April Gardening Tips: Prune Grasses, Spread Corn Gluten Meal, Start Dahlias

By Guest Authors Charlie Nardozzi, Horticulturist, and Leonard Perry, University of Vermont Extension Professor.

April is the official start of the home gardening season and there’s much to do!

Prune Ornamental Grasses

If you left your ornamental grasses intact for their fall and winter effect and for seeds for birds, prune them back in April to a height of 6 to 12 inches. If you remove the old growth before new growth starts and don’t cut back too close to the ground, you won’t damage new sprouts when they emerge later in spring. Add prunings to the compost pile, but the thick stems of some grasses should be shredded or cut up first so they’ll decompose more quickly.

Prepare Patio Containers

When preparing large containers for the deck or patio, save on soil by creating a false bottom. Most container plants don’t need more than 12 inches of soil depth for their roots, so add a few empty plastic soda or water bottles in the bottom, then cover with a piece of cardboard cut to fit the shape of the container. Plastic pots turned upside down also work, as do coarse wood shavings. Styrofoam packing “peanuts” also work well – put them in plastic bags so they’re easily handled and contained.

Spread Corn Gluten Meal On Your Lawn

To control annual weeds in the lawn, spread corn gluten meal with your lawn spreader when forsythia are blooming. That’s when many weed seeds like crabgrass are germinating. It’s a safe, organic option for preventing the germination of weeds, and it provides a small dose (maybe 9 percent) of nitrogen fertilizer. The best controls for weeds, however, remain a good soil conducive to growing grass and proper lawn culture. Like all “pre-emergent” weed killers, corn gluten will keep all seeds from germinating. So make sure any desirable flowers or vegetables have germinated and have “true” leaves (second set) before applying corn gluten meal around them.

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Start Dahlias Now

Get flowers sooner on dahlias by potting up tubers and growing them indoors until it’s warm enough to plant them outside. Pinch the growing tips when they get 6 inches tall to keep the growth short and stocky for easier transplanting into the garden. Keep them in a cool place, such as a garage, so they don’t grow too fast.

Start Leafy Green Vegetables

To get a head-start on fresh leafy salad greens, sow seeds in a large, shallow container. Keep the container outside during the day and bring it in at night if the temperatures dip below freezing, or protect it in a cold frame. A window box with colorful greens is not only ornamental but makes for easy picking and protection from hungry rabbits.

Cut Back Butterfly Bush, Sage, Rue, and Artemisias

Woody perennials differ in the way they should be cut back in spring. If butterfly bush has died back, cut the dead stems to the ground, otherwise just shorten them by about one third. Cut back Russian sage, rue, and artemisias to about 8 to 12 inches from the ground. Don’t prune lavender until new growth appears, and then just shorten the stems by about one-third. Heather should be lightly pruned to remove the old flowers and the tips of the shoots, but don’t cut back to brown wood, stay in the green. Wait to prune roses until shoots and leaves emerge, in order to know what stems are dead wood and which are living.

About the guest authors: Charlie Nardozzi is a nationally known horticulturist, author, gardening consultant, and garden coach. Dr. Leonard Perry is an Extension Professor at the University Of Vermont and an advisor to the Vermont Association Of Professional Horticulturists. This article originally appeared on Perrys Perennials.