Rose City Roots

Gardening in Portland since 1996.

Portland irrigation winterizing in October with drip lines and hose bib being drained before frost

Irrigation Winterizing Week

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The forecast is dry and warm through Thursday, which is exactly the window to drain the system while it is still comfortable to work outside.

This Week's Action List

  1. 1

    Shut off the hose bib supply inside the house, open the outdoor spigot, and disconnect every hose before Friday. A single hose left attached is the most common reason burst pipes show up in Portland basements in November.

    Shut off the hose bib supply inside the house, open the outdoor spigot, and disconnect every hose before Friday. A single hose left attached is the most common reason burst pipes show up in Portland basements in November.
  2. 2

    Drip systems need the water pushed out, not just turned off. Open the end caps on each zone, run the system for two minutes to flush, then leave the caps loose so any residual water can escape when temperatures drop.

  3. 3

    Insulate above ground backflow preventers and pressure regulators with foam covers or a wrap of old towels inside a plastic bag. These brass fittings are the single most expensive thing to replace after a freeze.

    Insulate above ground backflow preventers and pressure regulators with foam covers or a wrap of old towels inside a plastic bag. These brass fittings are the single most expensive thing to replace after a freeze.
  4. 4

    Clay and terracotta pots crack from the inside out when wet soil freezes. Move empties into the garage this week and consolidate planted ones against the south wall of the house where radiant heat buys a few degrees.

  5. 5

    Thursday hits 80°F, which is a gift for fall shrub planting. October through November is the single best planting window in Zone 8b because roots keep growing in warm soil long after top growth stops. Water each new shrub in with 3 to 5 gallons and skip the fertilizer.

  6. 6

    Get fava beans in the ground this week while soil is still above 55°F. Sow seeds 1 inch deep and 4 to 6 inches apart in any bed you want covered through winter. Varieties like Aquadulce and Windsor overwinter reliably in Portland.

  7. 7

    Tulips go in last, after the soil cools below 60°F, so hold them for late October or early November. Daffodils, alliums, muscari, and crocus can go in now at a depth of three times the bulb height.

  8. 8

    Rake every rose leaf off the ground and out of the beds, then bag them for the green bin rather than the compost. Overwintering black spot spores live on fallen leaves, and this one task does more for next year's roses than any spray.

  9. 9

    Hold the pruners on roses, rhododendrons, camellias, and all evergreens until late February. Dormant pruning on apple, pear, plum, and bare deciduous shrubs opens around October 20 to 25 once leaves have fully dropped.

    Hold the pruners on roses, rhododendrons, camellias, and all evergreens until late February. Dormant pruning on apple, pear, plum, and bare deciduous shrubs opens around October 20 to 25 once leaves have fully dropped.

Frequently Asked Questions

When should I winterize my irrigation system in Portland?

Drain and blow out drip lines by mid October, even though the average first hard freeze is around November 15. Portland can drop to 28°F any night after October 15, and the damage from one surprise freeze costs far more than winterizing a few weeks early. A dry week in the 70s like this one is the ideal working window.

Is it too late to plant shrubs in Portland in October?

October is the peak planting window for shrubs and trees in Zone 8b, not the end of it. Soil is still warm enough for root growth through November, and winter rains do most of the watering for you. Skip fertilizer so plants move into dormancy on schedule.

Can I plant tulip bulbs in Portland in early October?

Tulips should be the last bulb planted, usually late October or early November once soil cools below 60°F. Planted too early in warm soil, they can sprout prematurely or rot. Daffodils, alliums, crocus, and muscari can go in now.

Should I prune my roses in October in Portland?

No. Rose pruning waits until February in Zone 8b, after the worst freeze risk passes. Fall cuts stimulate tender new growth that gets killed by the first hard freeze. Focus October energy on raking up fallen rose leaves to break the black spot cycle.