What to Plant in January: First Indoor Sowings and Which Seeds to Order Before February Sells Out
January is the planning and sowing month for US gardeners. Discover what to plant in January by USDA zone, which seeds to start indoors now, how to read a seed catalogue, and why chitting potatoes gives you a head start on the growing season.
Open your mailbox in January and the seed catalogues will have beaten you to it. While most of the country sits under frost, the gardening year has already begun — at the potting bench, on the windowsill, under the grow lights. January is not a waiting month. It is the month you plan, sow, order and prepare so that come April and May you are not scrambling to catch up. For US gardeners, the action depends entirely on your USDA Hardiness Zone: Zone 3–5 gardeners are firmly indoors; Zone 8–9 growers are already harvesting cool-season crops. This guide covers what to plant in January across every zone, what to sow on a windowsill right now, how to read a seed catalogue, why you need to start chitting your potatoes, and everything else that belongs on the January to-do list.
If you are planning your entire growing year, see our complete Year-Round Planting Guide for a month-by-month overview. For winter gardening tasks beyond seed-starting, the What to Plant in Winter guide covers cold-hardy crops and outdoor strategies for the coldest months.
January Gardening by USDA Zone: What to Expect
January looks dramatically different depending on where you garden. The USDA Plant Hardiness Zone Map divides the US into zones based on average annual minimum temperatures, and those temperatures determine what is possible outdoors. Here is the January reality zone by zone:
| USDA Zone | January Temperatures | Outdoor Planting | January Focus |
|---|---|---|---|
| Zone 3 (e.g. northern Minnesota, Montana) | −40°F to −30°F minimum | Nothing — ground frozen solid | 100% indoor seed-starting and planning |
| Zone 4 (e.g. northern Michigan, Vermont) | −30°F to −20°F minimum | Nothing outdoors; cold frames buried in snow | Indoor sowing: sweet peas, onions, celery |
| Zone 5 (e.g. Chicago, Indianapolis) | −20°F to −10°F minimum | Nothing; ground frozen | Seed orders, planning, indoor starts late January |
| Zone 6 (e.g. St. Louis, northern Virginia) | −10°F to 0°F minimum | Cold frames only — mache, spinach, kale | Begin indoor sowing: onions, sweet peas end of month |
| Zone 7 (e.g. Oklahoma City, Tennessee) | 0°F to 10°F minimum | Cold frames: brassicas, spinach, mache, claytonia | Direct sow cool-season greens under cover |
| Zone 8 (e.g. Seattle, Georgia coast, Dallas) | 10°F to 20°F minimum | Direct sow outdoors: spinach, kale, chard, peas, fava beans | Outdoors and indoors — active planting month |
| Zone 9 (e.g. Houston, Phoenix, central California) | 20°F to 30°F minimum | Broccoli, cabbage, cauliflower, beets, carrots, lettuce | Major planting month for cool-season crops |
| Zone 10 (e.g. Miami, southern California, Hawaii) | 30°F to 40°F minimum | Tomatoes, peppers, cucumbers, beans, squash | Plant warm-season crops — spring has effectively arrived |
For gardeners in Zones 3 through 6, the real action in January happens on the windowsill and under artificial lights. The following sections cover exactly what to sow now and why timing matters.
Seasonal Garden Calendar
Know exactly what to plant, prune and sow — every month of the year.
What to Sow Indoors in January
The crops that need to be started in January are slow growers. They share one characteristic: they require 10 to 14 weeks from seed to transplant-ready size, meaning that if your last frost date is in late April or May, you need to start them now. Do not wait until February — by then you are already two to four weeks behind on these crops.
Sweet Peas
Sweet peas (Lathyrus odoratus) are the number one crop to sow in January, and the reason is their tap root. Sweet peas develop a long, fragile tap root early in their growth, and if that root circles the bottom of a small pot it becomes kinked — stunting the plant permanently. The solution is deep containers: toilet roll tubes, root trainers, or purpose-made sweet pea tubes at least 6 inches deep. The tap root grows straight down without restriction, and when you plant out in spring the whole tube can go in the ground (cardboard tubes biodegrade).
Sow two seeds per tube, 1 inch deep. Place on a bright, cool windowsill — sweet peas prefer 50°F to 60°F and do not need warmth to germinate. Nick the seed coat with a nail file or soak seeds overnight before sowing to speed germination. Thin to one seedling per tube once established. According to the University of Minnesota Extension, cool-grown transplants resist transplant shock better than those raised in warm conditions.
Onions from Seed
Growing onions from seed rather than sets (small bulbs) gives you access to a far wider range of varieties — red Italian types, long-day sweet onions for the north, torpedo-shaped Rossa di Tropea — but it demands patience. Onion seedlings need 10 to 12 weeks indoors before they are large enough to transplant outdoors, which is why January is the only viable start month in Zones 3 through 6. Penn State Extension recommends sowing onion seeds in late January in the mid-Atlantic and Northeast to hit a late-March to early-April transplant window.
