Planting calendar
August Planting Guide for Seattle, WA: Raised Beds, Containers & In-Ground
In August, Seattle gardeners can focus on planting cool-season crops and preparing for fall harvests in raised beds, containers, and in-ground gardens. This month is ideal for sowing leafy greens, root vegetables, and starting some fall flowers indoors. Be mindful of the approaching cooler weather and shorter days when planning your garden.
Plant now (quick list)
lettuce, spinach, radishes, kale, beets, carrots, broccoli, cauliflower
Plant now
- lettuce
- spinach
- radishes
- kale
- beets
- carrots
- broccoli
- cauliflower
- turnips
Start indoors
- cabbage
- brussels sprouts
- collard greens
- chard
- parsley
- dill
- cilantro
- pansies
- snapdragons
Avoid
- tomatoes
- peppers
- eggplants
- beans
- corn
- summer squash
- cucumbers
- melons
- basil
Next 2 weeks
- water raised beds and containers deeply to prepare for cooler nights
- apply mulch to retain soil moisture and regulate temperature
- thin seedlings of leafy greens to avoid overcrowding
- start hardening off indoor seedlings for transplanting
- monitor for pests like aphids and treat early
- prune spent summer crops to encourage new growth
- check soil pH and amend if necessary
- plan crop rotation for fall planting
- clean and store garden tools
FAQs
Can I plant tomatoes in August in Seattle?
August is generally too late to start tomatoes outdoors in Seattle due to the shorter growing season and cooler temperatures approaching.
How often should I water my raised beds in August?
Water deeply about 2-3 times per week, adjusting based on rainfall and soil moisture to keep roots hydrated without overwatering.
Is it necessary to start seeds indoors in August?
Yes, starting cool-season crops indoors in August gives them a head start for transplanting in early fall.
What are good companion plants for leafy greens in containers?
Herbs like parsley and dill, as well as flowers like pansies, can complement leafy greens and help deter pests.
When should I expect to harvest radishes planted in August?
Radishes typically mature in about 3-4 weeks, so you can expect harvests by early to mid-September.
Next steps
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