May Cool-Region Kitchen Garden Almanac

The weather in cool northern regions can remain unsettled even in May. Remeber that both the soil and air temperatures are important when planting the kitchen garden. Few seeds will germinate if the soil temperature is below 45ºF (7ºC), and warm-weather crops are not going to thrive until the night temperatures consistently stay above 50ºF.

By the end of the month–or two to three weeks after your last frost, your kitchen garden will be able to welcome cucumbers, bush and pole beans, and tomatoes. In the meantime you can get these crops going in a greenhouse or coldframe or in the kitchen window. If you get the seedlings growing now, you’ll enjoy an earlier harvest next summer.

Strawberries can be planted now. June-bearing-type strawberries are vigorous and spread runners rapidly and should be producing in June. Everbearing-type strawberries will fruit in June and again later in the fall. If you are looking for the easiest to grow, try Alpine strawberries.

Cool-weather crops such as peas should be ready for harvest later this month or in June before the weather warms. Keep you eye on cauliflower and Brussels sprouts to get them out of the garden at their peak and before they bolt in warm weather.

Here is a kitchen garden guide for cool regions–growing zones 3-6–for the month of May.

Greenhouse and coldframe.

□ Open the greenhouse and coldframe for warm rain and sun; close them if the temperature drops near freezing.

□ Early in the month, sow under cover half-hardy annual seeds: tomato, eggplant, pepper, and runner beans. Plant greenhouse tomato plants and cucumbers in large pots or grow bags.

□ Harden off vegetable starts in the cold frame for 10 days before setting them out. By the middle of the month, you can harden off tomato plants and ready them for setting out late in month.

□ Harvest asparagus and other early crops from the coldframe.

□ Introduce biological controls to keep down pests such as greenhouse whiteflies and spider mites.

Vegetables early in the month.

□ As soon as the ground can be worked, add soil amendments, humus, and manure to the planting beds if these were not added in the fall. Prepare beds for planting and sowing.

□ Warm up the soil in cool regions with cloches or black plastic.

□ When the danger of heavy frost is past, sow or plant out cool-weather crops; harden off young plants from winter sowings of broccoli, cabbage, cauliflower, leeks, onions, lettuce, peas, and broad beans before planting out.

□ Start sowing vegetables without protection if you live in mild regions. Many seeds can be sown from early spring onwards. Check seed packets as some varieties are more suitable than others for early sowing.

□ Direct seed broad beans, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, kohlrabi, leeks, lettuce, onions, parsnips, peas, radishes, and spinach.

□ Plant asparagus, rhubarb, and celery. Dig well-rotted manure into celery trenches.

□ Prepare runner-bean trenches by digging in compost or well-rotted manure.

□ Plant early potatoes and onion sets.

□ Use horticultural fleece or cloches for early crops.

□ Thin out overcrowded vegetable seedlings sown earlier: thin beets, carrots, lettuce, radishes, and spinach.

□ Mulch after the soil has warmed and plants are several inches high.

□ Put supports in place for peas.

□ Turn compost pile.

Vegetable starts and transplants.

□ Protect vegetable starts from drying winds and keep them well watered.

□ Shade transplants from direct sun for a week or until re-established outdoors.

□ Mulch when plants are several inches high.

□ Weed and water as needed.

□ Watch for insects and signs of disease.

Succession planting.

□ Make a second sowing of early peas and other crops as the first harvest comes in.

□ Feed lettuce and other early crops with compost tea.

Vegetables late in the month.

□ Plant warm-weather crops and tender herbs when the danger of frost is past and the soil has warmed up and the weather settled. Sow seeds of beans, corn, okra, squash, cucumber, cantaloupe–all tender vegetables–when the weather has warmed into the 70s. □ Set out plants of tomato, eggplant, pepper, and sweet potato.

Fruits and berries.

□ Plant fruit trees and brambles when soil workable. Paint white or wrap trunks of young trees to prevent sunscald.

□ Water new plantings deeply if the weather is dry.

□ Feed summer-fruiting plants with potassium sulfate to promote good flowering and fruit.

□ Plant new strawberries, and place cloches over strawberries if you want an early cop. Be sure to cover strawberries if a late frost is possible.

□ Plant currant bushes and raspberry canes, and water them in thoroughly. Cut the canes down to 12 inches above the ground.

□ Thin brambles (blackberries, raspberries, loganberries); prune away weak shoots. Prune back the stems of newly planted and two-year-old gooseberries by about one-half. Spray gooseberries and black currants for gooseberry mildew.

□ Fertilize or top-dress with compost established berries and grapes if not done last month. Feed blackberry and hybrid berry plants with ammonium sulfate. Control weeds around bush and cane fruit.

□ If fruit trees are still dormant apply dormant spray to apples, pears, and plums.

□ Thin the fruit on apples, pears, and plums when marble-size. Thin heavy-cropping nectarines and peaches when the fruit is ½ inch (1-1.5 cm) in diameter.

□ Replace mulches removed last month.

□ Prune suckers and water sprouts from trees.

□ Watch for pests and signs of disease. Trap larvae on trunks of trees and destroy them.


□ When frost danger is past, move containers outdoors again.

□ Plant cool-weather and later warm-weather vegetables in containers when the danger of frost is past. Feed new plants with liquid fertilizer.

