By Sharon Morrisey,
Consumer Horticulture Agent
Milwaukee County University of Wisconsin-Extension

May    June   July   August
September   October   November   December

First Week in May

The best way to improve garden soil is by working in organic matter every year. Sandy soils will hold moisture and nutrients better and clay soils will have better drainage and aeration. Use compost, composted manure, leaf mold or peat. If you mulch your garden with straw, it too can be worked in at the end of the season to breakdown over winter.

Cool temperatures and even a frosty night will not harm pansies, snapdragons, petunias, lobelia, alyssum and dusty miller. These are perfect for gardeners in cool climates who are itching to plant something flowering.

Second Week in May

Seeds of several crops can be sown directly into the garden even if the soil is still cool. They include lettuce, spinach, peas, beets, carrots, chard, kohlrabi, mustard, potatoes, radishes and onion sets.

To properly plant trees and shrubs, prepare a hole twice as wide as the existing root ball. Depth is determined by pulling away soil from around the base of the trunk until the root flare is visible. Plant only deep enough for this flare to be visible, being careful not to disturb the soil at the bottom of the hole, which will settle deeper along with the tree after it has been planted for awhile. Backfill with the same soil you removed from the hole without adding other organic matter. Wait until the end of the second year to fertilize newly planted trees and shrubs.

Third Week in May

Several crops can be transplanted as plants into cool soil, including head lettuce, onions and parsley, as well as all of the "cole crops," broccoli, cauliflower, cabbage and Brussels sprouts.

Young transplants can be protected from cutworms by surrounding them with collars made of paper cups, yogurt cups, tin cans, etc. that have both ends cut out. They should not be directly against the stem and can be one to two inches away on all sides.

Plant new perennial flowers and dig, divide and transplant those that flower in mid-summer and early fall. Early spring flowering perennials should be divided in fall. Be sure to set peonies and irises shallowly. Take this opportunity to add organic matter to improve the soil. Apply a two to three inch layer of organic mulch once the soil has warmed.

Fourth Week in May

Vine crops such as cucumbers, zucchini, squash, pumpkins and melons have brittle roots that easily break during transplanting. Start seed or buy transplants in degradable containers such as peat pots that may be planted pot and all directly into the garden. Break off and remove any of the pot sticking up above the soil since this will wick water away from the roots. Pre-warm the soil before planting vine crops, tomatoes and peppers by covering it with black plastic for several sunny days beforehand.

Watch for the obnoxious weed Creeping Charlie to start flowering in lawns and gardens. Pull by hand as frequently as possible to minimize the spread of this vigorous weed. Hand weeding seldom controls it completely. Large infestations may be brought down to manageable levels using a weed killer containing 2,4-D. This herbicide is even more effective when applied after the first light frost in the fall.

Early June

Plant tomatoes lying in a trench burying the roots and stem up to the first set of true leaves. This is the only vegetable crop that will form roots along the buried stem giving the plant a large, extensive root system. Do not fertilize tomatoes until the first fruit has set from the blossom. Nitrogen will prevent fruit set while encouraging vigorous growth of leaves and stems.

In central and northern zones, it is time to fertilize cool season lawns of bluegrass and fescues. However, the most important applications for your lawn are the ones done in the fall while air temperatures are cool and soil is still warm, yet moist. Bluegrass should receive from one to five applications per year.

First Week in June

Cover "cole crops" - broccoli, cauliflower, cabbage and Brussels sprouts - with floating row cover to prevent egg laying by cabbage months, cabbage loopers and diamond back moth. Row cover is a poly spun-bonded fiber that allows sunlight and water through but keeps out insects. Allow extra space for the plants to grow under the row cover. Seal at the ground with boards, bricks or rocks. Any openings will allow insects to sneak inside.

It is finally safe in almost all zones to transplant even the most tender flowers and vegetables outdoors. If night temperatures are cool or the site very windy, "harden-off" plants for a couple of weeks first by setting them outside in a somewhat protected site until ready to plant.

Second Week in June

Once the soil has warmed, apply a layer of organic mulch to all the bare soil in your garden. It will hold in warmth but keep soil from becoming too hot, as well as conserve moisture and reduce weed growth. Use 6 inches of straw or 2 to 4 inches of composted yard waste including decaying leaves.

Third Week in June

Look for small green caterpillars on cole crops such as broccoli, cauliflower and cabbage. Spray with the biological pesticide Bacillus thuringiensis (B.t.) sold as Dipel, Thuricide, and several other brand names. Prevent adult moths from laying eggs on these crops earlier in the season by covering them with floating row cover fabric.

Fourth Week in June

Striped and spotted cucumber beetles are yellow and black and begin feeding on most of the vining crops as soon as their leaves begin to emerge from the soil. The beetles themselves cause little damage but carry and spread bacterial wilt which will eventually kill the plants. Control the beetles by spraying or dusting regularly with the botanical pesticide rotenone or with the synthetic carbaryl (Sevin.)

