Zone 4 – Vegetable Planting Calendar Guide

Zone 4 has a shorter growing season compared to most other USDA plant hardiness zones in the United States. This zone typically experiences a last spring frost around June 1st and a first fall frost around October 1st, though these dates may vary by a week or two depending on weather conditions, so it's important to pay close attention to forecasts before planting. The minimum average annual temperature for Zone 4 is -30°F. When choosing vegetable varieties to plant in Zone 4, select those with faster maturing dates that can thrive within the shorter growing season. Watching the weather and choosing quick-maturing varieties will help ensure a successful vegetable garden in the limited Zone 4

Zone 4 Hardiness Dates

Last Frost Date- June 1st

First Frost Date- October 1st

Zone 4 Planting Schedule

Using the zone 4 planting schedule below will help you get the most out of your garden. Starting seeds indoors before your last frost date will give you a jump start on the growing season. Knowing when to transplant seedlings outdoors based on the zone 4 planting schedule will help to maximize your harvest.

January

Be vigilant in removing accumulated ice and snow from the branches of trees and shrubs to avert the risk of them snapping under the weight. Wrapping the trunks of young trees and those with delicate bark, such as linden, ash, mountain ash, and maple, can offer protection against the harsh winter elements. During these colder months, it's also an opportune time to tend to your indoor plants by wiping away any dust that has settled on their leaves, which can block sunlight and interfere with their natural processes of respiration and transpiration.

As you await the arrival of spring, begin strategizing for your upcoming garden. Consider the layout and plant rotation from the previous year to ensure soil health and productivity. If you're handy, you might also start building structures that will support your garden's growth, such as cold frames, trellises, or indoor lighting systems that can extend the growing season.

Lastly, make it a New Year's resolution to maintain a detailed garden journal. Documenting the performance of various flower and vegetable varieties in your garden will provide valuable insights for future planting and cultivation, helping you to identify which species thrive and which ones may need to be replaced or repositioned. Protecting trees and shrubs in winter offers more detailed guidance on these winter care practices.

February

Initiate the stratification process for any perennial seeds that benefit from this cold treatment to enhance germination. Ensure your gardening tools are thoroughly cleaned and sharpened for optimal use. If you haven't placed your seed orders yet, do so promptly to secure the varieties you desire for the upcoming planting season.

Gather all necessary supplies for seed starting to prepare for planting. Essential items include grow lights, heating mats, a sterile growing medium, and the pots or containers you prefer to use.

Now is the ideal time to begin sowing certain seeds indoors. Start with onions, as they require a longer growing period before transplanting. Additionally, consider starting flowers and herbs such as rosemary, impatiens, and begonias indoors, as they also need more time to germinate.

For those without woodworking skills, constructing a cold frame from straw bales is a simple and effective project to undertake at this time. This method can create a protected environment for your plants, allowing you to extend the growing season. For more guidance on starting seeds and preparing a cold frame, you can refer to resources like Zone 4 - Monthly Garden Calendar: Chores and Planting Guide and Zone 7 - Monthly Garden Calendar: Chores and Planting Guide. These guides offer tailored advice for gardeners in specific hardiness zones, but the general principles can be applied broadly.

March

If you haven't yet taken the opportunity, the current period is ideal for trimming your fruit-bearing trees, shrubs that produce berries, and other woody plants you may have around your home.

For those flowers that germinate more effectively after experiencing cold weather, such as Nigella, Poppy, and Larkspur, this is the opportune moment to plant them directly outside. The exposure to the remaining winter chill will help improve their chances of successful sprouting.

As we experience longer daylight hours and shorter nights, your indoor plants will begin to enter a new growth phase. If they require larger homes, this is the perfect time to repot them. It's also advisable to provide them with a nourishing feed to support their growth.

Now is also the moment to begin indoor seed starting for vegetables like broccoli, cabbage, cauliflower, celery, eggplant, head lettuce, and parsley. Additionally, it's wise to initiate the indoor sowing of most perennial flowers before this month concludes.

To sidestep the usual springtime flurry, consider servicing your lawn mower and any other power equipment now.

On days when the weather is cooperative, give your compost heap a turn. However, it's important to hold off on tilling your garden soil just yet. Tilling when the soil is still too cold and damp can lead to undesirable compaction.

APRIL

Prune the spent stems of flowers and grasses. Consider chopping these desiccated stems and plant remnants, then disperse them across the soil as organic mulch. This layer of decomposing leaves and mulch continues to serve as insulation, safeguarding the soil and your perennial plants against unexpected frosts in late spring.

