As short as the growing season is in Zone 4, you might be surprised how late you can plant to get a fall crop. Zone 4 stretches across the northernmost United States, including the northern part of the East Coast of the United States, including New York, Vermont, New Hampshire and Maine. In the Midwest, most of Michigan and Wisconsin are in the zone as well as southern Minnesota and northern Iowa. In the West, zone 4 takes in the Rocky Mountain states. The first frost date in Zone 4 is sometime during the month of September depending on both latitude and altitude.
Plant another round of leafy greens like Swiss chard, kale and Asian greens. Even though carrots take a long time to mature, if you get them in by the first of August you can still harvest late in the autumn. All can take “chilling,” which is a drop in soil temperature to about 50 degrees Fahrenheit.
When you plant in early to mid-July be cautious of the heat and sun. You will be planting cool-weather plants, so don’t broil them when they are young. Screen them from the sun with floating row cover or screening. Start tender greens like lettuce in a semi-shady spot (such as behind your pole beans!). Keep the soil moist all the time until germination. Sow seeds twice as deep as you would in the springtime.
- Add one last planting of gladioli bulbs for flowers into fall.
- Mulch around perennial plantings, other than the ones you want to spread. Use straw, leaves, or other organic, weed-free material to control weeds and conserve moisture.
- Many perennials come into bloom this month, as does the day lily. One nice thing about day lilies is that they can be planted almost any time the soil can be worked. However, early spring and late summer are the best times for transplanting. Set the crown (where the stem and root join) about one-half to one inch below the soil surface. Plant day lilies 18 to 24 inches apart so they have room to spread.
- Petunias, coleus and other summer annuals might be leggy by now. Pinch them back by as much as half their length just above a leaf to encourage bushy growth and more flowers. Fertilize with a balanced liquid fertilizer.
- Leave faded flowers on those plants that form ornamental seed heads, pods, or berries. Keep up with dead-heading for the rest to keep plants compact and encourage more blooms.
- Annuals need about an inch of water a week, either from rain or irrigation. Try watering once a week, soaking the soil well. Deep watering = deep roots.
- Harvest sweet corn when silks are brown and punctured kernels produce a milky juice.
- Prevent blossom-end rot on tomatoes by providing plants with at least an inch of water each week and enough calcium, either from garden lime or another source. Mulch heavily around tomato plants to conserve moisture and keep soil from splashing up on the leaves. Many tomato diseases are soil-borne.
- Let melons ripen on the vine–this is where they will develop their best flavor.
- Empty areas of the garden where the crops have finished can be replanted with either a fall vegetable crop or a cover crop of clover, peas or vetch to help control weeds. Cover crops can be tilled into the soil later to add humus and nitrogen to the soil.
- To enjoy fresh vegetables throughout the fall, plant fall crops in July and early August, including root crops (e.g., beets, turnips); leafy greens (e.g., spinach, lettuce); and kohl crops (e.g., Brussels sprouts, broccoli, cabbage).
- When to plant depends on the crop. Put your cabbage family transplants in the garden by mid-July. Seed beets, turnips, and Swiss chard by the end of July, but wait until August to plant lettuce, spinach, and radishes.
- If using pesticides to control July pests such as the Japanese beetle or Mexican bean beetle, always follow label directions. Use only as much as you need and avoid applying in mid-day heat, on windy days, or when plants are in flower and bees are present.
- When watering plants, be sure to water well. Actively growing vegetable plants need at least an inch of water per week, either from natural rainfall or watering. To prevent foliar diseases, apply water directly to the soil and avoid wetting the leaves of plants if possible.
- For peak flavor, basil, sage, marjoram, oregano, mint and tarragon are best harvested just before bloom. Start more basil from seed for combining with those September tomatoes, and dill for late pickles. Harvest lavender, rosemary and chamomile as they flower, blossoms and all.
- Summer blooming shrubs should be pruned for shape after they have finished flowering. Remove any dead or diseased branches. Don’t prune most hydrangeas unless you have to for size. Most varieties bloom on old wood. Research the cultivar you planted to see if it is one of the ones that can be pruned and still flower.
- Fertilize flowering shrubs like Rhododendrons and Azaleas as well as Camellias immediately after they have finished flowering with a ‘Rhododendron’ or ‘Evergreen’ type fertilizer.
- Dead head the developing seed pods from your Rhododendrons and Azaleas to improve next year’s bloom. Be careful not to damage next year’s buds, which may be hidden just below the pod.
- Trees are especially vulnerable to drought, particularly the oldest and the youngest (those planted in the last couple of years). Water deeply, as with a drip hose. Or Tree-Gator. Always be on the lookout for dead, damaged, diseased wood in trees and shrubs and prune them as needed. Ditto with suckers and water sprouts.
- Keep the lawn mowed even though this is usually a time when grass growth slows. If the weather is dry, mow high, but less often. The key is to only cut one third of the grass off at any mowing. Cutting too short, or cutting too much of the grass off at one time, can reduce the ability of grass to withstand drought stress.
- Contrary to popular belief, a brown lawn isn’t necessarily a dead lawn. Grasses go dormant in times of drought, but will quickly return to life with the fall rains. If a lush green lawn is important to you, and you don’t mind mowing, water it regularly and deeply. If a water shortage is expected, or you hate tending to grass, you may choose to just let your lawn go dormant and water it as seldom as once a month.