(Gall on a Rosa Woodsii (Woods’ rose), made by a cynipid wasp that has evolved to use roses and oaks as host plants Photo courtesy of High Desert Horticultural Center & WinterCreek Nursery)
Spring is in the air! Well, maybe not today (snowing again), but soon it’ll be gardening season. YEA! So we thought we’d make some recommendations for getting your native plant landscapes off to a good start for the season. There are a lot of things to consider.
The most important consideration in planning spring chores is the kind of work done last fall. Were plants left to drop seed; were plants clipped or sheared; were leaves and needles raked up and removed or were they left over the winter; was compost or other mulch spread over the landscape? But just as important is the question of objectivity. Is the intent of the landscape to create a habitat for animals, pollinators, and other life? Or is the objective to increase efficiency? For example, reduce water use or eliminate fertilizer and pesticide use? Answers to these questions will, to some extent, affect how to approach early season gardening.
All that aside, there are a few basics that apply in just about any situation:
1) Remove most of the leaves and debris that built up over the winter.
There is a lot of information and several opinions on the importance of leaving leaves and garden debris in place over the winter. This material can act as an effective mulch that protects the crown of the plant (where the roots and stems come together) from winter damage, provide overwintering habitat for native insects and beetles, and provide a carbon source for support of essential soil biota through the seasons. But leaving a thick mat of old leaves and garden debris can also suppress plant growth through limiting sunlight and otherwise smothering low-growing plants.
Removing most of the debris in the early spring will allow the soil to absorb heat more efficiently and increase early season growth by opening up the plants to increased sunlight. Don’t remove ALL the debris — leave a light covering to maintain habitat quality and as a carbon source. Remember that one of the benefits of a native plant landscape is a reduction in inputs, including fertilizers. A thin layer of mulch supports fungal and bacterial communities that are responsible for nutrient cycling in the garden, limiting or eliminating the need to add supplemental nutrients.
2) Prune out any dead, dying, or diseased plant parts.
Once plants start coming out of dormancy, it’s generally easy to tell which parts (if any) didn’t make it through the winter. We saw some very heavy wet snow this year, and many plants around the nursery were damaged by the weight. Pruning those out helps maintain the health and structure of the plant and reduces the likelihood of disease or pests moving in.
Be sure to use good sharp pruning equipment. Professional grade pruners such as Felco or ARS can easily be taken apart and sharpened. Clean cuts, only possible using sharp tools, allow the plant to heal and reduce insect and disease infestation. For pruning techniques, the American Horticultural Society book on pruning and training is an excellent reference.
3) Deadhead plants.
One of the benefits of native plant gardens is their ability to reseed and naturalize over time. Leaving flower parts in place over the winter allows the seed of many species to spread and provides a critical food source for birds, wildlife, and insects over the winter. Removing those spent flower parts in the spring can help clean up the garden and maintain its aesthetic appeal. However, this is optional. We’ve had a number of clients over the years who choose to leave the dead flowerheads and old plant parts as part of the natural cycle. They eventually disappear, but many people prefer a neater garden to start the year. Your choice.
4) To mulch or not to mulch, that is the question.
Standard landscaping practices normally include adding mulch to gardens a few times a year. Is that really necessary with native plants? Good question. In fairly young gardens (say less than 5 years old), we’ll add a mulch in the spring to help with building a healthy soil. But we won’t use a high lignin mulch like bark dust or chips. Those are effective in reducing weed growth, but there is some controversy about their effect on nitrogen cycling in soils. Some studies suggest that the use of high-lignin mulch reduces nitrogen availability in the first few inches of soil (where most of the feeder roots are located), and some studies report that those impacts are dependent on soil type. One recent study found that use of chips in a garden resulted in reduced plant growth and vigor, but was inconclusive on the mechanism that reduced growth rates.
When we do mulch, we commonly use juniper duff — the debris that builds up under juniper trees. That material has the aesthetic components of mulch (dark color, even texture), but includes bacterial communities and fungal hyphae, among other things, that support native plants and help build an ecologically functional soil. As a native plant garden ages, the debris that drops from the plants (for example, all the dead leaves and twigs under a sagebrush) builds up and provides an environment similar to juniper duff where bacteria, beneficial fungi, and everything else becomes functional. After that develops, there’s no need to bring in supplemental mulch as long as you leave at least a small layer of that material (see part 1 above).
The idea is to create a garden that largely takes care of itself. The cycling of nutrients through maintaining a layer of organic matter in the garden is a big part of that.
There are a few standard things that always happen in the spring, regardless of the type of garden you have. These include things like checking the irrigation system and making repairs as necessary, clearing paths and walkways, or checking for safety issues in patios and decks. All sorts of spring chores. Getting your native plant landscape or garden going in the spring is one of our favorite early season activities. It’s not difficult, but it is highly rewarding.
So enjoy the spring (when it finally arrives) and happy gardening!
