Four or five tall Manitoba maples line the south fence of my property but on the neighbour’s side. We had them thinned this year but the plants (typical shade plants – hostas, ferns, astilbe etc) are small and straggly.
1) Do the maples deplete the soil’s water and or nutrients?
2) if yes, and I feed/water religiously, will my plants thrive or will the Manitoba maples just get healthier. Sigh.
If a good feeding is a good idea do you know a type of compost and a site for calculating amounts.
Thank you for contacting the Toronto Master Gardeners.
The deep shade under a Manitoba maple is the most challenging garden spot, not just because of the shade but because the maple will consume all the moisture and nutrients, and the roots will take up most of the soil space.
Adding a layer of top soil and sheep manure is an important first step in ‘feeding the soil’ in that area; if the soil is well-nourished, and watered plants will grow well. Using compost and/or an organic mulch between the plants would be recommended; compost will add nutrients to the soil; mulch helps to retain moisture in the soil as well as improving the fertility of the soil. A mulch of ground or shredded hardwood, cedar or pine would be attractive. Since the mulch is organic, it will break down over the season and will need to be replenished each year. Compost should be added both in the spring and fall around the plants.
Have you considered planting spring bulbs in that area? Bulbs, such as Galanthus (snowdrops) or Scilla siberica (squill) will bloom before the tree leafs out. They need to be planted in the fall, but provide early spring interest and colour. There are many colourful options. For more information, see here.
You might like to consider various ground covers. Any of the thymes: for example woolly thyme (Thymus pseudolanuginosus) and red thyme (Thymus vulgaris) are good together in partial shade. Deadnettle (Lamium maculatum) and creeping phlox (Phlox subulata) are good blooming groundcovers for shade, bugleweed (Ajuga reptans) provides a dense groundcover and an evergreen option is Japanese spurge (Pachysandra terminalis). If you wanted a fragrant ground cover try Sweet woodruff (Galium odoratum).
You might like to look at some suggestions in our Garden Guide: Perennials for Shade in Dry or Moist Areas