It's now appropriate to rearrange perennial plants, provided the soil isn't overly moist. To test, see if the soil crumbles easily when prodded; if it forms heavy clumps, it's best to wait for drier conditions. This soil readiness test is also applicable when preparing vegetable gardens and flower beds for annuals. Hastily working with wet soil can lead to compaction, a problem that could affect plant growth throughout the season.

As dormant periods end, it's time to fertilize fruiting plants such as grapes, raspberries, and blueberries.

For those who haven't yet started their indoor seedlings, now is the time to plant seeds of broccoli, early cabbage, cauliflower, celery, eggplant, and head lettuce. Pepper seeds are also ready for indoor sowing, while tomato seeds should be planted indoors around the third or fourth week of the month.

Conduct a soil test to optimize conditions for the upcoming growing season. Your local Extension Agency can provide guidance on how to do this.

Begin acclimatizing cool-season crops like onions and parsley, which have been growing for at least five weeks, to outdoor conditions. When choosing transplants for cole crops, opt for younger, smaller plants, as larger ones may prematurely bolt if exposed to cold temperatures early in the season.

Outdoor seed sowing can commence for a variety of crops, including asparagus, beets, carrots, chard, kohlrabi, leaf lettuce, mustard, onion sets, parsnips, peas, potatoes, radish, spinach, and turnip.

Take advantage of workable soil conditions to establish new plantings of grapes, strawberries, raspberries, asparagus, and rhubarb.

For raspberries, prune this year's fruit-bearing canes back by one-quarter to stimulate growth. If you didn't already remove last year's canes after fruiting, now is the time to cut them to ground level.

MAY

Indoor seed starting is still an option for a variety of plants; this includes initiating the growth of Brussels sprouts, okra, pumpkin, cucumber, winter squash, melons, eggplant, peppers, and tomatoes within your home. It is advisable to plant vine crops like cucumbers and squash in individual peat pots, as they tend to suffer when transplanted due to root disturbance (Zone 5 - Monthly Garden Calendar: Chores and Planting Guide).

Direct seeding into your outdoor garden is suitable for a range of vegetables and root crops such as beets, carrots, chard, kohlrabi, late-season cabbage, various lettuces, mustard greens, collards, turnips, radishes, spinach, onions (both sets and seeds for bunching varieties), peas, and potatoes. Now is also the optimal time to enhance your landscape with new trees and shrubs.

Regular inspections of fruit trees, particularly ornamental crabapples and cherries, are crucial to detect infestations of Eastern tent caterpillars. If you find these pests, which appear as clusters of tiny, hairy caterpillars, it's important to either remove them by hand or prune the affected branches to prevent further damage.

Potato plants benefit from a technique known as "hilling," which should be done periodically to ensure a healthy crop. As outdoor temperatures stabilize, it's also time to begin acclimating plants that were started indoors to the outdoor environment. This process, known as hardening-off, involves gradually exposing plants to outside conditions to reduce transplant shock.

Perennial flowers should be fertilized as they begin their growth cycle, although they typically require this boost only once every three years and specifically during this early growth phase.

When the weather forecast is favorable, you can sow seeds directly outdoors for beans, okra, pumpkin, sweet corn, and watermelon. For a continuous harvest, plant only partial rows of beans and sweet corn, spacing out additional plantings every week or two. Sweet corn, in particular, benefits from being planted in paired rows or blocks to ensure adequate pollination.

As the month progresses and the threat of frost diminishes, it becomes safe to transplant a wider array of plants outdoors. This includes tender annual flowers like impatiens, as well as

JUNE

To safeguard your Brassica plants from the destructive cabbage moth and flea beetle, it's advisable to utilize a floating row cover, particularly if these pests have been an issue previously.

For tomatoes, it's beneficial to set up a trellis system early on to support the plants as they grow and prevent them from sprawling uncontrollably.

When dealing with Colorado potato beetles, which are identifiable by their yellow and black stripes, it's effective to manually pick off the adults, eggs, and red, humpbacked larvae found on the stem tips or the undersides of leaves. Spinosad, an organic pesticide, can be applied in severe infestations. These pests are likely to be around for the entire growing season.

Striped and spotted cucumber beetles are another concern as they can spread bacterial wilt to squashes and melons. Regularly inspecting plants and hand-picking the adults and eggs can help manage these pests.

The Mexican bean beetle is another pest to watch out for. Protecting your crops with a floating row cover from the moment the seedlings appear can prevent infestation.

Aphids, which can be found in new foliage or indicated by sticky leaves covered in honeydew, are common with warm weather. Although the resulting black sooty mold looks concerning, it's not harmful to the plants. Aphids, however, can cause damage. A strong water spray can dislodge many aphids, and insecticidal soap can control them effectively, although multiple applications may be necessary.

