Getting the garden ready for fall
Late August in the garden means we’re burning daylight — keep harvesting while taking advantage of cooler temperatures for fall planting.
Vegetables
Say it ain’t so that Oct. 7 is the average first fall frost date in our area. That gives direct-seeded fall crops a good six weeks to get growing.
Pull out your cool-season stash of seeds. Look for shorter maturing leafy greens of lettuce, spinach, arugula, Asian greens, Swiss chard, bok choy, and kale. Greens can easily be harvested when only 4 inches tall at the baby greens stage, which is usually about 30 days of growth.
If you’re low on seeds, garden centers are full of the tasty salad blends like mild mesclun blend (mesclun means a mixture of types, flavors and colors), gourmet baby greens, winter greens blend and more. Many mature in 30 to 40 days.
Also, direct seed quick-maturing radishes and onion sets. Garlic seed can be planted later in September to October.
If short on space in the garden from large tomato plants or pumpkin vines, use well-draining containers with fresh potting soil. These can easily be moved indoors on cold nights.
Micro-greens — the first set of leaves from seedings — are a popular restaurant trend, tasty and full of antioxidants. They easily grow in shallow seedstarting trays that aren’t in use right now. Set them on a sunny table or on the ground where they can easily be watered and harvested. Micro-greens are ready in 10 to 20 days. When ready, simply cut the small leaves right above the soil line and use for salads, soups or sandwiches.
Once harvested, turn the soil over in the container and seed again. They can easily be brought indoors on cold nights and placed near a sunny window or under grow lights.
As with any direct seeding, first remove any spent foliage and weeds. Loosen the soil to 8 inches to allow good root growth. Seed a bit deeper than spring planting and keep the seeds watered for quick germination.
Later when temperatures get colder, use easy (often low cost or repurposed) materials to make cold frames or tunnels so plants can be harvested into late fall and winter. Here’s a video on building tunnels.
Trees, Shrubs, Bulbs and Perennials
There are several advantages to fall planting. It’s less frantic than spring when there’s a rush to plant for the summer season. Warm soil helps new plants get established before the ground freezes. There are fewer pest and disease issues and no need to fertilize, which may promote too much new growth that can get hurt by frost.
Bonus: Many plants are on sale in the fall.
Viewing trees growing in the nursery or garden center during the fall gives you great information. Often you can see the leaf fall color or if it produces seeds, which may or may not be a desirable trait.
The selection may not be as plentiful as spring but fall tree and shrub planting will give you a head start on next spring.
Hold off planting evergreen or conifer trees and shrubs until the spring when they have a longer window to get established.
Be sure to call 8-1-1 location services before digging trees.
Plant correctly, not too deeply. Check out this helpful resource for recommended trees, plus approved trees in Denver right of ways and planting tips.
Fall bulb planting is almost mandatory for any gardener. They herald the spring in late winter with staggered blooming (per bulb type) through early summer. Shop now for the best selection.
Don’t forget perennials for late winter or early spring bloom to plant now: hellebores, pasque flower, primroses, bleeding heart, columbine and anemones.
Moving and dividing perennials in the fall will save time from doing this chore in the spring. Large hostas appreciated being divided and replanted in the fall. Share extras with your friends and neighbors. Peonies can be planted (new plants) or divided. Be sure not to plant them more than 2 inches above the buds on the roots. If planted too deeply, they will not bloom.
We love fall mums, but the big blooming plants being sold now may not get established if fall planted, so enjoy them, but the best time for mum planting is spring.
Seasonal fall blooming plants may not be discounted; pick up some anyway and place around the patio, garden or entry way to welcome the fall season.