April Gardening To-Do List

Do your garden beds need some early spring bloomers? Visit garden centers and nurseries now to see what you can find that’s flowering. Options include breathtaking beauties like bleeding heart (above), primroses, basket-of-gold and candytuft.

Or you might opt for ephemerals, plants that paint spring landscapes with pretty blossoms and disappear with summer’s arrival. Many spring ephemerals are native wildflowers that provide good food sources for pollinators. Options include Virginia bluebells, shooting star, mayapple and trillium.

Spring rains can batter pretty daffodils, even breaking stems so flowers end up in the mulch. To keep this from happening, insert some kind of stake near a daffodil clump to help keep stems upright. Use short ring stakes or shrub and tree prunings that are pliable and can be bent into arches with ends held in place by soil. Pruned stems that work well include fruit trees, such as apple, pear, cherry or fig, and coppiced shrubs, like red or yellow twig dogwood.

If you have just a few dandelions in your lawn, you might try digging them after a rain, when soil is moist and taproots should come up easily. Otherwise, try weed-killing sprays that target weeds, not grass. To enhance the spray’s effectiveness, scuff the weed with your shoe, breaking up the leaves a bit before spraying. This creates more openings for spray to enter and often yields a quicker kill.

Early spring is the time to prune summer-flowering shrubs, ones that bloom after June 1. Southern gardeners did this task in February. Northern gardeners who often experience hard freezes in March should do it now. The list includes butterfly bush, rose of Sharon, blue mist spirea (Caryopteris) and summersweet. Clip stems back by one-third to control height and still keep the shrub looking natural. Place cuts just above a bud to encourage branching.

If you tucked your garlic in for a long winter’s nap using a thick mulch of straw, pine straw or autumn leaves, remove the uppermost layer in spring when you see green shoots poking through. Remove it too early, and you risk exposing new shoots to freezing temperatures. A practical rule of thumb is to wait until overnight temperatures are reliably above freezing. Don’t take away all the mulch. Keep a layer in place to help reduce weeds and water needs.

Cool-season vegetables thrive in spring’s sunny days and chilly nights. As soon as you see transplants for sale, tuck cabbage, Brussels sprouts, kale, kohlrabi and broccoli into the soil — either in the garden or containers. Seedlings jump-start the process, or you can sow seeds. Lettuce, spinach, radish and beets grow quickly from seed. Use bird netting to protect plants from nibbling deer or rabbits. All of these crops tolerate late spring frosts so can go in the ground as early as two weeks before the last average frost.

Feed roses as spring growth is kicking into gear. Top-dress beds with a slow-release fertilizer, scratching it gently into soil, or add a 2- to 3-inch-thick layer of compost. Follow label instructions for whatever plant food you’re using. Typically, a liquid rose fertilizer will instruct applying every two weeks until August. A slow-release fertilizer might require adding to soil every six weeks until August. Some rose fertilizers include a pesticide to help defeat common rose pests like Japanese beetles. Read the label carefully, because these products often harm beneficial insects and pollinators.

After all danger of frost has passed and night temperatures are consistently above 60° F, gradually shift houseplants outdoors for the summer. At first, place them in a protected spot on a porch or beneath a tree — somewhere out of direct sun. This allows them to acclimate to wind, rain and sun. Once plants have been outside for a week or two, move them into the spot where they’ll spend the summer. Take out hardier plants first, saving the most tropical for last. Every plant has different cold tolerance, so you’ll have to research to find out which of your plants is more immune to chill.

In spring, you can find pots of forced bulbs for sale at many different retailers, from gas stations to grocery stores to big box outlets. Buy several and drop them into porch and patio pots for a pretty outdoor display. After the bulbs finish flowering, transplant the bulb (with green leaves) into your garden for future spring color. It might take a few years, but your bulbs will recover from the forcing process and reward you with years of blooms.

Mulch planting beds and vegetable gardens once the soil has warmed in spring. Add a fresh layer that’s 2 to 3 inches thick. Use the 3-inch layer in warmer regions, where organic mulch breaks down faster and soil needs a cozier blanket to help retain moisture. Select an organic material, and you’ll be nourishing — and even building — soil as the mulch decomposes. Good choices include ground bark, pine straw, forest bark fines and a host of other regionally available materials. Check with your local extension office to learn what types of local organic mulches are readily available where you live.

