Year-Round Garden Tips for Northern Climates

Wondering what you could be doing in your northern garden to help it flourish? Check here for tips each month with Northeast gardening expert, Charlie Nardozzi.

Contributors: Charlie Nardozzi of gardeningwithcharlie.com

January February March April May June July August September October November December

Plants mulched for winter.

North Region Tips: January

Designing a New Garden - January is the perfect time to design a new garden. First, map out the hardscape elements like stone walls, walkways and structures in your existing space. Then, start a list of the types of plants you'd like to grow in your new garden. This guide will help you choose the right varieties for your setting.
Houseplant Shower - Light levels are still low in January, so houseplants may not need much attention during this time of slow growth. However, one task I do every month is to give foliage houseplants a shower. Doing so cleans the leaves, increases the humidity around the plant, and makes for a happier houseplant.
Check On Stored Bulbs - If you stored away canna lily and dahlia tubers last fall, now is a good time to check on them. The tubers should feel firm, not wrinkled or soft. If they are too dry, mist them lightly with water. If any are soft and rotting, discard them so they won’t affect the others.
Seed Testing - Now is a good time to do a germination test for the older seed packets you have stored away. To do so, place 10 seeds in a clear plastic bag with a slightly moistened paper towel. Set them in a warm room out of direct sunlight. Check the seeds after one week. If the germination rate is lower than 80%, consider buying fresh seed.

North Region Garden Tips: February

Prune Grape Vines- If you're growing grapes on a wire trellis, remove all but 4 canes. Cut one cane back on either side of the trunk to 7 to 10 buds and the other canes to 3 buds. Attach the longer canes to the wire and remove all other canes on the plant.
Water Evergreens- In warmer parts of our region, as the ground thaws during a warm spell, water your evergreen shrubs such as rhododendrons and boxwoods, to prevent winter burn on the leaves.
Hellebores- Hellebores are one of the earliest blooming perennial flowers. Clean up your hellebore patch, removing dead leaves to allow the new flowers to shine. In warmer areas you can plant hellebores towards the end of the month
Force Branches into Bloom- For a taste of spring, prune off mature branches with flower buds of early flowering shrubs, such as forsythia and flowering quince. Place the branches in a vase of warm water in a sunny spot indoors and the flower buds should open within a few weeks.

North Region Tips: March

Prune Blueberries - Blueberries generally don't need much pruning until they're 5 to 7 years old. Then remove old, grey barked, branches that have few flower buds and encourage newer, smooth barked red or yellow colored branches to form. The goal is to have 5 to 7 healthy, productive branches.
Spray Horticultural Oil – Kill overwintering insect eggs and larvae on your deciduous ornamental and fruit trees, by spraying horticultural oil. Spray on the trunk and branches when the air temperature is above 40 degrees F on a calm day. The oil will smother the insects.
Flush Road Salts from the Soil – When it has been a snowy winter, road salts tend to accumulate in the soil near walkways and roads, and that can kill your plants' roots. For shrubs growing close to the road, flush the road salts by watering deeply once the ground thaws.
Dethatch the Lawn – Once the lawn is dry enough to walk on, rake off the thatch (dead grass) to prevent snow mold fungal disease and allow more air and water to reach the grass roots.

North Region Tips: April

Protect Bulbs - Protect spring flowering bulbs, such as tulips and hyacinths, from deer and rabbits by spraying repellents such as Plantskydd^{^®}. Repeat spraying every few days to protect new growth.
Prune Some Hydrangeas – Prune hydrangea shrubs that bloom on the new wood, such as Hydrangea arborescens and Hydrangea paniculata, now. Both types can be pruned back by one-third. Learn more about pruning hydrangeas.
Build New Flower Beds – Build new raised flower beds using the lasagna method. Layer organic materials, such as chopped hay, chopped leaves and grass clippings topping it with 6 inches of compost. As the materials breakdown they prevent weed growth and feed your plants.
Plant Peas – Plant garden peas and sweet peas once the soil dries. Soak the seeds in warm water overnight before planting. This quickens the seed germination in the soil.