Sow thinly in trays filled with a fine seed-starting mix, just covering the seeds with a thin layer of vermiculite. Onions are notoriously slow to germinate — allow 10 to 14 days at 65°F to 70°F. Once up, keep them under grow lights or on the sunniest windowsill you have. Trim the tops with scissors when seedlings reach 5 inches tall — this encourages thicker stems. Plan for 60 to 70 plants per 10-foot row to justify starting from seed.
Celery and Celeriac
Celery and celeriac are the most demanding crops to grow from seed and the reason they must start in January. Both need 10 to 12 weeks indoors, but they are also notoriously slow to germinate — up to three weeks — and require consistent moisture and warmth (70°F) to do so. NC State Cooperative Extension classifies celery as a cool-season crop that needs an extended indoor growing period before hardening off. Surface-sow seeds without covering — they need light to germinate. Keep compost consistently moist using a misting bottle. Once germinated, grow on at 60°F to 65°F.
We cover this in more depth in seasonal march planting.
Celeriac (the knobby root vegetable, Apium graveolens var. rapaceum) follows exactly the same treatment but is somewhat more forgiving than regular celery. Both are worth starting in January because home-grown celeriac in particular is difficult to find in stores and produces far superior flavour to anything commercially available.
Chilli Peppers and Sweet Peppers
Peppers — both hot chilli types and sweet bell peppers — have the longest growing season of any vegetable commonly grown in the US. From seed to first harvest is typically 14 to 20 weeks depending on variety. Most pepper seeds require soil temperatures of 80°F to 85°F to germinate reliably, which means a heat mat is not optional — it is essential. Without bottom heat, germination can take four to six weeks and germination rates drop sharply.
Sow one or two seeds per cell in a 72-cell plug tray, covering lightly with vermiculite. Place on a heat mat set to 82°F. Once germinated (10 to 21 days), move immediately to bright light — grow lights are strongly recommended, as peppers grown on windowsills without supplemental lighting will become leggy. January-sown peppers will be 8 to 10 inches tall with several pairs of true leaves by transplant time in May, producing a much earlier and heavier harvest than later-sown plants.
Eggplant (Aubergine)
Eggplant follows the same protocol as peppers — heat mat, bright light, and a long indoor growing period. Sow at the same time as your chilli peppers. Eggplant is less forgiving of cold transplant conditions than peppers, so do not rush hardening off or transplanting outdoors. The extended indoor growing season produces plants with a strong root system that can fruit heavily before the first autumn frost.
Lobelia
Lobelia seeds are among the finest seeds in the garden — they look like specks of dust. Do not cover them at all; simply press the seed-starting mix smooth, scatter the seeds on the surface, and mist gently. Lobelia needs light to germinate and is extremely slow — allow 14 to 21 days at 65°F to 70°F. January sowing gives lobelia the 12 to 14 weeks it needs to develop into a full, flowering plant by the time outdoor containers are being filled in May. Pinch the growing tips once plants are 2 inches tall to promote bushy growth.
How to Read a Seed Catalogue
January is seed catalogue season. Baker Creek, Johnny’s Selected Seeds, Burpee, Botanical Interests, and dozens of specialist suppliers mail their catalogues — and many offer online browsing — precisely because growers need to order in January before popular varieties sell out. Knowing how to read a catalogue efficiently saves time and avoids disappointment.
Days to Maturity
“Days to maturity” (DTM) is the most important number in any vegetable catalogue entry. It counts the days from transplanting outdoors (for crops started indoors) or from direct sowing (for crops sown outside) to first harvest. A tomato listed at “75 days” will produce its first ripe fruit about 75 days after transplanting — not from seed. For Zones 3 through 5, always select shorter-season varieties with DTM under 75 for tomatoes and under 70 for peppers to ensure harvest before the first autumn frost.
F1 Hybrids vs Open-Pollinated Varieties
F1 hybrids are the result of crossing two parent lines. They offer hybrid vigour — often better yields, more disease resistance, and greater uniformity — but seeds saved from F1 plants will not breed true. Open-pollinated (OP) varieties, including heritage and heirloom types, breed true from saved seed. For gardeners who save seeds year to year, open-pollinated is the correct choice. For gardeners who buy new seeds each year and want reliability, F1 hybrids are often the better performer.
All-America Selections (AAS) Winners
The All-America Selections (AAS) programme is the closest US equivalent to the UK’s RHS Award of Garden Merit. AAS winners are trialled across dozens of test gardens across the US in multiple climate zones, and only varieties that demonstrably outperform existing varieties in those trials receive the AAS winner designation. When choosing between similar varieties, an AAS winner is a reliable indicator of above-average garden performance.
