What follows bulbs

Jim McKenney jimmckenney@starpower.net
Sun, 15 Aug 2004 12:20:54 PDT
At 03:33 PM 8/14/2004 -0700, Jane McGary wrote:

>What plants -- ornamental or edible -- do others sow over their bulb beds?

Before answering this question, let me make and emphasize a distinction
which is very important in our climate. Bulbs here fall naturally into two
groups: 1) those which survive and increase when left in the ground all
year ("garden bulbs" in my view) and 2) all the others, hardy or tender.
Sadly, the second group is the larger and includes many of the most
interesting bulbs. 

And another basic point: we all vary with respect to the degree of trouble
to which we are willing to go. I took Jane's question to include an element
of labor saving (but maybe that's not what she meant). Furthermore, I want
a "natural" effect - maybe a ridiculous thing for a gardener to say, if
only because gardeners are one of Nature's implacable enemies. What I mean
by "natural effect" is a cycle of growth which imitates in some ways that
of the natural world. Not for me those arrangements where the boy appears
weekly to rip out the pansies - so "last week" -  and replace them with
stocks - and so on all summer. Those who can afford that sort of thing
should just cut to the quick and buy dozens of name-card holders and put
those in their flower beds holding up the ultimate green manure of our
culture, those pictures of dead presidents. Andrew Jackson's aquiline stare
might even scare away some garden pests. 

For the second group, whose most important member is the tulip, sowing or
planting over the bulbs is not likely to produce good results unless you go
to considerable expense or trouble. The bulbs have to be dug, and any
companion plants are likely to suffer from the disturbance. 

Tulips left in the ground start to rot in early June, so there is not much
of a window for companion plants. Many of the plants traditionally
recommended for this use are, in our climate, burn-out annuals, i.e. plants
which are adapted to start under cold/cool conditions and which close up
shop as soon as the hot, humid weather arrives. Typical examples are
pansies, forget-me-nots, poppies in general, stocks, night-scented-stocks,
Calendula, Nigella, larkspurs and so on. If you grow these over your bulbs,
you will probably have to postpone digging the bulbs long enough to
endanger the bulbs. These annuals do provide a secondary wave of color, and
many gardeners do overplant with them. But to do so is to endanger the
tulips - or to present yourself with the hard decision of choosing between
the by then sere and perhaps dimly remembered tulips and a bed of six foot
larkspurs in their full glory. In any case, by July you will be wishing you
had planted something else - or at any rate looking for something to fill
the gaps as the burn-out annuals slump. For those of you who don't mind, go
for it!

The sort of strict management which allows continuous color requires in our
climate a sort of military rotation of the troops: as soon as each bit of
color fades, new fresh troops are brought in to fight the battle. That
means either that there are reserve beds whose developing plants serve to
replenish the main display bed, or there are periodic and expensive trips
to the local garden center. We all have to decide for ourselves whether the
expense is worth the result. 

Jane's question concerned plants suitable for growing over bulb beds - and
I take that to mean beds where the dormant bulbs are still in residence.
I've toyed with this question for years. It's a natural one for the bulbist
because so many bulbs are summer dormant. In this garden, long experience
has led me to certain practices which make sense and, although they involve
compromises, give satisfying results. Initially, it seemed to make sense to
try to combine vernal bulbs with late blooming perennials. Some such
combinations do work, but a surprisingly large percentage of late blooming
perennials make their presence known in the garden very early in the year.
In other words, they are competing with the bulbs for space and light.
Autumn anemones are a good example. If you do mix bulbs with non-bulbous
perennials, group the bulbs; and group them in masses large enough that
when they are dormant, you are left with a broad area for filling in with
some bedding plant. This avoids the spotty look you'll get if the bulbs are
scattered among other perennials. Many plants used as annuals always look
like annuals no matter how you handle them. On the other hand, many will
harmonize with perennials well if given room and if planted in sizable
masses. Incidentally, the harmony I'm alluding to here is not color
harmony, but rather harmony of growth form. The main problems with grouping
annuals (or plants used as annuals)  and perennials seem to arise from
their typically different growth cycles and rates. You'll soon learn that
the shape of a burgeoning annual is protean.  

So what's left if you want to overplant bulbs which are left in the ground?
For that use, there is one plant which in my experience is superlative:
Begonia grandis (B. evansiana). Why is this plant so much better than the
many other plants which seem to fit the bill? The main advantage presented
by the Begonia is that it is very late to start into growth. The bulbs -
assuming they are vernal bulbs - grow and die down without a bit of
competition from this plant. The Begonia starts to push up at about the
time the bulb foliage is collapsing.  They are an ideal compliment. 

The Begonia grows best in very bright light or partial sun; it's definitely
less good in deep shade (although it is one of those plants generally
cursed with the description "shade-tolerant"). In full sun, the Begonia
foliage can burn a bit, but if anything such plants grow more vigorously.
It has what it takes to take over chosen real estate: it's not weedy here,
but it does stake out a claim and hold on to it. 

The Begonia will be a presence in the garden until heavy frost or even
after - the drying stems with their dangling seed capsules are not
unattractive. Because of this prolonged season, it's not a good choice for
use over autumnal Sternbergia, Colchicum, Crocus, Cyclamen or other low
growing plants. It is ideal with daffodils, squills, hyacinths,
ornithogalums and anything else which is up early and gets its business
over with by late May or early June.

Some of the Lycoris squamigera in the garden grow with the Begonia over
them: it's a good combination, especially in those years when the first
Begonia flowers are open with the Lycoris.

That's my best candidate. 

And I'm experimenting with others: for instance, there are bulb beds here
which are covered with glass during the summer. Rather than look at bare
dirt, I'm experimenting with hardy succulents. Presumably they need some
moisture, but otherwise the dry, brightly lit conditions should suit them.
Also, I have my eye on those purportedly hardy South African
mesembryanthemaceous plants such as Delospermum. In my experience, these
have not been reliable in the open garden. But maybe with the glass over
them they will find conditions more to their liking. 

What are others doing? 

Jim McKenney
Montgomery County, Maryland, USA, USDA zone 7, where much of the garden is
planted "old-world-cemetery" style, i.e. with the newcomers put in over the

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