Growing tips for all veggies at the HOW TO GROW Archive: click here.

Regional Vegetable Gardening Tips for May:

These suggestions are divided into 4 major geographical areas: North and East and Midwest (zones 2 in the northern most areas to 6 along the coast), the South (zones 7 in the north to 10 in the far south), the Southwest and California (zones 7 in the coolest areas to 11), and the Northeast (zones 5 in the highest elevations to 8 along the coast).

North and East and Midwest.

□ Early in the month: Rush to get these crops in if you haven’t planted

□ Succession plantings of lettuce, beets, and carrots should be made from now until August, every 2 or 3 weeks, to provide a constant supply.

□ Set out any time during the month, successive starts of cabbage, broccoli, and cauliflower plants for late-season harvest.

□ Plants of tomatoes, eggplants, and peppers can go in the garden as soon as damager of frost is past. Harden off warm-weather starts before setting them in the garden.

□ Beans, corn, cucumbers, melons, potatoes, and squash may be planted in open ground in by mid-month, assuming the ground is not too cold. Sow bush beans 1 inch deep, 3 inches apart in rows 18 inches apart. Pole beans go into hills, 4 to 8 seeds to a hill; later thin to 2 or 3 plants.

□ Plant tomatoes in well-fertilized soil and strong supports. Work in phosphate and potash rock; tomatoes require little nitrogen. Keep tomatoes well watered.

□ Side dressings of complete fertilizer or aged compost will help along all young seedling plants.

□ If the season is mild, plant early corn. Add plenty of compost and a pound each of pulverized phosphate rock and potash rock to every 10 square feet of soil.

□ Early thinning of plants in rows is important–overcrowding will lead to poor development. Thin bush beans, 4 inches apart; beets 3 inches apart; carrots, 2 inches apart; chard 6-8 inches; corn, 10-12 inches; lettuce 6-10 inches; New Zealand spinach, 12-18 inches; onions, 2-3 inches; peas, 2-3 inches; radishes, 2 inches; rutabagas, 4-5 inches; spinach, 3-4 inches; turnips, 3-4 inches. Replanting thinnings is rarely successful.


□ Direct sow warm-weather crops: bush and pole lima beans, pole snap beans, cantaloupes, celery, collards, cucumbers, gourds, New Zealand spinach, okra, black-eye peas and crowder peas, pumpkins, rutabagas, squash, sunflower, turnips, and watermelon (if there is room). Sow a second planting of corn. Plant sweet potato slips, tomatoes, eggplants, collards, peanuts, and peppers. Plant cabbage for fall crop.

□ Plant seed of edible soybeans.

□ Cut okra pods before they mature, so the plants will continue to bear all season. Plant in wide rows with stalks every 2 or 3 feet.

□ Set out tomato plants. Plant 4 to 6 inches deep, water well and shade for 3 days. Pinch out suckers that develop between the main stalk and the branches while they are quite small. Prune to 2 stems. This will prevent them from utilizing plant food and making too much foliage. Stake with 5-foot stakes.

□ Stake tomatoes, eggplants and peppers when about one foot high.

□ Succession plantings: Set plants of eggplant, pimento, hot and sweet peppers where heads of cabbage, lettuce, mustard and other cool-weather crops have been harvested.

Southwest and California.

□ Plant warm-weather crops now: bush and pole beans, lima beans, beets, cabbage, cantaloupes, casaba, cauliflower, celery, chard, sweet corn, Chinese and Armenian cucumbers, eggplants, gourds, leaf lettuce (in shade), lima beans, melons, New Zealand spinach, okra, peppers, pumpkins, radish, salsify, squash tomatoes. Train Chinese and Armenian cucumbers, pole beans and tomatoes on stakes.

□ Plant heat-loving vegetables in deeply composted holes: lima beans, summer squash, peppers, eggplant, and tomatoes.

□ Tomatoes: a trellis-supported tomato will be more productive than one that sprawls on the ground. Set a trellis before the plant is in the ground more than 3 weeks. Train each branch as it grows. Tie stems in loosely so as not to cut into the branch. Set tomatoes deeper in the garden than they were in the seedbed.

□ Make successive plantings of vegetables every 10 days.

□ Watercress can be planted in shallow tub. Leaf lettuces can be planted in the shade.

□ Plant summer cover crops of the drought-resistant legumes: tepary and black-eye beans.

□ Mulch heavily with compost to help retain soil moisture and improve soil tilth.

□ Irrigate thoroughly once a week. Gently dig around roots to see if plants have sufficient moisture. Water at the base of plants.

□ Don’t work with beans or tomato vines when they are wet. Fungal diseases are easily spread in drops of water.


□ All plants may be set out as soon as the last frost date has passed: cabbage, cauliflower, cucumbers, peppers, and tomatoes.

□ Plant cabbage, cauliflowers, Brussels sprouts and kale before mid-month.

□ Direct seed pole and bush beans and midseason sweet corn. Sow pumpkin and squash toward end of month.

□ Make successive plantings at 10-day intervals.

□ Plant potatoes in well-drained, fertile soil.

□ Thin plants already in garden, and continue cultivation and weeding.

□ Stop cutting asparagus after the middle of the month.E

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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How To Grow Zucchini and Summer Squash

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