Bulbs for Under Trees

>> Sunday, November 16, 2008

One of the many projects on my growing ‘to do’ list is to remove the grass that is growing right up to the trunks of my trees. The trees are all mature so the grass itself does not create any problems for the trees, they have all learned to get along well when it comes to getting nutrients and water. So, it is actually just an aesthetic thing for me.

In the backyard, there is a peach tree, a pear tree, a cherry tree, and an apple tree. I also have a plum tree, but it is in a raised bed without any grass around it. However, I also plant vegetables there and am using that same bed as a nursery of sorts for a couple of Lilac bushes that will be transplanted in the near future.

In the front yard, there is a Dogwood tree, variety unknown since it was here when we moved here, and a Catalpa tree.

I am fortunate in that none of these trees have surface roots. You know, the ones you trip over whenever walking near them? Even with these underground roots, planting anything else near them will compete for water and food so I have decided to place some bulbs around them. A word of caution, bulbs will not do well under pines or evergreens, because bulbs just like other plants need sunlight. Another consideration is the higher up the limbs are on the tree trunk, the more light your bulbs will get.

I have discovered some spring-flowering bulbs, particularly those from woodland habitats, that thrive under mature trees. These types of bulbs differ from other more commonly known spring bulbs, such as Daffodil and Tulip, in that they are shorter and flower and set seed quickly at the first signs of spring, before the tree canopy robs them of light and water. Then they die back and sleep until the next year just as you expect a well-behaved bulb to do.

Spring-flowering bulbs to plant under trees include English bluebell (Hyacinthoides non-scripta), Camas lily (Camassia leichtlinii), winter aconite (Eranthis hyemalis) and snowdrops (Galanthus nivalis).

English bluebell, aka blue squill, grows in zones 4-9, member of the lily family (Liliaceae). It flowers from May to June and seeds ripen from July to August.

Camas lily grows in zones 5-9, late spring/early summer. The bulbs were collected for food by Native Americans. Best placed in areas where they can naturalize and won't be disturbed. They take well to summer dryness as they go dormant by early summer. This plant grows 3-4 feet tall and 2-3 feet wide, so I’m a little concerned about putting it under a tree.

Winter aconite grows in zones 3-7, blooms March to April, member of the Ranunculus family. Late winter bloomer, before crocus, they often send their shoots up through snow.

Snowdrops grows in zones 3-7, blooms in February, member of the Amaryllis family. Also pokes its head up through snow. Easily naturalizes in woodland areas or in lawns under large deciduous trees.

I already have some winter aconite and snowdrops scattered throughout a couple of beds, nowhere near any trees. Now that I have learned that these can go under the trees they will be moved next fall. It will be time for them to be dug up and divided anyway so that will be a perfect time to move them.

Bulbs that flower in fall can also do well under trees. They flower then produce leaves. By the time their foliage appears, the tree canopy has thinned, allowing light to hit the bulbs’ leaves, allowing the bulbs to rebuild their energy stores.

Fall-flowering bulbs to plant under trees include Cyclamen hederifolium and autumn crocus (Colchicum autumnale).

Cyclamen can grow in zones 5/6 as long as a few rules are observed. Hederifolium puts out roots from the top and sides of the tuber, unlike Cyclamen coum and the like which have roots on the bottom surface only, so they need to be planted with the tops of the tubers a couple inches deep (place soil up to the top and then cover the top with a couple inches of coarse grit rather than garden soil). The best locations are on a north facing slope under a tree, or on the north side of the house that doesn’t get any direct sun in the winter. Sunlight makes the normal freeze/thaw cycles even worse. Note: if you see ants on these plants don’t worry, this is a good thing because they disperse the seed.

An interesting fact that I just learned is that the Cyclamen is a member of the Primrose family.

Cyclamen mirabile is a very cold-hardy species. Mature leaves will go limp after a frost but soon recover. Some forms have a reddish cast over the silver of the variably marbled, but always attractive, leaves.

Cyclamen graecum is one of several species that will pull themselves into the soil with contractile roots, thus setting their own planting depth. The leaf marbling is extremely variable. This species may prefer a more open site with good sun exposure in summer as long as the persistent roots can be in slightly moist soil.

Autumn Crocus (Colchicum autumnale) – aka ‘meadow saffron’ or ‘naked lady’, grows in zones 4-8 (easily survives winter temperatures a little below 0ºF, -17ºC) and resembles true crocuses, but actually flowers in autumn. But, so do many other crocuses.

It is a member of the Iris family (iridaceae), grow from corms, are mainly hardy perennials, and are found in a wide range of habitats.

It should be noted that it's not a crocus, and it's not saffron, and should definitely not be used in place of saffron in cooking because eating any part of this plant can kill you. The spice saffron is collected from the stigmas of Crocus sativus not Colchicum autumnale.

Plant them in late summer or early fall. Position the tip of the corm 2-4” below the soil level. To protect flowers from soil that can be splashed up when it rains, plant corms under low-growing carpeting plants or in grass.

It is getting a bit late in the year to plant spring-flowering bulbs, but now I can amend my ‘to do’ list and finally move ‘clear grass from around tree trunks and plant something’ up the list for next year.

Further reading:
Cyclamen Society
Autumn crocus


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