First Week in July

Vigilantly watch the lower leaves of tomatoes for small brown leafspots of septoria and early blight fungus. Immediately remove spotted leaves to prevent spreading to the rest of the plant. Remove leaves from the garden. Mulch the soil under tomato plants to prevent splashing of spores up from the soil. Rotate the location of tomatoes and all Solanaceous crops in at least a three year cycle. Severe infestations may require a fungicide with chlorothalonil such as Daconil.

Second Week in July

Examine the bases of stems of vining crops for brown egg masses or signs of boring and tunneling of squash vine borer. Remove egg masses by hand. Stems with holes and sawdusty-appearing blobs pushed out of borer holes can be slit upward lengthwise to find the larvae inside the stem and destroy it. Then bury the stem portion with soil. Prevent egg-laying in late June by covering the lower six inches of the stems with floating row cover or other material.

Third Week in July

A late crop or second crop of many garden vegetables can be started in mid-July for harvest in the fall. Transplants of broccoli, cabbage, cauliflower, Chinese cabbage, collards, kale, kohlrabi and onion sets can be planted now.

Fourth Week in July

Allow asparagus spears to grow and form wispy tops now. Fertilize with a balanced fertilizer such as 10-10-10. Keep beds weed free and well watered all summer. Watch for the black and red asparagus beetles.

Third Week in August

Harvest onions and garlic as the tops dry down and fall over. Before storing, once the leaves are completely dry, cut them back to 1 inch. Then cure in a warm dry spot with good air circulation for another week or two. Then store in a cool, dry spot.

Fourth Week in August

Seeds can be sown again for a late crop of leaf lettuce, mustard greens, Swiss chard and spinach.

Pick fall bearing raspberries as soon as they ripen. Overripe fruit left on the plants will attract picnic beetles which will seriously damage fruit that has yet to ripen. These stems will produce another crop early next summer. For ease of maintenance and better disease control cut down all stems to the ground in the fall, if you are willing to sacrifice the early crop next year.

First Week in September

For fully ripe tomatoes, leave the completely red fruits on the plants for another five to eight days during the warm, sunny days of August and early September.

Second Week in September

Watermelons are ripe when the fruits are full size, dull in color and the portion touching the soil turns from greenish white to cream. The tendrils nearest the melon curl and dry up when a melon is ripe.

Third Week in September

Cole crops such as broccoli, cauliflower, cabbage and especially Brussels sprouts become even more flavorful and productive during the cool fall weather. July transplants of these crops should be ready for their first harvest.

Fourth Week in September

Watch nightly weather forecasts for frost predictions. Prepare to protect tomatoes and peppers still trying to ripen. Even if you can protect them from frost, once the days are consistently cool, ripening slows enough that you don't gain much by leaving them on the plants. Harvest full sized ones and ripen indoors in a paper bag or box. Smaller ones can be fried green.

Fall Wrap-up

Plant individual cloves of garlic now for a crop of garlic bulbs next summer. Select very large cloves to produce the largest bulbs. Plant them 6" deep and 6" apart.

Pumpkins, summer squashes and gourds for storage should be harvested before the first frost. Take care not to nick the rind since this will diminish the storage time.

Carrots, leeks and potatoes can tolerate freezing temperatures. Mulch them with straw and leave them in the ground to be harvested as needed well into December.

The frost will soon be on the pumpkins in northern climates, if it isn't already. Prepare for next year's garden by clearing away any diseased plant remains and forking under everything else.

Organic matter added now and even roughly turned under will decay in place, making the soil dry faster and warm sooner next spring.

First Week in November

The "cole crops", broccoli, cauliflower, cabbage and especially Brussels sprouts continue to grow well in cold weather and can be harvested as long as they are producing. Leave a portion of the stem in the ground when harvesting the main "head" of broccoli, cauliflower and cabbage because smaller ones will form just below the point where the first ones were cut off.

Second Week in November

Cut back fall bearing raspberries immediately after harvest. By pruning all canes down completely each fall, next years harvest will be increased and disease and insect pests as well as winter wildlife damage will be minimized.

Third Week in November

The pilgrims were just gardeners giving thanks. Think about the dishes they probably actually had at their feast that are still traditions - squashes of several varieties and wild nuts and berries, some of which may have been cranberries. The Indians probably also taught them to prepare corn dishes including bread, pudding and hominy.

Fourth Week in November

If you grew your garden in containers, they should be brought in for the winter and cleaned. Left outside where they will get wet they will break when the soil freezes and expands. Do not save old soil but replace it. This is how you practice rotation for disease control when container gardening.

First Week in December

Take a sample of your garden soil before it freezes too deeply. Dig several slices with a spade that are 4 - 6" deep from 5 - 10 different sites in the garden. Mix them together and send about 2 cups of it to a local, state certified soil testing lab. Contact your County University Extension office for more information.

Second Week in December

Cut asparagus ferns down to the ground after they have become yellowed by a couple of frosts. This helps prevent infection by rust disease. Now is also the time to control weeds with shallow cultivation.

Third Week in December

Continue harvesting carrots, potatoes, parsnips, rutabagas, celeriac and leeks that were mulched earlier and left in the garden.

Fourth Week in December

Move all garden chemicals and other products to an area where they will not freeze. It should be dry and safely out of the reach of all children.