❑ If you haven’t already, begin seeding tender plants such as eggplants and sweet peppers indoors. Plant tomatoes indoors at the end of the month.
❑ Outdoors, plant potatoes, peas, spinach, lettuce, beets, onions and Asian greens.
❑ Transplant or direct-seed cole crops such as broccoli, cabbage, cauliflower and Brussels sprouts.
❑ Start adding compost to your soil. Compost should be in place before planting anything outdoors.
❑ Remove remaining protective winter mulch from perennial beds, trim out old foliage and apply mulch for summer as soon as true leaves develop. Mulch will conserve moisture and help prevent weeds.
❑ Cover seedlings and transplants with agricultural fleece to protect from birds.
❑ Expect roller-coaster temperatures. Don’t get impatient and plant outside too early.
❑ Plant bare-root roses and trees.
❑ Shear back groundcovers and wake up your flower beds with a general fertilizer.
❑ Protect tender plants from frost.
❑ When forsythia blooms, prune roses and apply corn meal gluten or another crabgrass pre-emergent to lawn.
❑ Fertilize roses after pruning.
❑ Plant conifers and shrubs. Also plant summer bulbs: Alliums, cannas, Hostas and daylilies.
❑ Prune buddleias, shrub dogwoods and caryopteris.
❑ Begin hardening off indoor seedlings to acclimate them to outdoor life. Shelter tender seedlings from wind.
❑ Watch for aphids and knock them from plants with a blast of water. Beneficial insects will take over soon.
❑ Set up supports for peonies, delphiniums and other “floppers.”
❑ Deadhead (remove spent blossoms from) tulips, daffodils and crocuses. Don’t remove foliage until it’s yellow or brown.
❑ Continue pruning spring-flowering shrubs immediately after they have bloomed.
❑ Local lore says that when the snow is melted off Shafer Butte north of Boise, it’s safe to plant most annuals outside. May 10 is the average last date of frost in the Treasure Valley.
❑ If you haven’t fed your roses, do it now.
❑ In early May, direct seed corn; in late May, cucumbers, beans, squash, other warm-weather vegetables and melons.
❑ Feed your lawn with 1/4 of its annual fertilizer allotment, unless you’re using a mulching mower.
❑ Plant annuals to fill in perennial beds and conceal yellowing foliage of spring-flowering bulbs.
❑ Prune lavender to shape after it shows signs of new growth.
❑ Plant out seedlings of peppers, tomatoes, eggplants and basil. Watch for late frosts.
❑ Stop feeding trees by June 15, to allow them to progress toward winter dormancy.
❑ Tackle weeds regularly and frequently so you keep a handle on the situation. Remember, mulch also keeps weed seeds from germinating.
❑ Feed roses.
❑ Monitor lawn. When it gets a bluish cast and footprints don’t bounce back readily, water deeply.
❑ Keep your eye out for destructive insects; if necessary, use the least toxic controls first.
❑ Dig and separate iris, afte bloom.
❑ Prune “candles” from needled evergreens to control growth.
❑ Plant short-season beans, beets, carrots, collards, radishes, cabbage, broccoli and similar plants for second harvest in fall. Plant spinach later.
❑ Make sure you are watering trees deeply.
❑ Thin fruit and do summer pruning to correct shape of shrubs and trees. Pruning now will encourage the least unwanted growth.
❑ Watch for destructive insects, and hand-pick or blast off with water, if possible.
❑ If tomatoes get brown papery bottoms or peppers get brown papery sections on the side, it’s usually because of a calcium deficiency caused by uneven watering. As long as temperatures are predominantly under 100 degrees, deeply water in-ground tomatoes once a week. Higher daytime temperatures mean you need to water every four or five days. Container plants need more frequent — even daily or twice-daily — watering in very hot weather.
❑ Harvest shallots and onions when tops die back. Harvest garlic.
❑ Fertilize roses for last time this season. Most gardeners stop fertilizing roses by Aug. 15.
❑ Prune maple and birch trees, removing crossing and weak branches.
❑ Harvest peppers to stimulate further production. Harvest and dry or freeze herbs.
❑ Divide crowded and nonblooming bearded and Siberian iris. If you’re going to divide Oriental poppies, do it during summer dormancy.
❑ Collect, dry and label seeds from nonhybrid plants.
❑ When corn silks turn brown and dry, start checking for ripeness (ear ends inside husks should be rounded instead of pointed).
❑ Plant fast-growing lettuce and Asian vegetables early in the month for harvest before winter.
❑ Plant spinach and mache for early spring crops.
❑ Pot up frost-tender herbs and peppers for wintering indoors.
❑ Divide peonies, if you feel you must. They can grow for many years without being divided.
❑ Feed lawn 1/4 of its annual fertilizer requirement.
❑ Harvest winter squash when a thumbnail won’t penetrate the skin; cantaloupe when it dislodges easily from the vine, when ants appear, or when your cat/dog takes a bite; and watermelon when the belly is yellow and the vine tendril nearest the melon is brown and dry.
❑ Harvest basil if temperatures are predicted to fall below 38 degrees.
❑ Average killing frost is about Oct. 10.
❑ Plant wildflower seeds that need stratification (freezing and thawing).
❑ Later in the month, plant garlic and shallot cloves.
❑ Remove long canes of roses that could damage other canes by wind whipping. Give trees deep drinks of water.
❑ Start cleaning garden. Disconnect hoses. Have sprinkler system blown out in early October.
❑ Dig sweet potatoes.
❑ Spread last half of lawn’s annual fertilizer allotment in two sessions, a week or two apart.
❑ Use power mower to vacuum and shred leaves for use as winter mulch or as additions to compost.
❑ Plant spring flowering bulbs after soil temperature drops below 60 degrees. (Buy your bulbs earlier in the season if you want a better selection. Keepin a cool, dry place or refrigerate.) For winter cheer, buy bulbs for forcing indoors.
❑ Harvest parsnips, kale, collards, brussel sprouts, beets, turnips, leeks and carrots after a moderate frost or light snow. Flavor will be sweeter then.
❑ Check trees and shrubs for weak or broken branches that may be felled by snow later. You can remove these now, sparing your tree or shrub damage that might admit disease.
❑ Once the ground freezes, mulch perennials, taking care not to pull mulch tightly around the main stem or trunk. Leave an inch or two ring open around stem or trunk, lest you create ideal conditions for crown rot.
❑ Rake leaves from flower beds to keep them from matting and directing moisture away from plants.
❑ Cover strawberries with Christmas tree twigs, pine needle straw or other straw not contaminated by herbicides.
❑ Make holiday wreaths or holiday decorations of conifers or other evergreens.
❑ Read catalogs and dream. Order seeds early, taking care not to order if you still have viable seeds from last year.
❑ Check stored vegetables frequently, removing those that have rot or other spoilage indicators.
❑ If you haven’t already, cover compost pile with tarp to prevent rain and snow from leaching nutrients out of the pile.
❑ Plant onion, shallot and leek seeds indoors.
❑ Inventory holdings in freezer and pantry so you can plan what to include and how much to plant in your veggie garden this year.
❑ Inspect garden tools. Remove any rust. Sharpen spades. Get mower sharpened and serviced.
❑ Check the “bones” of your landscaping for visual appeal, and make plans to improve it with added shrubs or hardscaping.
❑ Plant seeds of broccoli, cabbage and other cole crops indoors.
❑ Prune trees/shrubs (except for spring bloomers such as forsythia and lilacs), trees and grapevines.
❑ Late in the month, begin removing winter mulch.