The Gardener's April Calendar

As it begins to grow, rhubarb will benefit from a top-dressing of well-aged manure.

The growing season is officially underway, with snapdragon, pepper, tomato and other seedlings growing under the grow lights. Outside, the first of the winter-sown perennial seedlings are emerging in the plastic containers. And the spring bulbs are beginning to put on their show.

Here are some tasks to prioritize this month.

Cleanup and Maintenance:

Give birdbaths a good scrubbing. (I use steel wool pads to do the job.)
I've started to cut back last year's perennial plants because we had a series of days where the air temp stayed above 50 degree F. I lay the cut stems on top of the compost pile to give native bees and insects a chance to wake up and leave (in case they haven't already done so).
If your soil is still wet, hold off on walking on it to prevent it from compacting.
You can create new paths (and even garden beds) by layering cardboard on top of grass and then covering it with mulch.
Remove old foliage from irises to lessen the chance of the iris borers settling in this season.
It's time to sweep up fallen black oil sunflower seeds underneath bird feeders. (The seed will inhibit the growth of other plants.)
Cut back the ornamental grasses. If you don't have a sickle, you can use a serrated bread knife to do the job.
Make sure to repair fencing and trellises that might have endured winter damage. It's a lot easier when the garden hasn't filled in yet for the summer.

To encourage healthy growth on roses, trim out old, diseased or damaged canes.

Pruning:

Paniculata hydrangeas: Here's an early spring task. For more mature plants, you can take a third of the plant off to increase branches in the growing season. Make sure the cuts are uniform so that the entire plant grows at the same rate.
Montauk daisies: Cut them back to encourage new growth.
Roses: As soon as the buds begin to swell on the roses, trim them. (I've also heard it's safe to prune with the forsythia blooms.) I trim out old, diseased or damaged canes and try to remove canes that will impede air flow.
Hellebores: If you haven't removed last year's growth, now is the time. Plus, it makes for prettier photos when you remove all of the older leaves from the last growing season.
Raspberries: Cut back stems that bore fruit last year and anything thinner than a pencil. For the remaining canes, cut back at least 12 inches. If you plan to move your raspberries, now is the time.

Peas grow best in cool weather.

Seeds, bulbs and tubers:

Sow peas! Soak them in water overnight (no more than eight hours) to help germination before planting. Use a soil thermometer to take the temperature of the soil — peas like a soil temp of 45 degrees F and above. The time window for getting peas in the ground is narrow because they stop producing when the temperature gets too warm. If you think you've waited too long to sow the seeds, see if your garden center has plants already growing that you can pop into the ground.
Cool weather crops: Now is the time to get broccoli seedlings outside. You can start planting seeds for lettuce, radish, turnip, beet, arugula, spinach, carrots, collards and kale, too. Start a new crop every three weeks for succession sowing.
Hot weather veggies: Make sure you have sowed your tomato, eggplant and pepper seeds. I try not to start them too soon or they get leggy. Leave a 3 inch gap between plants and the grow lights so they don't stretch too far. (Why not sow some dwarf and micro varieties this year?)
Dahlias and begonias: Pot up tuberous begonias and dahlias now for a jump on the blooming season. For dahlias, look for tubers that have an eye showing.
Last call for bread seed poppy seeds: Scatter the seeds on top of cold soil now so they germinate.

Fertilizer:

Scatter bulb fertilizer around emerging bulbs.
Top dress roses and other perennials with compost.
Top dress rhubarb with well-rotted manure.

Soil test:

Now's the time to send out samples so you can address any last minute issues before the season fully kicks off.

Don't forget to take photos of your garden as the bulbs emerge this spring. They will come in handy in the fall when you are trying to remember how many daffodils you have or where there are empty spots that might need filling in with — you guessed it — more spring bulbs!

What garden chores are you hoping to accomplish this month? Let me know in the comment section below.

I live in Central Connecticut and garden in USDA Zone 6b (average cold weather minimum temperature for my growing region is -5 to 0 degrees Fahrenheit (-20.6 to -17.8 degrees Celsius).

Originally published April 4, 2021. Updated April 17, 2024.