Mark Your Calendar: The Exact May and June 2026 Dates for Perfect Greenhouse Tomatoes
Moon-timed planting is back as the 2026 lunar calendar maps the best greenhouse windows to set tomato seedlings for a stronger, earlier crop.
Tomato time is coming, and the greenhouse is calling. If you like your planting schedule with a side of lunar strategy, here is a clean, practical guide to getting those seedlings in the ground at the right moment in 2026.
Set up the soil like you mean it
Tomatoes are a flagship greenhouse crop, and they pay you back when the bed is prepped well. Work in plenty of organic matter first: compost, well-rotted manure or humus, and vermicompost. Follow with mineral fertilizers, with extra attention to potassium. Strong stems and steady fruiting love potassium.
Waxing Moon = push for tops and branches
Because tomatoes set their fruit above ground, transplanting on the waxing Moon stacks the deck for vigorous stems and branching. This timing helps all seedlings, and it matters most if you are planting bare-root starts.
Container-grown seedlings get more flexibility
If your tomatoes come out of pots or cell trays with an intact root ball, you can plant on the waning Moon too. For that window, aim for days when the Moon moves through Taurus, Virgo, Capricorn, Cancer, Pisces, or Scorpio.
Best dates to transplant tomatoes into the greenhouse in 2026
- April: 13-15, 18-19, 21-30
- May: 3, 6-7, 11-14, 19-30
- June: 2-4, 7-9, 11-13, 17-26
That is your calendar. Prep the bed, keep potassium in the mix, and use the Moon to nudge growth in your favor. The greenhouse will handle the rest.