North Region Tips: May

Divide Perennials – Now is a good time to divide late summer and fall blooming perennials such as aster and sedum. They will recover quickly and still flower this year.
Wait to Plant Heat-Loving Annuals – Heat-loving annual flowers such as portulaca, lantana, verbena and sweet potato vines love warm soil and air, so it's a good idea to wait until later in the month to plant these flowers outside.
Plant Strawberries as a Groundcover- Strawberries are great fruiting plants to grow in the garden but also they can make effective groundcovers. Consider planting strawberries around the base of shrubs, small trees and large perennials. Let them spread to cover the ground to help keep it moist and cut down on weeds. You'll even get some berries to boot!
Clean Pots- Clean plastic and clay pots with a 10% bleach solution before planting in them this season. This will remove fertilizer residues and any disease spores in the pots.

North Region Tips: June

Plant Summer Bulbs – Once the soil has warmed, plant summer flowering bulbs such as canna lilies, caladiums and dahlias. These bulbs need warm soil and good air flow to grow well, so planting later in the month is fine. They are heat tolerant plants.
Pinch Flowering Annuals – As trailing annual flowers such as calibrochoa, petunia and scaevola, start to grow, pinch the growth points at the end of the stems. This will result in fuller plants with more flowers.
Deadhead Roses- June is rose month in the North. After flowering, deadhead everblooming and repeat blooming rose varieties to encourage new growth and more flowers.
Prune Shrubs- Prune spring flowering shrubs, such as lilacs, forsythia and weigela, after flowering to reduce their size and promotefuller growth. You have about a 4 week window to prune before these shrubs form flower buds for next year.

North Region Tips: July

Control Japanese Beetles – The adult Japanese beetles are out feeding on your favorite flowers, herbs and vegetables. Hand pick adults in the morning when they're sluggish. Apply the organic spray Bt to kill adults; spray parasitic nematodes or apply milky spore on lawns in late summer to kill the grubs.
Fertilize Container Flowers – The continuous release fertilizer you mixed into your containers when you planted in the spring will be wearing off by July. Topdress your containers with more of it now to keep the plants blooming strong through the fall.
Water Deeply- When watering trees and shrubs in summer, it's important to water deeply but to let the soil dry down a bit before you water again. This encourages the roots to grow deep into the soil so they can better withstand summer droughts.
Keep Planting Annual Flowers- July is a great time to scour garden centers for annual flower sales. Select healthy plants with strong root systems and don't be afraid to cut them back to encourage new, more vigorous growth.

North Region Tips: August

Deadhead Perennial Flowers – Many perennials such as salvia, bee balm and penstemon will flower again in late summer if you deadhead the spent blooms. Once most of the flowers have past, clip out the flower stalks to stimulate new ones to form.
Control Tomato Hornworms – Tomatoes are the most popular garden vegetable and one of their main pests is the tomato hornworm. This large, green caterpillar often has a horn and can defoliate a tomato branch overnight. Look for damage on the top of the plant. Hand pick the hornworms off or spray Bt for larger infestations.
Pick, Pick, Pick- Vegetables are maturing fast and furious in August. Keep picking, especially beans, squash, peppers and cucumbers. The more you pick, the more fruit the plants will produce.
Cut Flowers for Bouquets- Enjoy your flower gardens outdoors and indoors by cutting flowers for bouquets. Cut the flowers just as they are opening to extend their life in the bouquet. Perennial and annual flowers make great cut flowers, but even shrubs like hydrangeas, lilacs and roses make beautiful cut flowers.

North Region Tips: September

Divide Peonies – September is a great time to divide peony plants. Do so by digging up the whole clump, then dividing the plant into smaller pieces with 3 to 5 eyes in each division. Replant the pieces in a sunny location, preferably in well-drained soil. Don't plant the crown deeper than 2 inches in the soil or the peony will struggle to flower.
Plant Trees and Shrubs – Fall is an excellent time to plant trees and shrubs in the North. The shorter days, cool air and relatively warm soil are conducive to strong root growth. Deciduous trees will continue to grow even after dropping their leaves in the fall until the soil temperatures reach about 40 degrees F.
Protect Tender Herbs and Veggies- This time of year in the North, there is always a possibility of frost. Protect tender herbs and vegetables with floating row covers. Protecting your plants from a cool snap in the 30s can mean more weeks of production if the weather warms up again before winter arrives.
Resist Cleaning the Flower Garden- Current recommendations for perennial and annual flower gardens is to leave the flowers in fall and clean up the garden in spring. The mature flower heads provide seeds for birds and the plants provide winter shelter for pollinators.