Remove any protective mulch from overwintered perennial herbs like thyme, rosemary, oregano or sage. Snip old stems, cutting them back to shape the plant and encourage new growth. If plants like sage (above) show new growth, cut stems back to a sprout. Save cut herb stems to toss into your fire pit for a little backyard aromatherapy, or better yet, add them to a smoker or grill to infuse herbal smoke into your favorite grilled meat. If you have a problem with critters burrowing beneath decking or sheds, shove sage or rosemary stems into any holes as a deterrent until you can fill them in.

Wait to prune early spring-flowering shrubs like forsythia, star magnolia, Russian almond, witch hazel or flowering quince until after they bloom. Prune within the first month after blossoms fall, or you risk removing next year’s flower buds. The exception is removing dead or damaged stems — it’s OK to clip those before flowering. Visit nurseries in spring to find other early-season bloomers you might want to add to your garden.

Known in northern regions as “robin snows,” late spring snows often show up with heavy, wet snow that blankets lawns and gardens alike. The good news is that late spring snows don’t usually harm spring flowering bulbs. Most can handle heavy wet snow without missing a blooming beat. As snow melts, stems pop back up and continue the show. The time to be concerned is when daytime temperatures linger below 29° F, and even spring sunshine doesn’t coax them up. At that point, some flower buds like tulips, fritillaria and lilies will likely be damaged. Otherwise, if the chill just lasts overnight or for an hour or two in the morning, there’s no need to fret.

Lawn grubs start feeding as soil warms, migrating from their underground winter quarters up into the grass root zone area. This is where they’ll munch through turf roots until they’re ready to molt into beetles. Check with your local garden center or extension office to learn what treatments are effective against grubs at this stage of development. Also get advice on what to do for summer grubs, a life stage that’s easier to treat. If you have spring grubs, you’ll probably have summer ones, too.

Species tulips are smaller versions of the showstopping tall tulips. Flowers are typically smaller, and the plant itself may be ground hugging, but the blooms are gorgeous with several colors on petals, both inside and out. Blossoms typically open and close with the sun. Gardeners plant these tulips because they’re reliably winter hardy, returning to grace the spring garden with color year after year. Look for them for sale from bulb companies under the category “Species tulips.”

Spring is a great time to till a large or new vegetable garden. Wait until the soil isn’t bone dry or too wet (clumping together). If you till when soil is too dry, you risk pulverizing the soil particles, which ruins soil structure. If soil is too wet, tilling can cause it to compact. Choose rototilling if you have a new garden area or need to break up heavy clay soil. It’s also a less labor-intensive way to incorporate amendments like manure or green cover crops into soil.

Before setting up a rain barrel, double-check that the gutters are clean. Rinse any debris from the rain barrel, attach the spigot, and make sure the overflow pipe is clear and directed away from your home’s foundation. Check the filter screen for holes and repair as needed. Remember that if your rain barrel has an opening that mosquitoes can fit through, you need to treat the water with Bti (Bacillus thuringiensis israelensis), often sold as Mosquito Dunks, to prevent mosquito reproduction.

Crop rotation is important in the vegetable garden, and even more so following a year with disease or severe pest problems. The idea with crop rotation is that you don’t grow plants in the same plant family in the same spot year after year. You can easily find information about which plants are related online. One example is the nightshade family, which includes tomato, pepper, potato, tomatillo and eggplant. Another example is the brassica family, which includes cabbage, Brussels sprouts, kale, broccoli and cauliflower.

Service your lawn mower by changing the oil and spark plug and adding fresh fuel. It’s also a good idea to sharpen the mower blade and remove dried grass on guards or mower decks. On chilly spring days, if your pull-start mower is tough to turn over, set the mower in the sun an hour or two before you plan to mow. Cover the engine with a black plastic trash bag. The bag will absorb the sun’s heat, warming up the motor. It should rev easier when it’s time to mow.

Keep taking cuttings of sweet potato vines to use as slips for this year’s crop. Place cuttings in water, where you’ll see roots develop within a day or two. Sweet potatoes need warm weather and soil at 70° F to grow. Don’t set them out until two weeks after the last spring frost. In cooler regions, you might not be planting until June. In Zone 8, mid-April is usually the right time — provided the soil is warm.

