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Wednesday, May 15, 2013

Guilt-free Gardening: Grow a ‘Wetland in a Pot’

California Rush (Juncus patens), Basket Rush (Juncus textilis), Marsh Baccharis (Baccharis douglasii) and Yerba Mansa
 (Anemopsis californica) in a large container wetland

It may seem inappropriate to even consider wetland plants when Southern California is experiencing one of the driest seasons on record.   But in a hot, dry summer, the lure of lush wetland plants is almost irresistible.   If you like the idea of native wetland plants – but don’t have the room or water to spare for a rain garden (see March 2013) - consider planting a ‘wetland in a pot’.  You can create a mini-marsh or attractive wetland container that satisfies your craving for green without feeling guilty about wasting water.

The first consideration is where to locate your container.   Most wetland plants need sunlight for at least 3-4 hours a day; so you can locate your wetland container in a sunny part of the garden.   If you’re fortunate, you may be able to find a location that gets enough sun and is also near a shady seating area; for example, on the  edge of a covered patio.   There’s nothing like admiring your summer ‘wetland’ from the comfort of a shady chair. 
Another consideration is hose or drip irrigation access.  You’ll be watering your ‘wetland’ at least weekly during summer, so be sure you’ve got easy access to water.  If you choose a large pot, your container garden will be heavy.  Better to locate it correctly before it gets filled with damp potting soil and plants rather than after!

Creating a wetland in a container (pot) is fairly easy.  First you’ll need a pot or other container to hold your ‘wetland’.   We suggest a container at least 2 ft. by 2 ft. and at least 1 foot deep.  You can use a smaller size if you plant just a single plant (for example, a single rush (Juncus) plant).  But remember that larger containers – and those made of impervious materials - remain moist longer than do small containers.

The best choice is a container made of thick plastic, composite or glazed pottery. Another popular choice is a wooden half-barrel (whisky barrel) with a plastic liner.  Even a concrete container will work.  Many attractive choices are available - some for reasonable prices.  Choose a pot that complements your home and garden – after all, you’re going to be admiring it a lot.  If you have a choice, stay away from black or other dark colors, as these pots heat up too much in summer.   

Many large pots now come with a removable plug in the bottom hole.   For most situations, it’s best to remove the plug.  With wetland gardens, the choice is up to you.  If you leave it in, you won’t have to water as often – but you’ll need to let the wetland dry out a bit more between waterings.  If you choose wetland plants that require ‘well-drained soils’ then you should definitely remove the plug.   You may want to choose a pot with a threaded plug (like a screwcap) that can be screwed in from either the inside or outside of the pot.  Install it on the outside and you can remove it easily if your wetland garden needs better drainage.

Late spring or summer is the best time to plant a ‘wetland in a pot’. Most wetland plants are not terribly picky about the choice of potting soil as long as it doesn’t have too high a manure content. We suggest using a commercial potting soil rather than soil from your garden.   You’ll want to fill/plant your container in place, as it will be heavy and awkward to move once filled.  Wet down the potting soil and let it settle before planting your plants.  Leave at least 2 inches between the moistened soil and the top of the container (so you can flood the container occasionally).

Many California wetland perennial plants are suitable for growing in containers.  The easiest are the rushes (Juncus species).  These mostly evergreen, grass-like plants have nice shapes/colors and interesting flowers.  They look good alone or combined with other wetland plants.  Some require quite moist soils while others are a bit more drought tolerant.   If you combine several plants in a ‘wetland’ be sure that all have similar moisture requirements.
Basket Rush (Juncus textilis), Iris-leaf Rush (Juncus xiphioides)
and Marsh Baccharis (Baccharis douglasii) in an attractive 
composite pot

Several other wetland perennials are appropriate for a ‘wetland in a pot’.  These include the Narrow-leaf Cattail, the Scouring Rushes (Equisetum species) as well as several more conventional wetland perennials (see below). When choosing plants, be sure to note their mature size.  Some wetland plants are low-growing, while others (like cattails) grow to 4-5 feet tall or more.   The taller species survive just fine in containers; but you don’t want to be surprised when a Cattail or Tule grows to its full height of 6-8 ft. or more.

Many wetland plants look beautiful all by themselves. In fact, some of the most elegant ‘wetland pots’ we’ve seen contain just a single species of Juncus or Equisetum. But if you want to include several plants in your ‘wetland’ then go ahead.  Many nice combinations of plants are possible.  For example, you might combine several rushes with different colors/flower characteristics.  Another possibility would be to pair a rush with several of the more conventional perennial species like Willow Dock and Showy Milkweed. The only trick is to combine plants with the same water and other cultural requirements.
We suggest using no more than three different plants for most home ‘wetlands in a pot’.  If you have a very large container (at least 6 square feet) you can get away with more.  Consider height, flower and foliage characteristics when choosing an attractive combination.  For example, pair an upright species with one that sprawls and covers the soil.  The resources below provide more information about the individual plant species best suited for ‘wetland pots’.

Wetland plants are often ‘spreaders’; plants that increase their size by short underground stems (rhizomes).  This allows them to take advantage of optimal (wet) conditions.   You can count on the plants in your ‘wetland’ to increase in size – sometimes rapidly.  This means you’ll need to do a bit of repotting each year to keep the plants happy.  Some rushes are slow growing, only requiring repotting every other year if grown alone.  Other wetland plants need thinning twice a year in our climate; once in spring and a second time in late summer. 

Fortunately, most wetland plants are incredibly robust.  You can dig the entire plant out of the ‘wetland’, break it apart with your hands (or cut with a stout knife or cleaver) and repot the ‘extra’ pieces into recycled pots.   Just be sure there are 4-6 new stems/sprouts per piece.  The extra plants make nice gifts; be sure to label them so that the recipient knows what s/he is getting.  Replant one piece and you’ll have a rejuvenated wetland.  Add a little fresh potting soil and that’s about it.    

Wetland plants like moist soil.  You can use drip irrigation or simply water with a hose when needed.  Dig down into the soil to assess its wetness.  If the soil is dry at a depth of 2 inches it’s time to water.  Remember that pots dry out surprisingly quickly in hot, windy weather.    Water until the soil is fairly moist but not muddy.  If the soil develops a sour odor – or if the plants become yellow – let the soil dry out to a depth of 6 inches before watering and consider removing the drain plug (if applicable).

Native wetland plants, like most local native plants, like to dry out a bit in the fall.  Gradually water less frequently (let the soil dry out more) beginning in early September.  Once the rains begin in November you can normally leave the watering to Mother Nature.

That’s really all there is to creating and maintaining a ‘wetland in a pot’.   With a little care, wetland pots can give you greenery, flowers, interesting foliage – even butterflies -  for many years. 



You can find a list of recommended plants for a Wetland in a Pot at: http://www.slideshare.net/cvadheim/california-native-plants-for-wetland-in-a-pot-513     Pictures and gardening information sheets for many of the plants are available at: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html
If you missed our yearly (May) sale of wetland plants you can still obtain plants through the Project SOUND nursery at CSU Dominguez Hills.  For availability see:  http://nativeplantscsudh.blogspot.com/p/plants-currently-available.html

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