Spring Garden Planting Guide: What to Plant and When

Spring is simultaneously the most exciting and most maddening time in the garden. What can go in the ground right now? What needs to wait another month? What should’ve been started indoors three weeks ago? I’ve been there, staring at seed packets in February like they’re written in another language. This guide walks you through the whole spring timeline so you don’t miss a single window.

The Frost Date Is Your Anchor

Seriously, everything comes back to this one number. Your last average frost date is the point in spring after which a killing frost is unlikely — and in the US, that window is huge. We’re talking late January in Southern California all the way to late May up in Minnesota. Find yours at the USDA frost date tool or just call your local agricultural extension office (they love these questions, truly). Once you’ve got that date, the rest of the timeline basically writes itself.

8-10 Weeks Before Last Frost: Start Indoors

Tomatoes, peppers, eggplant, and celery are the slow ones — they need a solid 8 to 10 weeks of indoor growing time before they’re anywhere near ready for the outside world. I start mine under a basic grow light setup, but a really sunny south-facing window works too if that’s what you’ve got. One thing I learned the hard way: use biodegradable pots or soil blocks from the start. Those tender roots do not like being messed with at transplant time, and anything that reduces that stress is worth it.

4-6 Weeks Before Last Frost: More Indoor Starts and Cold-Hardy Direct Sowing

This is actually my favorite phase because you get to go outside for the first time all season. Cold-hardy crops — peas, spinach, arugula, kale, radishes, beets — can go directly in the ground 4 to 6 weeks before your last frost. They don’t just tolerate a little cold, they actually like it. My husband was skeptical the first time I planted spinach in March with patches of snow still on the ground, but it came up just fine. Meanwhile, inside, you’re starting squash, cucumbers, and melons — but only 3 to 4 weeks out, not earlier. They grow fast. Trust me, give them too much head start and you’ll have sprawling chaos on your hands before it’s even safe to transplant.

2 Weeks Before Last Frost: Hardening Off

Hardening off sounds fancier than it is. All you’re doing is slowly introducing your indoor seedlings to real outdoor life — wind, direct sun, temperature swings — so they don’t go into shock when you plant them for good. Set them outside in a sheltered spot for a couple hours a day, then bring them back in. Add a little more time each day over one to two weeks. I actually tried skipping this step one impatient spring and lost half my tomato transplants to sunscald practically overnight. Never again. It takes a bit of babysitting but it’s honestly not a big deal once you get into the routine.

After Last Frost: Warm Season Crops

This is the moment you’ve been waiting for. Once your last frost date has passed, the warm-season crew can finally go in — tomatoes, peppers, squash, cucumbers, beans, corn, basil, all of it. That said, don’t rush it if nights are still dropping cold. Warm-season crops planted in cold soil don’t just grow slowly, they basically stall out. I’ve watched plants set out two weeks later in warmer soil completely catch up to — and pass — ones I planted too early in cold ground. A soil thermometer is cheap and it’ll save you a lot of frustration. Fifty degrees Fahrenheit is usually the minimum you’re looking for.

Final Thoughts

The first spring you try to follow this timeline, it feels like a lot to track. By your third year, you’ll be doing it on autopilot, probably already planning next year’s layout before this year’s tomatoes are even ripe. The whole system really does hinge on that one frost date — get that nailed down and everything else clicks into place. Your summer garden will absolutely show the difference.