What to Order Now Before It Sells Out
Certain varieties sell out by February every year. Heritage tomatoes — Cherokee Purple, Green Zebra, Brandywine Pink, Black Krim — are reliably popular and stock is limited. Specialty peppers such as Aji Amarillo, Urfa Biber, and Jimmy Nardello sweet Italian frying peppers are in high demand. Unusual sweet pea colours — navy blue, chocolate maroon, striped bicolour types — from specialist growers sell out fastest. Order these now. Basic red tomatoes, standard sweet peppers, and mainstream marigolds will be available in March; rare and specialist varieties will not.
Chitting Potatoes: What It Is and Why It Works
Chitting means encouraging seed potatoes to sprout before planting. It is not strictly essential — you can plant an unchitted potato and it will grow — but chitting gives potatoes a two-to-four week head start, which is valuable in short-season zones and with maincrop varieties that need a long growing season. University of Minnesota Extension research on potato production supports early sprouting to optimise growing-season use in northern zones.
How to Chit Potatoes
Order your seed potatoes from a certified supplier — never use supermarket potatoes, which may carry disease and are often treated to prevent sprouting. When they arrive in January or early February:
- Place each potato rose-end up in an egg carton. The rose end is the end with the most eyes (dormant buds). Pointing it upward concentrates energy into the upper shoots.
- Put the egg carton in a light, frost-free location — a cool spare room, an unheated but insulated garage, a bright porch. Ideal temperature: 45°F to 50°F. Too warm and sprouts become long and weak; too dark and they etiolate (go pale and spindly).
- After three to four weeks you should have short, stubby, green-to-purple sprouts about 1 inch long. These are perfect chits. Long white sprouts indicate too little light.
- When planting time arrives (typically soil temperature 45°F, last frost two to three weeks away), keep one to three sprouts per potato and rub off the rest. Plant sprout-side-up.
What to Do Outdoors in January
Even in Zones 3 through 6, there are meaningful outdoor tasks on frost-free January days. Do not let the cold become an excuse to avoid the garden entirely — these tasks are best done now, before the rush of spring.
Prune Apple and Pear Trees
Winter pruning — carried out while the tree is fully dormant — is the correct time to prune apple and pear trees. Pruning now removes crossing branches, opens the canopy to airflow (which reduces fungal disease), and removes any diseased wood. NC State Cooperative Extension recommends pruning fruit trees on frost-free days between December and early March. Avoid pruning on days below 28°F as very cold wood is more prone to splitting. Make clean cuts just outside the branch collar using sharp, clean pruning saws or loppers.
Heel In Bare-Root Plants
If you have ordered bare-root roses, fruit trees, or hedging plants and the ground is still frozen when they arrive, heel them in temporarily. Dig a shallow trench in a sheltered, unfrozen spot, lay the roots in at an angle, and cover with soil or compost. This keeps roots moist and prevents them drying out or freezing. Plant in their final positions once the ground thaws — typically late February to March in Zones 5 through 7.
Protect Tender Shrubs
Marginally hardy shrubs — camellia, gardenia, banana, fig — may need protection in Zones 5 through 7 during January cold snaps. Burlap wrapping prevents wind desiccation and moderates temperature fluctuations. Avoid plastic wrapping (it causes overheating on sunny winter days). A thick layer of shredded bark mulch over the root zone provides insulation against freeze-thaw cycles that heave roots.
Check Stored Dahlia Tubers and Amaryllis Bulbs
Dahlia tubers lifted and stored in autumn should be inspected in January. Look for shrivelled tubers (too dry — mist lightly) and rotting sections (cut away cleanly with a sterile knife, dust with sulphur or cinnamon). Amaryllis bulbs in dormant storage should feel firm and show no soft spots. Bring amaryllis into warmth in January to trigger new growth for late-winter flowers.
Indoor Plants in January
January is an excellent time to give houseplants attention. Growth is slow due to low light levels, but root-bound plants can be repotted into fresh compost before the spring growth flush begins. This is especially valuable for fast growers like peace lily, spider plant, and pothos that may have been neglected over the busy summer. For more on growing herbs inside during winter months, see the Growing Herbs Indoors guide.
Repot Root-Bound Houseplants
Signs of a root-bound plant: roots emerging from drainage holes, soil drying out within 24 hours of watering, or the plant lifting itself out of its pot. Move up one pot size only — doubling the pot size leads to overwatering and root rot. Use a well-draining potting mix appropriate to the plant type. Water thoroughly after repotting and keep out of direct sun for a week while the plant settles.