Early spring and aphids go together like bagels and cream cheese. These pesky pests thrive in cooler weather. Watch for them on lush new growth of plants, including roses, chives, kale and pansies. Traditional control methods include using a spray of water to knock them off plants or spraying with insecticidal soap or neem oil. It also helps to have a landscape that attracts insect-eating birds, like Carolina wrens, house wrens or chickadees.

Make a plan for your container gardens to create the most efficient shopping. It will save you time and money, and you might end up with your most stunning containers ever. It’s also a good idea to double-check your container garden supplies and clean up pots if you didn’t last year. Don’t forget to scrub pot sides to remove moss and dirt. Replace at least one-third to one-half of the soil in large pots that you don’t completely empty, adding used soil to in-ground beds or the compost pile.

Healthy plant roots are white and with a well-established plant fill the soil volume in a pot. When you’re out plant shopping, you can often slip a plant out of its pot by gently squeezing the pot sides. This shows you if the root system is healthy. You don’t really need to do it on every plant, but if a plant seems small for the pot or has unhealthy-looking leaves, you might want to check the roots.

By the way, this plant is sweet alyssum, traditionally a cool-season annual that provides a great nectar supply for beneficial insects. Plant breeding programs have produced sweet alyssum varieties that flower from early spring until the first fall frost. Try Proven Winners' Snow Princess sweet alyssum for season-long flower power.

Tuck strawberries into a hanging basket for a beautiful, edible container garden. Choose day-neutral or alpine strawberry varieties for containers, since these types expend energy forming fruit and not runners. Day-neutral berries need at least six hours of sunshine (full sun) daily, while alpine types yield fruit in part shade. Alpine berries are smaller, but quite flavorful. Ask your local garden center if they carry any strawberry varieties developed for container use.

Spring is a great time to do a soil test on garden beds. This is an important step with new planting areas, but also with established ones and more so if you haven’t taken a soil test in a while. The test measures things like soil pH and some nutrients, including phosphorus, potassium and calcium. Results include recommendations of what you should add to soil — maybe lime and/or fertilizer.

Mowing grass too short harms grass and gives weeds a chance to grab some sun and grow. Learn what kind of turf you have, and check with your local extension office to learn the proper mowing height. A general rule of thumb is to mow cool-season grasses, including bluegrass, fescue, ryegrass and wheatgrass, to a height of 2 to 3 inches. Warm-season grasses are usually mowed to a height of 1 to 2 inches. This includes bahiagrass, centipede and St. Augustine. Zoysia and bermudagrass are kept shorter (1/2 inch). Time mowing to remove just one-third of the total grass blade length.

Plan for stunning summer color by using tender summer-flowering bulbs to fill in bare spots in the garden. Good candidates include dahlia, calla lily, canna and gladiolus. All of these bulbs come in a host of blossom colors, and dahlias also offer striking flower forms. Canna and also caladium add color through boldly tinted leaves. Insert stakes for tall dahlias at planting time to avoid spearing tubers by adding stakes later. In cold regions, wait to plant until all danger of frost has passed.

If you have lots of trees, invest in a small leaf shredder to transform those leaves into homemade mulch. Native oaks found in the South and West typically drop leaves twice each year, providing great material for mulch or adding to a compost pile. Choose a shredder that can also handle twigs and small branches, and you’ll be able to deal easily with all the tree debris that storms scatter on the lawn.

Wait until all danger of frost has passed to plant warm-season edibles, including summer squash, tomato, pepper and eggplant. Soil needs to be at least 60° F for success with heat-loving crops like corn, cucumber, melon, green beans, zinnia and sunflower. Check average soil temperatures online, or give it the ol’ barefoot test. Soil that’s 60° F is comfortable to walk on barefoot. Typically soil reaches this temperature two weeks after the last average frost date.

Seed packets contain all the information you need to plant successfully. Often the packet includes a small map that shows when to plant in your region. The packet also tells you if you can or should start the seeds early indoors. To know when to plant seeds, look for the packet information about how many days the crop takes to flower or reach maturity. Count backward using that number of days, and that’s when you should be planting those seeds.

Add stakes or flags to clumps of spring bulbs that are crowded and need to be divided. You could also try taking a picture of the clump with its marker as a backup reminder. The best time to dig bulbs for dividing is after leaves die back. At that point, flower buds have already formed inside the bulbs, so you won’t risk aborting next year’s bloom bonanza.