North Region Tips: October

Fun with Pumpkins – October is pumpkin month with the big splash being Halloween. A fun way to decorate pumpkins is to create a Jack-O'-Plantern. Do so by cutting off the top of your pumpkin and cleaning out the insides. Fill with potting soil and plant it up with small flowers and herbs such as creeping sedum, thyme and pansies.
Leave the Leaves- As the deciduous tree leaves drop, the temptation is to rake and remove them, but leaves are actually good for your yard. Mow and leave them on the lawn as a natural fertilizer. Collect some shredded leaves to mulch around perennials. Make a leaf mold pile for future compost.
Rose Hips- Many roses grow beautiful hips this time of year. Enjoy their beauty and harvest a few to make tea or jam, but leave most of the hips to stimulate the shrub to go into dormancy for winter.
The Last Tomatoes- Before frost occurs, harvest your remaining blemish-free tomatoes as long as they're showing color. To finish ripening, wash the fruits, let them dry, wrap them in newspaper, and store them in a warm room. Check them often, as they won't all turn red at the same rate.

Northern Region Tips: November

Digging Dahlias- Some types of dahlias, like those grown from Proven Winners bulbs, form tubers that can be saved from year to year. However, not all dahlias form tubers as is the case with Virtuoso^® dahlias. When it’s time to empty your pots and take the dahlias out of your beds after they’ve been nipped by frost, dig up the clump and inspect the roots. If there are plump tubers there, they can be saved for next year. If not, send them off to the compost pile.

After digging up your dahlia plants that form tubers, cut the stems back, leaving short stubs. Clean off most of the soil, label the variety and let the tubers dry in a warm spot for about one week. Then, store them in perforated plastic bags or cardboard boxes filled with moistened peat moss, sawdust or wood chips in a cool, dark location for the winter.
Making New Beds- Fall is a great time to build a new perennial flower bed for spring planting. Using the No-Dig method, layer newspaper, chopped leaves, hay or straw, grass clippings and even food scraps like a lasagna onto a bed. Cover with a 3- to 4-inch thick layer of compost. In the spring, just plant right into the bed.
Watering- Even if you have been getting some rain this fall, it's good to keep newly planted perennials, trees and shrubs deeply watered a few times a week. The plants’ roots will keep growing until the soil temperatures reach about 40 degrees F.
Bringing in the Herbs- Don't forget about your perennial herbs growing outdoors. Bring in pots of oregano, parsley, thyme and mint to overwinter indoors. Repot the plants with fresh potting soil, clean up the pot, and place in a sunny window away from cold drafts.

North Region Tips: December

Protecting Evergreens - The best way to protect tender evergreens in winter is to build a burlap shelter. Pound wooden stakes around the plant and wrap burlap around the stakes, attaching them with nails or staples. This will reduce the wind that dries out needles and leaves.
Protecting Hydrangeas - Many northern gardeners complain their bigleaf hydrangeas (Hydrangea macrophylla) don't bloom well or only bloom late. The reason could be the stems and buds died in winter. Protect them by piling wood chips, one foot deep, on top of the shrubs now. This will protect those stems and flower buds so there is less risk of damage.
Gathering Swag - While wreaths are a traditional holiday decoration, I like gathering wild greens to make a swag. Swags are simpler to make and versatile. Gather evergreen boughs of spruce and cypress, mix in some pinecones, colorful shrub stems and berries and hang the swag on your door, wall or even lay it on the holiday table.
Preventing Frost Heaving - Newly planted perennials should be protected from frost heaving by mulching with bark mulch or wood chips. Heaving can happen when the ground freezes and thaws repeatedly in winter. This pushes the new plant's roots out of the ground, exposing them to drying winds.

ABOUT CHARLIE NARDOZZI
Charlie Nardozzi is a Regional Emmy^® award winning, nationally recognized garden writer, speaker, radio, and television personality. He has worked for more than 30 years bringing expert gardening information to home gardeners through radio, television, talks, tours, on-line, and the printed page. Charlie delights in making gardening information simple, easy, fun and accessible to everyone.