role, while some use milder or specialty products depending on the surface and the job. The other is a surfactant, which is a soap-like ingredient that lowers the surface tension of water so the solution spreads evenly and clings to a vertical wall long enough to work.
This guide describes the general practice. Strengths, mixes and products vary by contractor and by surface, and none of that is covered here. What matters to you as the homeowner is not the chemistry but how the contractor controls where the solution goes, how much is used, and how it is rinsed.
Why plants are the part people worry about, and why the worry is reasonable
Foundation beds sit right where siding is washed, and gardens, shrubs and vines often grow against the wall. Cleaning solutions and runoff can burn leaves, especially tender growth such as new spring shoots, annual flowers and vegetable plants. Damage tends to show up as browning or spotting on leaf edges within a day or two. Well-established shrubs and trees are generally more tolerant than delicate perennials, but that is a tendency, not a rule.
It is also reasonable for a homeowner to be wary of any claim of zero effect. A contractor who says plants are never a concern is either not thinking about it or not telling you the full story. A better answer is a description of the steps taken to reduce the risk, plus honesty that some risk is always there, particularly in wind or with plants pressed against the wall.
Lawn grass is usually the least sensitive, though a concentrated spill on turf can leave a brown patch. The most vulnerable are plants growing in contact with the surface being washed, and small or potted plants that cannot be moved away easily.
How a careful crew protects landscaping: wet, shield, control, rinse
Several routine practices cut the risk. The first is pre-wetting: plants and soil near the wall are soaked with plain water before any solution is applied, since a wet leaf takes up less of what lands on it, and the soil holds extra water that dilutes any runoff. The second is control. The solution is applied low and close to the surface, with attention to wind direction, so it does not drift or spray onto the garden.
Third, delicate or small plants can be covered, tied back or moved, and tall shrubs against the wall can be pulled gently away. Fourth, after the surface is rinsed, the plants and the soil beneath are rinsed again with plenty of plain water to dilute and carry off any residue. Some contractors also keep a hose running on the bed during the job.
None of this is exotic. It is attention and time, and it is the reason a good crew does not rush. You can speed things up by trimming back plants that touch the walls and moving pots before the visit, which is part of the preparation described in How Do You Prepare Your Home for an Exterior Cleaning Visit?.
- Wet the plants and soil before the solution goes on.
- Apply low and close to the surface, and watch wind direction.
- Cover or move delicate and potted plants, and pull back shrubs where possible.
- Rinse the surface, then rinse the plants and soil again.
- Stop or reschedule if conditions make control difficult.
Weather, tall walls and roofs: when protection gets harder
Conditions make a large difference. Wind carries mist onto plants, neighbors' yards and cars. Strong sun and heat dry a solution on the surface too quickly and can leave streaks, which leads to more rinsing and more runoff. Cool, overcast, calm days are easier to control than hot, breezy ones.
Height raises the stakes. Rinsing a second story or a roof sends a lot of water down onto whatever is below, including plants, decks and patios. Roof runoff in particular flows through gutters and downspouts, and it ends up wherever the downspouts discharge. A contractor should know where that is and plan for it, for instance by wetting and protecting the discharge point. Roof washing is discussed further in Is Roof Washing Safe for Asphalt Shingles?.
A contractor who is willing to stop for the wind, shift the work to a different day, or leave a section for later is showing the judgment you want. It may cost a bit of scheduling flexibility, and that is worth it.
Pets, children and the hours after cleaning
Keep dogs, cats and children inside during the work and away from treated surfaces and the beds beside them until the surfaces are rinsed and have dried. Pets tend to lick their paws after walking through wet grass and sniff at damp mulch, so they are the ones most likely to come into contact with residue. If a pet has been in contact with a cleaning solution or shows signs of distress such as drooling, vomiting, or irritated skin, contact a veterinarian. For a child, contact a poison control center or a doctor.
Also move pet bowls, toys, and children's play items off the area beforehand, and bring them back only after the surface has been rinsed and dried. If you keep chickens, bees, a pond, or a vegetable garden, tell the contractor ahead of time, since those call for extra planning or a no-spray buffer.
Fish ponds and water features deserve a special mention. Cover or divert them, and make sure no runoff can reach them. Ask the contractor how they handle that, and do not assume it will be taken care of.
Storm drains, creeks and lakes: where the wash water goes
In most northern Illinois towns the storm drain at the end of the driveway is not connected to a treatment plant. It carries street runoff directly to a creek, retention pond, wetland or river, and from there to places like the Fox River and its lakes. That is why cleaning solutions, soaps, and the dirt and algae that come off a house should not be sent down a storm drain.
Roofs and siding are generally rinsed over landscaping, where soil and plants can take up and break down diluted residue, rather than onto pavement that slopes to the street. On a driveway or patio, where wash water has to flow somewhere, a careful contractor will try to keep it on the lawn side, block the drain, or collect it, and will avoid pushing it down the street. Municipal rules on this vary, so the village can tell you what applies.
If you live on a lake, creek or pond, mention it. Lakefront and creek-side lots call for closer attention to runoff, since the shoreline is only a few steps from the wall. The same is true of homes with a sump pump that discharges to the street.
Questions to ask any contractor before the job
You do not need to know the chemistry to judge a contractor. You need to hear specifics. Ask how they protect the plants along each wall, what they do before, during and after the application, and what happens if a plant is damaged. Ask what they do about wind, how they handle runoff from a roof, where the wash water from the driveway goes, and what they ask you to do in advance.
A confident answer sounds like a description of steps, such as wetting, covering, rinsing, and rescheduling. A vague answer, like we have never had a problem, or one that treats the question as an annoyance, is information too. The broader checklist for hiring is in How Do You Choose a Good Exterior Cleaning Contractor?.
Rob is glad to answer these questions, and the sensible time to ask is when you text (815) 451-0106 for a quote. Tell him what is growing along the walls, whether you have pets or a pond, and where the downspouts run, and he will tell you how he plans the job around them.
What this guide cannot tell you
No guide can promise how every plant will respond. Species, health, weather and timing all matter, and a stressed or tender plant may show marks even when everything is done well. If you have a rare or valuable plant, a prized garden or an edible bed, move it or cover it yourself, or ask the contractor to leave a buffer.
Product labels and safety data sheets are the authority on the specific materials a contractor uses. You can ask to see them. If you have concerns about health, allergies or sensitive neighbors, talk to your doctor or the product manufacturer as well.
For mold and algae on siding specifically, including why cleaning the surface is only half of the answer, read Mold and Algae on Siding: What It Is, Whether It Matters, and How to Clean It. For when to skip a wash and wait, When Is the Best Time of Year to Clean Your Home's Exterior in Northern Illinois? is the place to look. soft washing is the service itself, and the quote is free.