There’s something a bit magical about May if you’re growing tomatoes — everything is waking up, the light is warmer, and your little seedlings are ready to hit their stride. If you want fat, juicy tomatoes this summer, May is the month to set the tone!
Here are three key things you should be doing right now:
- Harden Off Your Plants Properly
If you’ve been raising tomatoes indoors or in a greenhouse, May is not the moment to rush them outside permanently.
Tomatoes need to be hardened off — meaning, slowly introduced to outdoor life.
- Start by putting your plants outside for a few hours a day in a sheltered, warm spot.
- Gradually increase their outdoor time over 7–10 days.
- Bring them in if there’s a cold snap — tomatoes are drama queens about chilly nights.
Hardened-off plants are stronger, less stressed, and way more likely to flower and fruit heavily later.
- Feed Early — But Not Too Much
By May, your tomatoes are hungry. They’ve burned through the nutrients in their starter compost and are getting ready to power up with leaves and flowers.
- Start feeding once a week with a balanced fertilizer (equal parts nitrogen, phosphorus, potassium — look for an “all-purpose” or “grow-more” feed).
- Don’t jump too early into “tomato-specific” feeds (which are high in potassium) until your plants actually start flowering.
- Keep it light and regular — overfeeding now = lush leaves, but no tomatoes later.
Water first, then feed. Tomatoes absorb nutrients better when their roots aren’t dry and stressed.
- Watch the Weather and Support Early
May weather can be unpredictable — warm and breezy one day, wet and windy the next.
- If you’re planting out, stake or cage your tomatoes as soon as they go into the ground or a pot. Don’t wait until they’re big — by then it’s messy and risks damaging roots.
- Keep an eye on the night temperatures. If it’s dipping below 10°C, throw over a fleece, cloche, or even an old sheet at night.
- Remember: wind is just as bad as cold. It bruises stems and dries plants out fast.
If you see your young tomato flowers starting to form this month, give the plant a gentle shake — it helps pollinate early blooms and boosts your first fruit set.