Squash vine borer moths, recognizable by their orange and green coloring, lay eggs at the base of squash vines. To prevent damage, inspect the stems daily and remove the brown, button-shaped eggs by hand. Wrapping the lower part of the stems with aluminum foil or a floating row cover can deter egg-laying.

Lastly, once the soil temperature has increased, applying a 2 to 4-inch layer of organic mulch to your vegetable and flower beds, as well as around trees and shrubs, can help retain soil moisture, suppress weeds, and regulate soil temperature.

JULY

It's the right time to initiate the indoor seeding process for your autumnal garden. Keep a diligent eye on your tomato plants' foliage for any indications of leaf spot diseases, which can manifest as discolored patches on the leaves. It's also important to persist in your vigilance against pest insects, as previously outlined in the June schedule.

For your garden's flowers, both annual and perennial varieties, the practice of "deadheading" is highly beneficial. This involves the removal of wilted flower heads, redirecting the plant's energy towards the generation of new blooms, foliage, and root development, often resulting in a second wave of blossoming.

Flowering demands considerable energy from plants, particularly annuals. To support this process, applying fertilizer as the flowering commences can be very advantageous, providing the necessary nutrients for robust growth. A subsequent fertilization closer to the season's end can further enhance the plant's vitality.

Continuation of seed sowing is advisable through the month of July for a late harvest of various crops such as beets, bush beans, carrots, chard, Chinese cabbage, cucumbers, kohlrabi, and even corn. Utilize a pre-moistened potting soil mixture for covering the seeds, as it's less prone to forming a crust or cracking. To maintain adequate moisture levels, lightly mulch the rows or employ a floating row cover fabric.

AUGUST

Keep planting seeds for a second harvest of root and leafy vegetables until August 15th, including beets, bush beans, carrots, Chinese cabbage, cucumbers, kohlrabi, and onion sets. It's also the right time to plant another round of peas and collards.

Maintain vigilance for pests and continue your routine checks for any damage they may have caused. Address any infestations or damage as necessary to protect your crops.

After you've picked the last of the raspberries, get a head start on next season's growth by pruning. Remove the old fruiting canes, ensuring you leave behind 3-4 of the younger canes for every foot of row to prevent overcrowding and disease. Hold off on trimming the tips of these canes until the spring.

Refrain from pruning trees and shrubs at this time; doing so could encourage new growth that won't survive the winter. Postpone any pruning until early spring when the plants are still dormant.

When your onions and garlic mature and their tops begin to dry and bend over, it's time to harvest. For garlic, braid the tops and hang them in a cool, dry place. Trim the onion tops down to 1 inch and allow them to dry completely before storage. Any onions or garlic that are damaged should be used right away.

Now is also an ideal moment to order and plant bulbs that will bloom in the spring, providing an early splash of color. Select varieties with staggered blooming periods to enjoy flowers for an extended time.

You can still sow seeds for a fall harvest of greens like leaf lettuce, mustard greens, Swiss chard, and spinach.

Lastly, continue to deadhead your flowering plants. This practice encourages them to concentrate their energy on producing a final flourish of blooms before the season ends.

SEPTEMBER

You can still sow seeds of leafy greens such as chard, spinach, and radishes, along with leaf lettuce, to reap a bountiful harvest before winter sets in. It's also important to remain vigilant for garden pests, especially as bean beetles may have a resurgence during this period.

As the season transitions, it's time to relocate houseplants that have been outdoors back inside. Before doing so, it's advisable to wash them thoroughly to dislodge any hitchhiking insects. While soil-dwelling bugs might not harm your plants, they could become bothersome indoors. Keep a close eye on these plants for the first few weeks indoors to catch and address any pest issues that may arise.

With winter approaching, consider mulching your garden beds. While bagged mulch is readily available, ordering mulch in bulk can be cost-effective, especially if you share the delivery with neighbors.

Perennials with fibrous roots typically benefit from being divided and transplanted every three to five years. For those that bloom in spring, autumn is the ideal time for this task. Pruning the plants back to four to six inches can help minimize stress from transplanting. Ensure that the new site is well-prepared to welcome these divisions.

Harvest pumpkins, summer squashes, and gourds before the first frost arrives. Even if pumpkins aren't fully mature, they will continue to ripen post-harvest if they've started to change color. Handle them carefully to avoid damaging the rind, which can hasten decay.

Continue to gather the yields from a second round of cool-season crops, including radishes, lettuce, Chinese cabbage, chard, spinach, broccoli, and other cole crops. Some vegetables, like parsnips, peas, Brussels sprouts, and kale, may even taste better after experiencing a light frost.

