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Seattle summer seeds

Planting a Fall Vegetable Garden

We are so lucky in the Pacific Northwest to be able to grow veggies nearly year-round with a little help from season-extending materials but the fact is that many vegetable gardeners don’t take advantage of the opportunities that exist in mid-to-late summer to plant vegetables for fall and even extra-early-spring harvests.

Maybe we’re all a little less confident of what to plant and when. Or maybe, arms laden with enormous squash and eyes glued to ripening tomatoes, we stay in the “care-and-harvest” zone, forgetting that too soon we will be lamenting the lack of garden-grown produce (and sunshine).

Maybe we hear the term “fall vegetable garden” and think fall planting. But mid-July through August is the ideal time to plant. Whether you already have a thriving edible garden or haven’t had time to start a vegetable patch this year, it’s time to get outside and get started! This fall gardening guide will help you plan and plant a successful fall garden.

Planning the Fall Vegetable Garden

Missed planting peas last spring? No problem. In the PNW, we can grow peas for a fall harvest! Have some space where your newly-harvested lettuce used to grow? It’s perfect for fall beets, broccoli, or even more lettuce.

Let’s look at where to plant, how to improve the soil, and whether you should plant seeds or starts (baby plants), then I’ll provide a list of vegetables suitable for the fall/winter garden.

Where to Plant

When planting for autumn, it’s a good idea to practice crop rotation. If you can, plant something different than what you had in that spot in spring and summer. This is especially important for crops in the Cabbage family (broccoli, kale, radishes), and for carrots and onions. Some of the pests that attack these vegetables could still be around and planting the same thing in the same spot makes it all that much easier for them to feast.

Remember also that you can sow seeds or even plant starts (baby plants) in tight spaces if the vegetables that are currently growing there will be harvested soon. Radishes and carrots can be planted in between rows of maturing lettuce or bush beans, for example.

Improving the Soil

Your summer vegetables have most likely used up essential nutrients in the soil, so adding a natural vegetable fertilizer (try Dr. Earth or Espoma brand) will give your new plants a much-needed boost. You can also amend your soil with high-quality compost, such as E.B. Stone Planting Compost or Gardner & Bloome Harvest Supreme. For containers, always use potting soil (again, E.B. Stone and Gardner & Bloome offer excellent options) mixed with fertilizer, added according to package directions.

Now is also the time to mulch your soil, after planting, with several inches of compost (Gardner & Bloome Soil Building Conditioner is great as mulch) to keep summer’s heat in the soil and help retain soil moisture.

If you decide not to plant your entire space, consider sowing a cover crop such as crimson clover, vetch, winter peas, or favas in the fall. These legumes are nitrogen fixers and will improve your soil. Let them grow through the winter, then till them into the soil in early (can’t emphasize that enough) spring and voilà – improved soil!

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Starts or Seeds?

Planting starts will allow you to harvest earlier in many cases. For many of the edibles mentioned below, starts are preferable to plant in August. However, fast growers like lettuce, parsley, radishes, arugula, or vegetables you will harvest small (baby carrots and young leaves of spinach, kale, and Swiss chard) can easily be grown from seed or starts, depending on your preference. If sowings of seed fail to germinate in early August because of heat and inconsistent water, try again in late August and September when they may germinate more easily.

Note: Many vegetables have varieties that are best suited for fall and winter. At Swansons, we carry fall gardening varieties of plant starts in July and August. For seeds, check seed packet information to see if a variety is recommended for fall gardening.

What to Plant

Vegetables are often separated into two groups: cool-season and warm-season. The warm-season veggies are at their peak at the height of summer: think tomatoes, squash, cucumbers, and peppers. Cool-season veggies prefer milder weather and can generally be planted in spring and again in late summer/early autumn.

Some cool-season veggies grow fairly quickly and, if you plant them now, you will be able to harvest this year. Lettuce, most greens, radishes, and peas can be harvested before the first frost or covered for protection (see “Cold Protection”, below) while beets and carrots can handle a little frost and may even become sweeter for it.

Other cool-season vegetables can be planted now but won’t be ready until next year. They will “overwinter,” meaning they will stay mostly dormant until early spring and then begin growing again, giving you earlier harvests than if you waited to plant them until early spring.

So what should you plant? Here are some options.

Plant these in mid-July for Fall Harvests

These vegetables need to be planted very soon so they will have time to mature by fall.

Garden Cover Crops

Seeds are sown into vegetable garden soil—typically in the fall—to preserve and enhance the soil over the winter. They provide a host of benefits:

Prevent soil erosion and compete with weeds in winter when the soil is not being cultivated.

Improve soil porosity and tilth (the physical condition of the soil)

Add large amounts of organic matter to the soil when the lush growth of green, immature crop is tilled under in early spring. Nutrients (nitrogen, phosphorous, potassium, calcium, etc.) are returned to the soil. Cover crops planted primarily for nutrients are known as “green manures.”

Legumes are host to nitrogen-fixation bacteria which extract nitrogen from the air and store it. When turned under, the nitrogen is returned to the soil.


