Half the plants on my front slope crisped brown by mid July. I had set them in May, and the spring sun cooked the thin new roots before they could reach down for water. I lost about eight of fourteen starts that first summer. The next autumn I planted the same plant on the same slope, and those went into cool, damp soil and barely flinched. By spring they had spread and held.
So the short answer on ground cover planting time is this. Autumn is the best time to plant ground cover, spring comes second, and summer is the hardest stretch of all. Set your plants in fall and they get months of mild weather to root in before any real heat arrives.
Autumn wins because your soil is still warm from summer while the air has cooled off. Warm soil keeps roots growing fast, and the cooler air means your leaves lose far less water each day. Fall rain tends to be steady too, so the ground stays damp on its own. You water less, and your young plants spend those weeks building roots instead of fighting to stay alive. They go dormant through winter with a real root system already in place.
Summer does the opposite to a new planting. The heat bakes the top layer of soil where your fresh roots sit. Dry spells hit at the same time, so your plant burns through water faster than its small root system can pull it up. That gap is what killed my May starts. A plant you set in fall skips that trap and meets its first summer with roots already deep enough to reach moisture. That head start is the whole reason fall pays off.
Spring still works as your backup if you miss the fall window. Get your starts in as early as the soil can be worked, while the weather stays cool and the rain still falls. The catch is the clock. Your spring plants have only a few mild weeks to root before the heat arrives, so they meet their first summer half ready. Water them with care through that first hot stretch and most will pull through, but you carry more of the load than you would with a fall planting.
Early Autumn
The best window. Warm soil and steady rain let roots settle in before the cold.
Spring
A solid backup. Plant early so roots form before summer heat moves in.
Summer
The hardest time. Heat and dry soil stress new plants the most, so avoid it.
Your new plants are not on their own once they go in the ground. Water them for about the first three months until the roots take hold and they can fend for themselves. Check the soil with your finger before each watering so you keep it damp but never soggy. Stay on top of weeds hard during years one and two, since that is when weed pressure is highest and your cover is still too thin to crowd them out. By the end of the third growing season your plants knit together and fill the space, and the work drops off for good.
Spread a thin layer of mulch around your starts right after planting. It holds soil moisture and shades the roots through that fragile first season.
Do the prep work before your autumn window opens. Clear out every weed and root you can find first, because a clean bed gives your starts room and cuts down the fight later. Loosen the soil and mix in compost so the roots push through it with ease. Plant in staggered rows rather than a straight grid, which lets the spreaders close the gaps faster and leaves no bare strips for weeds. Then mulch around each plant to lock in moisture and protect it through that first season. Get the timing and the prep right, and your cover will hold the ground for years.
Read the full article: Best Ground Cover Plants for Any Garden