OCTOBER

Sow garlic, shallots, and other perennial alliums in your garden. Before the arrival of the initial hard frost, ensure that you've emptied out hoses and bird baths to prevent damage from freezing. For potted perennials that need to endure the cold season, consider burying them in a vacant section of your vegetable plot or insulating them with a generous layer of straw.

Now is the optimal time to gather soil samples for analysis, which will guide your fertilization strategy for the coming year. It's important to take individual samples from different sections of your landscape, such as your lawn, vegetable garden, shrubbery, and flower beds, especially if these areas have varying sunlight exposure or topography, like a shaded, sloping lawn versus a sunny, flat one.

For perennials that bloom in spring and summer, proceed with division and transplantation now. Those that flower in late summer or fall should be divided in spring instead. Trim back the foliage, replant the divisions, and water thoroughly. Hold off on applying fresh mulch until the coldest part of winter sets in, to give them ample protection during their first winter season.

Monitor the local weather forecasts and plan to harvest any remaining warm-season crops such as beans, eggplants, peppers, and tomatoes before a hard frost threatens to damage them.

Enhance your garden's soil by spreading a blend of manure, decomposed sawdust, composted straw, and shredded leaves, and then work these materials into the soil. This addition of organic matter can significantly improve soil fertility, structure, and moisture retention.

Before the growing season ends, take the time to harvest herbs, and either dry them or freeze them for future use.

After asparagus fronds have turned yellow and died back, cut them, chop them up, and add them to your compost pile. It's best to apply mulch to these beds once the soil has thoroughly frozen over.

NOVEMBER

Before the winter sets in, ensure that your plant containers are devoid of soil, scrubbed clean, and stored in a location that remains dry throughout the cold season. In the case of rain barrels, it's crucial to drain them completely and invert them to prevent any water accumulation, which could lead to damage during freezing temperatures. Reconnect your downspout to ensure that winter precipitation is channeled away from your home's foundation, as suggested by Butler SWCD.

Your garden can still flourish with certain crops during the chillier months. Frost can actually enhance the sweetness of cole crops, such as Brussels sprouts, cabbage, broccoli, collards, and kale. Keep these plants in your garden and continue to harvest them for as long as you can. To further extend their growing season, consider installing a low tunnel over these crops for added warmth and protection.

For tender late-season vegetables like carrots, beets, leeks, rutabagas, turnips, winter radishes, chard, Chinese cabbage, and leaf lettuce, it's beneficial to leave them in the ground. Protect them with a substantial layer of straw to insulate against the cold. For leaf lettuce, first lay down a floating row cover fabric to keep the straw from mixing with your greens, while still allowing the plants to breathe.

As long as the soil has not yet frozen, you can continue to plant spring-flowering bulbs. This is your last chance to get them in the ground before the freeze.

Regularly inspect your houseplants for any pests that may have hitched a ride indoors when you moved them inside for the season.

Once the soil has frozen to a depth of at least one inch, it's time to apply a protective mulch layer, around 2 to 4 inches thick, to safeguard your garden beds.

Lastly, it's the perfect time to service your gas-powered garden tools, such as lawn mowers and leaf blowers. With repair shops currently in their off-peak season, arrange for maintenance, tune-ups, and blade sharpening before the onset of snow when snowblowers will be in high demand for repairs.

DECEMBER

Holiday gift-giving can be both meaningful and beneficial when you opt for gift memberships to botanical gardens, arboretums, or nature centers. These gifts not only delight recipients with experiences that last throughout the year but also provide invaluable support to these treasured institutions.

To safeguard the delicate trunks of juvenile trees during the winter, wrapping them is a wise precaution. For trees and shrubs with multiple stems or low-lying branches, a barrier of chicken wire or hardware cloth, buried firmly at the base and tall enough to deter rabbits, is recommended.

Maintaining your gardening tools is crucial for their longevity. A thorough scrub with a wire brush followed by a light oil application can prevent rust. Hoes and spades benefit from a good sharpening, while pruning tools should be cleaned, adjusted, and sharpened. Wooden handles can be preserved with a light sanding and a linseed oil application or painted in vibrant colors for easy identification in the garden.

Mulching is an essential winterizing step for your garden beds, particularly around perennials. An appropriate mulch layer will provide insulation against cold temperatures.

For root vegetables like potatoes, parsnips, carrots, as well as herbs such as parsley and leeks, a generous covering of straw can extend the harvest period by providing frost protection.

When it comes to de-icing, it's important to choose materials that are less harmful to plants. Avoid rock salt and instead use products containing calcium chloride or potassium chloride. For added traction without excessive environmental impact, consider using sand, kitty litter, or wood ashes in moderation, possibly combined with a de-icing agent if necessary. Always use these products sparingly to minimize runoff pollution into our waterways.