After produce is harvested, till the plant residue into the soil where it will decompose to produce more humus. This prepares the soil for the seed. Use a drop spreader, a broadcast spreader or broadcast seed by hand. For better coverage, make two seeding passes over the garden at right angles to each other. Lightly rake the seed into the top 1/4 inch of soil. The seed must be covered and be in firm contact with the soil for best germination.

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Nitrogen fixers. Legumes benefit from use of a seed inoculant when planting.

Austrian Peas
Large-seeded legume, very good for building tilth and adding organic matter to the soil. Perfect if you’re getting a late start planting your cover crop and/or planning to wait until late spring to plant your garden. Peas like well drained and fertile loam soils.
Planting time: late Sept. to mid Nov. Recommended Seeding Rate: 1 lb. per 200 sq. ft.

Crimson Clover (An Annual Clover)
Colorful and versatile, crimson clover grows readily on both sandy and clay type soils (best with good drainage) and can be used as either a summer or winter cover crop. The dense mass of hairy stems and leaves is very effective against weeds, and will return a large amount of organic matter and nutrients to the soil.
Planting time: late Sept. to mid Oct. Recommended Seeding Rate: 1 lb. per 1000 sq. ft.

Faba Beans (aka Fava Beans)
Earliest of the green manures to mature, allowing you to till them under in mid to late April and get a head start for spring. Its deep taproots help break up clay or compacted soil as well as add nitrogen and humus. Some may experience an allergic reaction to pollen from faba bean blooms.
Planting time: late Sept. to mid Nov. Recommended Seeding Rate: 1 lb. per 100 sq. ft.

Common Vetch
Less winter-hardy than hairy vetch, common vetch is best adapted to well-drained, fertile soils. It is not tolerant of wet soils. It is often seeded with a small grain, such as rye. Vetches are annual, vine-type legumes with leaves ending in tendrils.
Recommended Seeding Rate: 1 pound per 400 square feet


Add minimal nitrogen, but are the best tilth builders and quick erosion control.

Rye Grain
The perfect tilth builder. And perhaps the most popular cover crop for erosion control because it germinates quickly and grows rapidly in cool weather. Also very hardy.
Planting time: August to early Nov. Recommended Seeding Rate: 1 lb. per 250 sq. ft.

Another great tilth builder and the best summer cover crop.
Planting time: March to July. Recommended Seeding Rate: 1 lb. per 1000 sq. ft.


Gardenway Cover Crop Blend
The most complete Northwest cover crop blend! This mix combines the great growing characteristics of all the major green manure crops suitable for our climate and soils west of the Cascades. Ingredients: 30% Cereal Rye, 27% Austrian Peas, 29% Triticale, 5% Common Vetch, 5% Annual Rye Grass, 2% Crimson Clover.
Planting time: mid Sept. to late Oct. Recommended seeding rate: 1 lb. per 500 sq. ft.

Summer Gardening in the Northwest

The only way to ensure you have the freshest vegetables is to grow them yourself. Plus, with growing your own you know they are commercial herbicide and pesticide free.

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By mid-summer, most gardens are in full swing. Crops such as lettuce, radishes, peas and spinach have had their growing season and are being harvested by this point. Others can be planted now for a delightful Fall Harvest.

Lettuce/Mesclun Mix – the earliest time to plant lettuce is as soon as the risk of frost has passed (generally the second or third week of May). It is a fast-growing vegetable and is ready for the picking in late June/early July. Most lettuce will quickly bolt to seed if the temperatures rise too high, but some varieties are exceptionally well adapted to heat. The best part is, you can enjoy lettuce again in the fall, as the next planting can be the third week of July for an end of September harvest.

Australian Yellow Lettuce should be called King of Summer, because we can not get it to bolt, even through the hottest days. Its bright green/yellow leaves perk up every night and continue to produce while we harvest the lower leaves.

There are other things to keep in mind during the summer when it comes to gardening. They are:

Keeping the weeds down during the summer can seem like a never-ending battle. It is important to remove them before they go to seed (meaning, the flowers die off and seeds are revealed.) Toss only young weeds in the compost pile. If they have set seed, they need to be thrown in the trash, or better yet, burned. The heat of the compost does not kill all weed seeds.

Water thoroughly, but less often, as only giving your garden a sprinkling does more harm than good. Water during the evening, as the moisture will quickly evaporate in the heat of the day. If you have vegetables that are visibly stressed, spot water during the day then give the entire garden a thorough soaking once the sun has gone down. Rainwater is the first choice for your garden (see: Seattle Rain Barrels), but city/well water will suffice if rainwater is in short supply.

Check your crops for pests and diseases. The sooner you spot a problem, the easier it will be to take care of it. Spider mites and aphids can quickly cause irreparable damage to plants, so getting rid of them quickly is crucial. Many pests and diseases will take advantage of the gardener’s neglect; they seem to know just when you’re on vacation.

Gardening is a rewarding activity, with the harvest being the most rewarding of all. By taking the steps above, you will soon be enjoying a healthy, bountiful harvest. Happy gardening!

A Year-Round Garden Planner will help you plant and harvest at the correct times of the year (ALL year) for your specific climate.