This is taken from IdahoStatesman.com. This is for Boise, so if your climate is similar to Boise's this may be helpful to you.
March 15, 2009
When does your garden grow?
Our experts have pulled together this year-long guide on
what to do in your garden
® Begin seeding plants indoors to transplant later.
® Expect roller coaster temperatures. Don't get impatient and plant too early.
® Prune trees and shrubs, except for those, like lilacs and rhododendrons, that bloom on old wood and have already set their blossoms.
® Tend clematis. Remember, they are grouped into three pruning categories. Save the tag when you buy one to know what you have.
® Plant primroses and pansies.
® VEGETABLES: In early March, plant lettuce; spinach; St. Patrick's Day, or as soon as soil can be worked, put in peas; spinach; kale;
leeks, potatoes, onions; late March/early April, it's carrots; beets; endive, chicory, sweet potatoes (sweet potatoes need "extraordinary"
protection; Walls of Water are good).
® Remove winter mulch from beds so the sun can warm the ground.
® Shear back groundcovers.
® Wake up your flower beds with a general fertilizer.
® Prune roses when forsythia blooms. Cut roses back 1/3 of height. Fertilize.
® Divide perennials, except dicentra, pulmonaria and other early bloomers.
® Plant conifers, trees and shrubs.
® Plant summer bulbs: alliums, cannas, convalaria, bare-root hostas and daylilies.
® Last average frost day of the year: April 29-May 9.
® VEGETABLES: Mid-late April: Asian greens, like bok choy
® Tend peonies: "Disbud," or remove side buds for a big central blossom. "Side-dress," or sprinkle the ground around each plant with
one tablespoon of triple super phosphate for thick stems and big flowers.
® Deadhead, or remove, spent blossoms from spring bloomers like tulips, daffodils and crocuses. Don't remove foliage.
® Time to harden off seedlings started indoors.
® Local legend says that when the snow is melted off Shafer Butte north of Boise, it's safe to plant annual flowers.
® If you haven't fed your roses, do it now.
® Stake delphiniums and other tall perennials.
® VEGETABLES: Mid-May: corn; late May: cucumbers; beans, squash, melons
® Pinch back asters and chrysanthemums for fuller plants.
® Keep deadheading roses and other flowers for continued blooms.
® Prune spring-flowering shrubs - lilacs, forsythia, rhododendrons.
® Mulch trees and perennials; leave breathing room around trunks
Stop fertilizing trees by June 15.
® VEGETABLES: Pepper, tomato, eggplant seedlings.
® Water trees deeply. Fewer, deeper watering sessions are better for root development than frequent, light watering.
® Prune wisteria.
® Disbud, or remove side buds on dahlias to promote bigger, central flowers.
® Prune vines if they're sprawling.
® Divide iris.
® Get weeds out of your garden now before they go to seed and make more weeds.
® VEGETABLES: If you do like to start seeds indoors, start kale, collards, broccoli and cabbage to transfer to the garden in September.
® Keep watering - daily for containers and hanging baskets.
® Helenium, heliopsis, rudbeckia (black eyed Susan) all look great in your late summer garden when most other things don't.
® Stop fertilizing roses by Aug. 15 to prepare them for winter slow-down.
® VEGETABLES: Chinese cabbage: start indoors Aug. 1, transplant outside in September or October.
® Watch for sales at local greenhouses with discounts between 30-50 percent.
® Plant peonies, poppies, grasses and other perennials you find on sale.
® Prune Annabel hydrangea, pussywillow, and other bushes that bloom on new wood.
® Clean up flower beds.
® Bring tropicals, cacti, citrus inside for the winter. Inspect them first to make sure they're pest-free.
® Walk through the garden and take an honest look at what plants worked for you, and what plants didn't. Don't get sentimental. "Prune
with a shovel" is the motto of some gardeners.
® Don't add mulch to beds until the ground is frozen. Start cutting back on water.
® Dahlias, cannas, gladiolus are not winter hardy and should be dug, packed in packing peanuts, wood shavings, or newspaper shreds,
and stored in a dark, dry, chilly place until next spring. Geraniums, too.
® Plant bulbs, like tulips and daffodils, for next spring.
® Pull annuals and compost. Don't leave them in the garden to rot and get slimy.
® VEGETABLES: Lettuce, with care. Planted too early in the month, while it's still hot outside, lettuce will "bolt," or go to seed too
® The first killing frost: Oct. 7-16.
® Don't prune roses, but cut tall branches vulnerable to winter wind breakage.
® Rake fallen leaves out of flower beds. They can harbor disease and pests.
® Shred fallen leaves to use as winter mulch. Leaves that aren't shredded can form a mat around your plants and breed disease.
® Apply Wilt Proof to seal moisture in broadleaf evergreens such as holly, laurel, rhododendron, azaleas, hardy camellias, magnolias.
® Spring bulbs such as tulips go on sale and can be planted through December, as long as the ground isn't frozen.
® VEGETABLES: Plant garlic, shallots, lettuce, before ground freezes.
® Cut evergreen branches and twigs to display in pots.
® Get out the hose to water trees, shrubs, and other plants, especially under the eaves of the house, or in other areas where rainwater
can't reach. Remember to unhook the hose from the house when you're done.
® Avoid digging in or walking on moist soil for the next couple months. It's easy to compact soil and damage it.
® Cut back hellebores (Lenten rose); don't cut new blossoms hiding beneath leaves.
® Conifers, red and yellow twig dogwoods are showing winter color.
® Peruse catalogs, but check with your local greenhouse to see if they will carry the plants you want. Support a local business and save
® The month of the "big tease", when that inevitable week of freakishly warm weather fools you into thinking spring is here. It is not.
® Cut back buddleias (butterfly bush) to six inches. Also cut vitex, caryopteris, Annabel hydrangea - all of which bloom on new wood.
® Prune fruit trees.
® Spray dormant oil on woody plants to control aphids and other pests. Follow label directions.
® Roses and trees are dormant. This is the perfect time to move them without shocking them.
® Apply Wilt Proof to seal moisture in broadleaf evergreens
® If you left perennials standing through the winter for food and cover for birds, cut them back now.