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Winter Gardening: December Checklist Zones 4-6

The shorter days of December provide gardeners in Zones 4-6 time to reflect on last season’s garden successes and disappointments, take care of garden tools and plan for the next year’s garden season.
If you’ve planned and planted a winter crop in a greenhouse, you’ve got some additional care and harvesting to think about.

While December is a leaner month for garden chores, there are still plenty of things that can be done throughout the month of December to help ensure a strong gardening season ahead. Check out our December garden checklist and make sure you don’t miss some essential steps, maintenance routines, and opportunities to dream big about next season’s garden.

Pink flower covered in frost

December Garden Planning

You can do plenty in USDA Grow Zone 4-6 when it comes to garden planning. When the days are cold, and the landscape looks rather bleak, it’s an ideal time to plan for next year’s crops. It’s time to look back at the delights and pitfalls of past seasons and forge forward with new ideas and enhancements for the coming year.

Garden Journal

This is an excellent time for starting a gardening journal if you don’t have one already. Chart seed and plant varieties, their planting specifications, days to germinate and mature, and keep notes about what worked well and what didn’t. This chart will help you plan from year to year with knowing when to sow seeds, plant with optimal spacing, when you can expect blooms, and when to harvest your plantings.

If some of your crops were plagued by pests or disease, it is a great time to research companion plants and spacing provisions that can protect and boost your plants’ production.

Garden Planning

At this point in the year, seed catalogs should start popping up in your mailbox. This is the perfect opportunity to sit back, get cozy, peruse the catalogs, and dream of what you’d like to plant in your spring and summer, and fall gardens. Take the time to embrace the possibilities for what you can grow within your garden space and decide if you need to carve out more garden beds or acquire new planters. Ordering seeds early can ensure that you get the seeds you seek before other gardeners snatch them up.

If you have friends or community members who are also passionate about gardening, you might look for a seed swap nearby or perhaps start one of your own. Often, whether through seed saving or an overflow of seeds in packets, you may have extra seeds. Add some diversity to your garden this year by swapping and sharing seeds with other gardeners. Embrace the opportunity to connect with other gardeners and try something new in the garden.

Take out your garden journal and dream a little. Sketch out some ideas or clip garden plan ideas out of magazines to give you visuals to aspire to. Perhaps there are even some indoor construction projects that you can do, like create a climbing structure or a raised bed to be added to your garden this spring.

Winter Garden Maintenance

Fall and winter garden maintenance will make things easier once spring rolls around. Here is a short list of tasks that will keep your garden happy throughout the winter months.

  • If you haven’t done so already, dump out any pots and store them in a garage or garden shed so that they don’t freeze and crack. You can also store them upside down if they need to be outside.
  • Cut back spent plants to about 6 inches and add non-diseased organic matter to your compost pile.
  • Cover your compost pile with a tarp or a couple of inches of straw before snowfall.
  • If a deep freeze has not yet set in, you can add compost to your gardens and plant cover crops. Both will help to enrich the soil and help combat erosion.
gardening tools on wooden white wall.

Garden Tool Cleanup

This is the ideal time of the year to maintain your garden tools to keep them in the best working order and to eliminate any disease that might be present upon them. Not only does tool cleaning and maintenance ensure that you have what you need for garden work, but it also will keep your garden free from diseases that may have plagued your garden last season.

  1. Start by using steel wool or a metal grill brush to clean any debris off your garden tools.
  2. Wipe surfaces with a damp rag.
  3. Use coarse sandpaper to scuff away any signs of rust on metal surfaces.
  4. Dab vegetable oil onto a rag and wipe metal surfaces.
  5. Use a piece of sandpaper to slough away any rough or splintering spots on wooden handles.
  6. Wipe wooden handles down with a rag wet with linseed oil.

Don’t forget to take inventory of the tools you have and the tools you need. Now is also a great time to shop for new tools as many garden centers have sales and promotions throughout the winter months.

Composting

Developing an ongoing composting system is one of the best things you can do for next year’s garden. Healthy gardens start with a robust and nutrient-rich soil structure. If you do not already have a compost pile, create one today and add to it all winter long.

A common question when starting a compost pile is, what can I compost? Organic food and natural green and brown items decompose together to create soil that is well-draining, high in nutrient content and filled with beneficial microorganisms. A rule of thumb for compost is to have 30-parts of brown ingredients, which are carbon producers, to 1-part green elements, which are the nitrogen producers.

If you experience harsher winters like in Zone 4 and Zone 5 then you may want to save some materials to add to your compost pile over the winter such as lawn clippings, brush, and leaves so that you have nutrient-rich compost come spring. Zone 6 may be able to continue to collect items from their lawn and yard throughout the winter. All three of these zones can also practice indoor composting.

Brown Composting Materials

  • Paper
  • Pine needles
  • Straw
  • Vegetable stalks
  • Wood shavings
  • Dry leaves

Green Composting Materials

  • Eggshells
  • Fruit and vegetable scraps
  • Grass clippings
  • Hair clippings
  • Alfalfa meal
  • Feathers
  • Coffee grounds

Mulching Your Garden

Mulch plays a vital role in the garden beds during the growing season, but it is also essential to add mulch in the fall and winter months. Mulch insulates the soil and protects perennial plant root systems. Warmer soil also helps microorganisms to thrive and remain active even during the coldest of seasons.

