Q: I'm getting conflicting information about how to water some new plants that a landscaper installed for us in September (miscanthus grass, 'Knock Out' roses, liriope, kale and pansies).
The landscaper told us to water each plant for a few seconds, and when I was done, to go back and water them again. The grasses dried out badly and died, and the 'Knock Outs,' which were planted in their pots, have not done well either.
We planted new replacement grasses from a nursery, and the people there told us to give them each a gallon of water 2 times a week. Today I bought five new 'Knock Out' roses, and that nursery (a different one) told us the grasses need to be watered 2 times a week for 10-15 minutes on a low trickle whenever it doesn't rain. They also said to remove the pots when planting the roses and water each one on a low trickle for 15-30 minutes twice a week.
Once they are established, I was told to water each grass and rose for two minutes 2 times a week if there is no rain.
Is this the appropriate way to take care of these plants? How many weeks until the grasses and roses become established? I have just been watering the pansies, liriope and kale for 15-30 seconds each twice a week. I appreciate your feedback as my husband and I are complete novices at this.
A: No wonder people get confused. The truth is that there is no one rule of thumb on watering. There are way too many variable, such as:
1.) Plant size. Your little pansies won't need as much water as a tree or shrub, for example.
2.) The weather. Plants and the soil lose more moisture on hot, sunny and windy days than cool, cloudy days.
3.) Soil type. If you've got sandy soil, you'll probably need to water more often than in clay soil.
4.) How much water comes out of your hose. Thirty seconds of water from your hose might be a lot different than 30 seconds of water from my hose. And my estimation of a "trickle" might be different than yours.
But since gardeners need some kind of idea on how and how much to water, plant sellers try to be helpful by coming up with the kind of specifics you heard.
Here's the simple way I look at it. A new plant needs enough water so that the soil around and below its root ball is consistently damp at all times. Moist soil not only keeps the plant alive, it will encourage the young plant roots to venture out into the surrounding soil until it's "established" (another confusing term that I'll get to in a minute).
How do you tell when enough is enough? I think the simplest way is to just stick your finger into the soil beside the plant and see how damp it is.
If it's dry, it's time to water. If it's wet, it's not.
You can also use a stick or similar probe to see how damp the surrounding soil is. And if you really want to get technical, garden centers sell watering gauges that tell you whether it's time to water or not.
The various watering guides you've heard (and there are many others) are just that -- guides. The one your landscaper told you was obviously not enough for the bigger plants. A few seconds of water might be enough to dampen the surface and keep pansies and kale alive, but it's not enough to wet the soil down into the root zone of the grasses and roses.
For that, you need to apply more water over a longer period of time. The garden centers are using the term "trickle" to get you to apply the water slowly enough that it soaks in and doesn't run off. The bigger and deeper the root ball, the longer you're going to have to "trickle" to get enough water to migrate down to the bottom of the rootball and all around it. That's also why most guides advise you to move your hose around during the trickling time to apply the water evenly.
Your roses definitely should've been removed from the pot before planting. Improving the soil with compost and/or peat moss is usually helpful (about 10 percent of the volume is fine), and 2 inches of mulch on top is also good.
Keep the soil around new plants consistently damp until the ground freezes in late fall. You don't want your plants going into winter bone-dry. That's especially harmful to evergreens.
As for when a plant is "established," there's no sudden point where a plant goes from "not established" to "established." It's a gradual process in which a plant becomes more and more able to fend for itself as its roots expand and the plant adapts to its surroundings.
The first six weeks are the most critical. After all, the plant roots are only the size of the pot at first.
Smaller plants, such as your liriope, can settle in pretty well in a year or two. Shrubs can take more like 2 to 4 years to "establish." And trees might not be considered "established" until 4 or 5 years down the road.
What that means for gardeners is that you have to pay more attention to supplemental watering in those early times, then gradually taper back as the time goes along.
Even that doesn't mean you're off the hook once you hit the so-called "established" point. Some plants are naturally more drought-tough than others, meaning some will always need watering help when the weather gets dry while others can go through a whole drought season with no water.
I wish I could give you a quicker and simpler answer, but the best I can do is give you the finger. That didn't come out right. You know what I mean...