Force Hyacinths and Paperwhite Narcissus in Water
Hyacinths and paperwhite narcissus (Narcissus papyraceus) can be forced in water — no soil required. Place the bulb in a forcing vase or glass with the base just touching water. Keep in a cool, dark spot for two to three weeks until roots develop, then move to a bright windowsill. Flowers appear four to six weeks later. Paperwhites are particularly easy, requiring no cold period, and their strong fragrance makes them one of the most rewarding January projects.
Start Citrus from Seed
Growing a citrus tree from seed is a long-term project (years to fruit, if ever) but an enjoyable one. Fresh seeds from a grocery-store lemon, lime, or orange germinate readily in warm compost at 70°F. The seedlings make attractive, fragrant houseplants regardless of whether they fruit. For fruiting plants, grafted dwarf citrus trees are a better choice — but the seed project is a satisfying January experiment, especially with children.
Seed Storage in January: The Cool, Dark, Dry Principle
January is also the moment to audit last year’s leftover seed packets and establish proper storage for the season ahead. Seeds deteriorate fastest in warm, humid conditions. The three principles of good seed storage are cool, dark, and dry — and the kitchen counter (warm and light-fluctuating) is about the worst place you can keep them.
- Cool: Store seeds in the back of the refrigerator (35°F to 40°F is ideal) or in a cool, dark cupboard. Freezing is possible for long-term storage of fully dry seeds but requires a sealed container.
- Dark: Opaque containers or envelopes prevent light degradation. A biscuit tin, a dark glass jar, or a seed storage box all work well.
- Dry: Add a silica gel desiccant packet to absorb moisture. Silica gel packets from shoe boxes or vitamin bottles can be dried in a low oven (250°F for 30 minutes) and reused indefinitely.
- Labelled: Always write the year of purchase (or harvest) on the packet. Onion and parsnip seeds lose viability quickly — use within one year. Tomato and pepper seeds remain viable for four to five years if stored correctly.
Test old seeds before sowing by placing 10 seeds on a damp paper towel, folding it over, and keeping it warm for the crop’s normal germination period. Count how many sprout: 8 out of 10 (80% germination rate) is fine; below 50% means sowing extra thick or buying fresh seed.
Where to Order Seeds in January
Two reliable suppliers with excellent range for US gardeners:
- Thompson & Morgan — Strong selection of sweet pea varieties, unusual annual flower seeds, and vegetable novelties. Their sweet pea range in particular is among the widest available to US growers.
- Crocus — Best known for bulbs and perennial plants, but their seed range includes excellent heritage vegetable varieties and specialist annual flowers. Particularly useful for unusual squash, heritage brassicas, and cutting garden annuals.
What to Sow in February
February brings the first real wave of indoor seed-starting for most US gardeners — brassicas, leeks, antirrhinums, and bedding plants all begin in February. For a full breakdown of what comes next, see the February Planting Guide. And for a complete overview of the entire growing year, the Year-Round Planting Guide maps every sowing and planting date from January through December.
Frequently Asked Questions
Can I plant anything outside in January?
It depends on your USDA zone. In Zones 8 and 9, you can direct sow cool-season vegetables — kale, spinach, chard, peas, fava beans, carrots, beets — directly outdoors in January. In Zone 7, cold frames extend the planting window for brassicas and salad greens. In Zones 3 through 6, outdoor planting is generally not possible; the ground is frozen and daytime temperatures are too cold for germination or growth. All January planting for these zones happens indoors.
What can I grow on a windowsill in January?
A bright south-facing windowsill in January can support sweet peas (which prefer cool conditions), microgreens (radish, pea shoots, sunflower), herbs including parsley and chives, and lettuce for cut-and-come-again harvesting. For heat-loving crops like peppers and eggplant, a windowsill alone is rarely bright enough — a grow light suspended 2 to 4 inches above the seedlings significantly improves results. Microgreens are the most rewarding windowsill crop because they go from seed to harvest in 7 to 14 days regardless of outdoor conditions.
When should I start seeds for summer flowers?
It depends on the flower. Sweet peas: January (10 to 14 weeks before last frost). Lobelia: January or early February (12 to 14 weeks). Snapdragons, petunias, and impatiens: late February to early March (10 to 12 weeks). Zinnias, sunflowers, and cosmos: do not start early — these fast growers do better direct-sown outdoors or started just 4 to 6 weeks before last frost. Starting zinnias in January produces root-bound plants that never fully recover. The NC State Cooperative Extension annual flower sowing calendar is a reliable reference for timing by crop.
Sources
- NC State Cooperative Extension — Annual Flower Sowing and Cool-Season Vegetable Production
- Penn State Extension — Vegetable Seed Starting Indoors
- University of Minnesota Extension — Growing Potatoes and Cool-Season Vegetable Production
- All-America Selections (AAS) — Trial and Testing Programme for Garden Varieties