Grab a bucket and start bailing water gardens, removing any dead leaves and other mucky stuff before refilling for the season. Bury the material you remove in the compost pile to help contain the smell. Divide water lilies and other aquatic plants at this time. Start feeding fish when the water temperature hits 50° F. Try to refill your water feature early enough in spring that it’s ready for toads and frogs to use for breeding, and you might be rewarded with a fresh crop of amphibian bug eaters.

Give your houseplants the spa treatment by removing any dead or weak stems and leaves. Repot ones that are super crowded in their pots or that look like this dracaena when you slip it out of its pot. That condition is known as rootbound. Before repotting, loosen roots with your fingers or a sharp pair of pruners. It’s okay to clip away up to one-third of the total root ball. The plant will generate new roots when it’s settled into a slightly larger pot with fresh soil.

If you use a compost tumbler system, you probably have finished compost that’s ready to go. If you maintain a traditional pile and didn’t harvest finished compost last fall or garden in a warmer region, check for finished compost now. Compost makes a great addition to planting beds and vegetable gardens. It’s also a terrific top dressing or surface mulch around roses, clematis and cane berries.

There are two times of year that you can aerate the lawn: spring and fall. When you do it depends on where you live and the type of grass you have. Warm-season grasses are aerated in late spring to early summer. Cool-season grasses are best aerated in fall. Typically, you want to aerate your lawn every two or three years to help reduce compaction and remove thatch. Rent a machine that removes plugs of soil, or hire a lawn service to do it.

Spring means fresh, tender growth, which flashes like a neon sign to slugs. Start your slug control as early as possible in spring, focusing efforts on plants with new shoots. Purposely leave a board lying in the garden to provide a hiding place for slugs. When the sun is out, carry a bucket of soapy water to the garden, lift the board, and scrape the slugs into the suds. Or use slug traps that you station in areas with the most problems. Every slug you eliminate in spring is one less to feast on your garden later — and one less that can reproduce to make more.

When climate chaos threatens to take out young garden plants with an extra-late frost, cover plants with a horticultural frost blanket, an actual blanket or a towel during the critical low-temperature hours. To extend your growing season and set out plants a few weeks early, use a product like a garden cloche or a wall of water protector (above) to create a toasty microclimate for seedlings.

In the desert Southwest, iron deficiency is common in spring, especially on camellia, gardenia and citrus, but it also occurs on many landscape plants due to the high alkaline soils of the region. The symptom to watch for is yellow or yellowing leaves with green veins. The main center vein on a leaf will be easy to spot. Address the problem by applying a chelated iron product. Check with your local extension office to determine which product works best in your soil.

Clearly defined bed edges set off planting beds, giving them a finished, professional look. With the simple investment of some elbow grease, you can dig deep trench edging that’s easy to maintain and mow. Tackle this task in early spring, when soil is moist from rains and air temperatures are cooler for hard work. Don’t fill up your trench with mulch so it's level with turf. It should gently slope down from the plantings to the lawn. You want a clean-cut edge on the grass side so that turf roots are exposed to air and unable to grow into the bed.

Make room for an early spring shrub that scents the air with a spicy perfume. Koreanspice viburnum (Viburnum carlesii) unfurls gorgeous blooms packed with a floral fragrance that’s a just-right antidote to spring fever. This shrub typically forms a tidy, rounded shape and comes in a variety of sizes. There’s something to suit even the smallest garden, or use the full-size version to create a stunning spring hedge. Fall foliage is red, but it’s the early show of floral finery that will have all the neighbors wondering what smells so good. Hardy in Zones 4-8.

If your lawn features naturalized bulbs, such as crocus, snowdrop, scilla or daffodil, don’t start mowing that section until bulb leaves have died back naturally. This means you’ll have a meadow area for a bit, but that longer grass brings benefits. It provides the perfect hang-out for ground beetles, which have a big appetite for pests and weed seeds. Different ground beetle life stages and species eat different things, but some organic farmers actually maintain a long grass area to give these beneficial predators a home.

If your peonies tend to flop and maybe even break under the weight of the flowers, consider adding grow-through plant supports. You can build one easily using bamboo stakes and twine to create a grid for stems to grow through. Or you can purchase powder-coated steel grow-through stakes. Just make sure you’re buying stakes that are sturdy enough to keep the top-heavy stems upright.