Spring Garden Cleanup Checklist: When to Start and What to Cut

When to Start Spring Garden Clean Up

Spring garden clean up happens in two stages. Jobs that disturb no living thing, such as picking up branches, clearing paths and servicing tools, can start in late winter. Work in the beds waits. University of Illinois Extension advises holding off during March and early April, treats mid-April as the earliest date to consider, and names the ideal as the point when low temperatures are reliably in the 50s°F. That is about when tomatoes go out, usually around mid-May in Illinois.

The reason is insects. Many pollinators and other beneficial insects spend winter in leaf litter and inside dead stems, and they do not all emerge at once. A second Illinois Extension article puts the rule as waiting until temperatures are consistently over 50 degrees overnight. The longer the beds stay as they are, the more of those insects make it out.

On a Midwest calendar that works out as follows. Debris, tools and paths fill February through April. Summer-flowering shrubs and ornamental grasses are cut in March and April. Perennial stems wait through March and are trimmed in April and May. Leaf litter stays through March and April and comes off in May and June. Dates run earlier in warm regions and later in cold ones, so go by night temperatures and plant growth where you live.

The Spring Garden Cleanup Checklist

Work down the list in order. The first five items can be done before the beds are ready.

#	Task	When	Detail
1	Pick up fallen branches and winter debris	Late winter onward	Stack twigs loosely in a back corner
2	Clean and sharpen tools, check hoses	Late winter	Before the first pruning day
3	Test whether soil is dry enough to work	Before any digging	Squeeze a handful. It should crumble
4	Prune summer-flowering shrubs	Late winter or early spring	Panicle and smooth hydrangea, potentilla, Japanese spirea
5	Cut back ornamental grasses	Early spring, April in Iowa	To about 4 to 6 inches
6	Trim perennial stems to stubble	Mid-April at the earliest	Leave 8 to 24 inches standing
7	Pile removed stems and leaves loosely	Same day as cutting	Compost them after mid-May
8	Clear leaves from beds	When night lows hold in the 50s°F	Start with the most visible beds
9	Weed, then mulch	After the soil has warmed	2 to 4 inches by soil type, 6 inches clear of trunks
10	Prune spring-flowering shrubs	Immediately after flowering	Lilac, forsythia

Jobs You Can Do Before the Beds Wake Up

A thaw in late winter is enough for the first group. Collect storm-broken branches, rake gravel back onto paths, empty containers that filled with water, and look over hoses and fittings for splits. Sharpen pruners and loppers now, since the first pruning jobs are close. Our guide on how to sharpen garden pruners covers the method.

Stay out of the beds themselves while the ground is wet. Illinois Extension gives a simple test: pick up a handful of soil and squeeze. If it crumbles easily, it is ready to be dug. If it holds together, it is too wet, and working it will leave concrete-like clods when it dries. Let it dry for a few more days and test again.

What to Cut Back First

Pruning order follows bloom time. Iowa State University Extension says to prune summer-flowering shrubs, such as potentilla and Japanese spirea, in late winter or early spring, because they flower on the current year’s growth. Panicle and smooth hydrangeas belong to the same group. Illinois Extension notes that you can remove as much as one-third to one-half of the total mass of these hydrangeas in late winter or early spring. Our late winter pruning guide covers trees and fruit in the same window.

Spring-flowering shrubs are the opposite case. Lilac and forsythia carry this year’s flower buds on last year’s wood, so the best time to prune them is immediately after flowering. Bigleaf and oakleaf hydrangeas also bloom on old wood and are pruned just after they flower. Pruning any of these from February through April, ahead of bloom, removes the flowers you were waiting for.

Ornamental grasses come next. Illinois Extension says to cut them back to about 4 to 6 inches, and Iowa State times the job for April in Iowa, cutting to within 2 to 4 inches of the ground. Illinois Extension points out that leaving the old foliage in place delays the warming of the plant’s crown and slows new growth, so this is one job not to postpone.

What to Leave Standing for Pollinators

Dead perennial stems are nesting sites. NC State Extension sampled stems from 20 gardens in 10 North Carolina counties and found that stems are not occupied in their first winter, which makes the period between the first fall frost and the last spring frost a safe time to trim them. Bees move in afterward. The study found the most nests in stems collected in spring, when about 70 percent of the gardens had at least one occupied stem.

The practical rule is to trim, not remove. NC State recommends leaving a stubble 12 to 24 inches tall, and Illinois Extension recommends leaving 8 to 24 inches of stalk, which keeps stems of varying diameters for different insects. If a prominent bed has to be tidied early, Illinois suggests cutting dead stems no shorter than 15 inches and leaving them. Leave the stubble in place once it is trimmed. NC State notes that stems cut this winter can hold overwintering bees next year, and Illinois adds that new growth quickly covers the stalks.

Treat what you remove with the same care. Pile cut stems and leaves loosely in an out-of-the-way area, small enough that the material does not compress, and keep it out of the compost for now. After mid-May it can be composted or disposed of. A workable compromise for a front yard is to clean a few highly visible beds, or only the edges of a bed, and leave the center and back for later.

Weeding, Mulch and the Lawn

Once the beds are open, weed while the plants are small. Hold the mulch a little longer than habit suggests. Illinois Extension notes that a delay in mulching benefits ground-nesting bees, which need open soil to emerge, and suggests saving mulch for later in the season.

Depth depends on soil. Around trees and shrubs, Iowa State University Extension recommends a 3 to 4 inch layer of wood chips or shredded bark on well-drained sites and a 2 to 3 inch layer on heavy soils. Keep mulch at least 6 inches away from tree trunks. Mulch piled against bark creates conditions for fungal cankers, root rots and rodents. For timing in beds, see when to mulch garden beds. New vegetable or flower beds are a separate job: Illinois Extension recommends working in a 2 to 4 inch layer of organic matter to break up heavy clay and improve drainage.

On the lawn, the cleanup-season decision is crabgrass. University of Wisconsin Extension says soil has to warm into the upper 50s to low 60s°F for several consecutive days before crabgrass germinates, and that forsythia is a usable signal: wait until the shrubs are past full bloom and dropping petals before applying a preemergence herbicide. Do not seed the same area. Germinating grass seedlings are damaged by most of these products, so Wisconsin recommends waiting until late August or early September to overseed treated lawn.

For the tasks that come before spring cleanup, see how to store garden tools over winter.