Snow is an excellent insulator for your perennials and overwintering crops as well. Still, you cannot always count on a consistent snow layer all winter long, so protection can be sporadic. Zones 4-6 can have frequent shifts in temperature as well. Inconsistent soil temperature that freezes and thaws and then freezes again can cause damage to root systems. Adding a thick layer of mulch can help regulate root and soil temperatures, adding much-needed protection.

Similar to composting, Zone 6 may be able to make their own garden mulch using leaves, lawn clippings, branches, brush, and sawdust. In Zones 4 and 5 gardeners may need to purchase mulch from a local garden center or nursery.

Seeds sprouting in a seed starting tray

Indoor Planting and Growing

While you are hunkered down for winter and dreaming of next year’s gardens, there are things that you can plant to keep you motivated for spring blooms and crop planting. While it might be on a smaller scale, you’ll be able to reap the rewards of some indoor edibles and ornamental pleasures.

Indoor Gardening

Beat those winter blues by forcing bulbs indoors. Watching these fragrant and beautiful bloomers emerge and flower brings a sense of hope and renewal to gardeners. Select a shallow dish or pretty bowl and place a layer of rocks or marbles and water in the bottom. Place narcissus bulbs root side down and watch and wait.

Another great bulb to plant indoors in the winter is the amaryllis. Nothing beats the large and vibrant blooms of this treasure of a plant in the winter months. The amaryllis requires very little maintenance and a huge reward.

December is also a great time to get a jumpstart on some indoor seed starting for seeds that require lengthy germination or maturation periods. Seed trays with covers and a sunny window or grow lights and warmers make growing seedlings indoors a breeze.

Don’t overlook the opportunity to grow planters of lettuce and herbs in a sunny area of your home. You can create a small indoor garden that will allow you to tend and snip greens and herbal accents all winter long.

Greenhouse Gardening

A greenhouse is an excellent option for extending the growing season for those in Zone 4-6. There are a lot of crops that can be successfully grown in a greenhouse in the wintertime. The structure just needs to be able to withstand heavy snow and plunging temperatures as it lets sufficient sunlight in and protects plants from harsh weather conditions. In Zones 4 and 5 you may need to insult or even heat your greenhouse more than in Zone 6 due to the harsher winters.

Root vegetables and greens are good performers in greenhouse environments during this colder season. Traditionally, some of these crops should have been planted in late summer and early fall for a winter harvest. To figure out the ideal planting date for a winter harvest, you must examine the days until maturity on the back of the seed packet and count backward from the time you want to harvest the crop.

When shopping for seeds, keep a keen eye out for winter garden vegetables that boast cold hardiness and have shorter maturation periods. This is particularly important, as shorter days of sunlight and cooler temperatures will increase the time it takes for plants to mature. Try planting carrots, beets, potatoes, turnips, kale, winter lettuce varieties, scallions, endive, parsnips, onions, radishes, parsley, and arugula as winter crops.

A winter crop won’t always be a successful one, so try not to lose heart. You can do some things to boost your chances of a successful winter crop within the greenhouse. Combining a couple of protective methods has been proven to show successful crop growth. Inside the greenhouse, deep mulching crops, adding heavier fabric row covers and hoop houses inside a greenhouse can help insulate crops further and boost heat retention if utilized before the soil freezes. Another method to take the edge off the winter chill is to create a compost pile inside of a greenhouse. As the organic material decomposes, it can boost temperatures slightly.

Outdoor Winter Garden Planting

If you’ve seen inspiring outdoor winter garden crops on social media, try not to get your hopes up too high. The ground in this climate is traditionally known for a deep freeze of the soil, which is not conducive to planting, growing, and harvesting vegetables and flowers from outdoor gardens in December especially in Zones 4 and 5. Zone 6 may be able to do some protected outdoor winter garden planting using cold frames.

Continue to set your sights on all of the things you can do on our garden checklist. Remember that with some planning, preparation, and a little creativity, you can bring your garden to an enhanced level for the upcoming growing season.

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Watering and Harvesting

With all other protective measures in place, the winter gardener’s primary job is to water and harvest their crops when December rolls around. Luckily, winter gardening doesn’t need much in the way of regular watering. Mulching and the reduction of available sunlight reduces watering needs considerably. There are also fewer weeds to rob moisture supplies from valuable crops.

When harvesting lettuce greens and herbs, try the ‘cut and come again method’ of harvesting. This method encourages the regeneration and continued growth of the plant over time. Other cold-hardy vegetables may be hardy enough to withstand freezes, but when it comes to harvesting these crops, they should be harvested when the soil is thawed. The ideal time for harvesting such crops is midday when the daily temperatures and sunlight are at their peak.

You’ve worked very hard to bring your winter crop from seed to harvest, so be sure to protect your pickings from the frigid air temperatures. Consider transporting your produce in a covered basket to protect the now tender vegetables from freezing and wilting.


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Pink flower covered in frost with text, "December Garden Checklist Zones 4, 5, and 6".
Seeds sprouting in a seed starting tray, "With text, "Winter Garden Activities Zones 4-6; composting, seed starting, mulching, garden planning".

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