Most plant damage from a house wash is preventable with an hour of prep and a plan for the rinse water. Here is what actually harms plants and lawn, how to prepare each type of planting, a countdown from two weeks out and how to choose where the runoff goes.
In This Article
What actually harms plants and lawn
A house-wash mix is diluted before use, and it is rinsed off the wall with plenty of water. The trouble starts when some of it lands on a leaf and dries there, or when runoff pools around roots.
- Dried residue on leaves. Mist that sits in the sun and is never rinsed can scorch foliage.
- Pooling runoff. Water collecting in a low bed keeps the product in contact with roots for longer.
- Covers left on. A tarp over a shrub traps heat in sunshine and cooks what is underneath.
Wet foliage handles overspray far better than dry, and lawn tolerates a diluted rinse well. The narrow strip of grass and soil along the foundation takes the most, so that is where prep pays off.
Prep by plant type
- Shrubs and perennials against the wall take direct overspray and runoff. Cut them back so there is a hand's width of clearance, then soak them before the wash.
- New plantings and fresh sod have shallow roots and little reserve. Tell the crew, keep them well watered and ask that they be rinsed longest.
- Thin-leaved shade plants scorch more easily than thick, waxy ones. Soak them, and cover them briefly if the crew agrees.
- Potted plants and hanging baskets have a small soil volume and no drainage buffer. Move them to a shaded spot well away from the wall.
- Vegetable and herb beds should not take any runoff. Keep them out of the drainage path, cover them and move containers.
- Climbing vines grow into the siding, so treatment reaches them. Ask whether they should be detached, and agree who does it.
- Rain barrels, ponds and wells risk contamination. Disconnect the downspout feeding a barrel and keep runoff away.
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A countdown from two weeks out
- Two weeks out. Walk the walls with a notepad. Note every plant within two metres, trim back anything touching the siding and find the outdoor tap.
- One week out. Tell the neighbours and mention any fence-line plants. Ask the crew how plants will be protected and rinsed.
- The day before. Mow, and rake cuttings and leaves away from the base of the walls. Water beds normally so plants are hydrated but not soggy, and set the sprinkler timer to off for the wash day.
- Morning of. Move pots, furniture, bird feeders and toys. Disconnect rain barrels, close windows, bring pets indoors and move cars off the drive.
- During the wash. Stay clear of the mist, keep windows shut and check that rinsing covers the plants as well as the walls.
- Same evening. Water the beds deeply and remove any covers, then look at the plants again the next morning.
Plan where the rinse water will go
Walk the yard and follow the slope. Rinse water will flow the same way rain does.
- Good destinations: a wide lawn or a large planting bed, where soil absorbs and dilutes what arrives.
- Poor destinations: the driveway and street. In most Ontario neighbourhoods a catch basin empties to a local creek or river, not to a treatment plant.
- Keep clear: vegetable beds, ponds, rain barrels and any private well.
- Watch the neighbour's side. Do not send the flow toward their garden or patio.
Soil matters as well. Frozen or waterlogged ground cannot absorb much, so rinse water runs across the surface instead of soaking in. In spring, wait for the ground to thaw, and avoid washing straight after a downpour.
Municipalities set their own rules on what may enter storm drains, so check your municipality's current guidance. For the wider environmental picture, read about eco-friendly exterior cleaning and sustainable exterior cleaning practices.
After the wash: water, watch and report
Plant scorch, if it happens, usually shows within a day or two as brown or bleached leaf edges and sudden wilting. Water deeply with fresh water, skip fertilizer and take dated photos. Report anything promptly to whoever did the wash, since a fast report is easier to sort out.
Prep works best when the crew knows about it. When you request a quote for soft washing, mention new plantings, vines and vegetable beds, and ask how each will be handled. D&D confirms quotes in writing before work begins, so details like these can go straight into the scope.
Key Takeaways
- Plants suffer from dried residue, pooling runoff and covers left in the sun, and wet foliage copes far better than dry.
- Prep by plant type: clear shrubs from the wall, move pots, keep edibles out of the runoff path and tell the crew about new plantings and vines.
- Follow the slope of the yard so rinse water goes to lawn or wide beds, and away from the street, ponds, rain barrels and wells.
- Water deeply after the wash, check plants for a day or two and report scorch promptly with dated photos.
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