From the Kitchen Garden: May, Summer Starts Now

May is when Riverside gardens really begin to shift gears. The cool-season crops are still producing, but the warmer days and mild nights are inviting in summer favorites. Right now, the question I'm getting asked most is: "Is it finally time to plant tomatoes and peppers?" The answer is yes — and they are loving this heat. My garden boxes are quickly filling with tomatoes, peppers, and squash, and everything is starting to take off with the longer days.

One of the best things you can do this month is focus on companion planting. I always tuck basil and onions alongside my tomatoes. Basil is said to enhance tomato flavor while also attracting pollinators, and onions can help deter certain pests in the garden. Pairing plants intentionally helps create a healthier, more balanced garden ecosystem and makes the most of every inch of space.

As warm-season crops go in, don't forget about succession planting. Instead of planting everything all at once, stagger quick-growing crops every couple of weeks to keep your harvest going longer. I'm continuing to add lettuce, cilantro, and peas where I have space so I can stretch the season before summer heat fully arrives. If you pull out a spent crop, try not to leave bare soil behind — open soil invites weeds quickly this time of year. Pop in a fast-growing herb, flowers for pollinators, or another round of greens to keep your beds productive and healthy.

This is one of the most exciting months in the garden. Everything feels full of possibility.

What Are We Picking?

Vegetables: Lettuce, kale, Swiss chard, carrots, radishes, beets, green onions, finishing broccoli, cauliflower, and snap peas

Herbs: Rosemary, thyme, oregano, parsley, cilantro, sage, lemon balm

Flowers: Pansies, snapdragons, calendula, sweet peas, stock, larkspur, nasturtium, salvias

Fruits: Strawberries, blackberries, and if you are one of the lucky few… the beginnings of nectarines and peaches!

What Are We Planting?

May is the beginning of warm season in Riverside. It's finally time to start filling beds with heat-loving summer vegetables that thrive as temperatures rise.

Plant now: Tomatoes, peppers, squash, cucumbers, beans, lettuce transplants, spinach transplants, arugula, cilantro transplants, onions, garlic, potatoes, and snap peas.

Don't forget to mix herbs in with your other vegetables — herbs are big pest deterrents, so intermix them throughout your beds. I'm adding thyme, rosemary, basil, and oregano, but you might also consider a tea garden. Lemon balm, lemon verbena, lemon thyme — yes, that's a lot of lemon, but it is so good! Other great tea herbs are chamomile, pineapple sage, and mint. (Keep mint in its own closed-bottom pot, or it will take over your garden.)

What to Watch Out For

Aphids on New Growth — As temperatures rise, aphids quickly appear on tender growth, especially on tomatoes, peppers, lettuce, and herbs. You'll often find them clustered under leaves or along stems. Solution: Spray plants with a strong stream of water every few days or use insecticidal soap. Encouraging ladybugs and hoverflies naturally helps keep populations under control.

Powdery Mildew — Warmer days combined with cool evenings can create conditions for powdery mildew on squash and cucumbers. Look for white, dusty patches forming on leaves. Solution: Improve airflow by spacing plants properly, avoid overhead watering, and remove infected leaves early before it spreads.

Snails, Slugs, and Rollie Pollies — All three are active in irrigated gardens and love tender greens and strawberries. Solution: Hand-pick at dusk, use beer traps or slug bait, and avoid letting mulch pile directly against plant stems.

Gardener's To-Do List

• Amend garden beds with 1–2 inches of compost to replenish nutrients before summer growth takes off.
• Check irrigation systems for leaks or clogged emitters and consider installing timers before hotter weather arrives.
• Water tomatoes, peppers, and squash deeply every other day as temperatures begin climbing.
• Add mulch around plants to help regulate soil temperature and reduce water evaporation.
• Fertilize citrus trees with a citrus-specific fertilizer and water deeply afterward.
• Continue succession planting lettuce, cilantro, and peas or beans every couple of weeks for continuous harvests.
• Get your RPU free tree planted!

Closing Tip

Riverside's long growing season is one of our biggest gardening advantages. You don't have to rush to plant everything at once — slow, steady planting often creates the healthiest and most productive gardens.

Pro tip: Companion planting really shines this time of year. Try pairing basil with tomatoes and onions throughout your beds to help naturally support pollinators and reduce pest pressure while maximizing your growing space. 🌿

A few more companion pairings worth trying this month:

Squash + Nasturtiums — Nasturtiums act as a trap crop, attracting aphids away from squash plants. Their flowers also bring in pollinators, which helps improve squash production.

Peppers + Marigolds — Marigolds help repel nematodes and attract beneficial insects like hoverflies and ladybugs. Peppers benefit from reduced pest pressure and increased pollination activity nearby.

Cucumbers + Dill — Dill attracts pollinators and beneficial predatory insects that help control cucumber pests. Cucumbers provide a living trellis around the dill while benefiting from increased insect activity.

More information: Kim Malstrom designs, installs, and teaches vegetable gardens for beginners and families in Riverside. To learn more, visit kitchengardensbykim.com or follow along on Instagram at @kitchengardensbykim.