Zone 5, 6 is better, according to the UConn plant database. I've heard it's invasive in some areas, may want to check it out first.

Here is a link that might be useful: link

Hardy enough to be listed as an invasive species by various local organizations, including the New England Exotic Pest Data Base and the Invasive Plant Atlas of the Northeast.

Do not plant common Scotch or English broom, Cytisus scoparius. If you must grow broom (and I am a broom lover myself) seek out one of the sterile hybrid cultivars, like 'Warminster', 'Zeelandia', 'Hollandia', etc.

I ordered Cytisus scoparius 'Moonlight' from Lazy S'S Nursery this year. They have several cultivars listed...(nice plants & service too). I grew this cultivar for several years in previous garden and never any seedlings. Very nice for cutting, too. josh

Here is a link that might be useful: Lazy S'S Nursery

Josh, unfortunately 'Moonlight' self seeds as freely as unnamed forms of C. scoparius. A drive along the freeways here in midspring reveals a host of these plants proliferating along the freeway verges............ an attractive but bothersome contrast of the pale yellow 'Moonlight' against the brighter yellow species. The seeds are indeed extremely viable and the plant just as prone to invasiveness as the straight species.

I really like Warminster broom but feel it is barely hardy here in zone 6a...in other words there is some winter dieback that I have to prune out. But I do enjoy it in the spring with it's sweetpea like flowers and scent.

Patty

Gardengal48, Thanks so much for the caution re C. Moonlight. I grew it in a container in my GA garden for several years but probably gathered all flowering stems for arrangements, thus no seeding. It's too hot here for enjoying garden much in summer plus I like my flowers close up...lol I promise to do the same with my new plant.

I always watch for your posts...thamks for taking time to add your always helpful and knowledgable comments. josh

I have a Moonlight and have never seen a single seedling anywhere. It's not a plant that readily reseeds around here. I have never seen it ever, in the wild. Even the bright gold common broom is fairly rare in this area.

I just have to add my "two cents"...I have several different brooms including the Moonlight and I've happily potted several seedlings that seem to have grown from a spreading root. For me, they aren't invasive at all.

i don't know about z.4. i would suggest calling some of your reputable nurseries up there and asking them.ask millikens in concord or uncanoonic mountain nursery in goffstown. they will steer you right. you should also be able to get zone hardiness for millions of plants by googling them, if you don't have any catalogues or reference books.

Regarding invasive species...it is helpful to know how the plant "invades". For example, some people don't realize that the many of the most invasive species will actually be very well-behaved in one's garden..not spreading by runners or suckering and such...but have berries that birds eat and take into the woods. Or they have seeds that are mowed down and pulled in one's garden but spread to outlaying wooded areas, meadows and marshes where they grow and crowd out native species.

In the case of scotch broom, the seed pods are waterproof and long-lasting. They are spread by birds and animals. The plant then invades grasslands but does not do well in woodlands.

While a noxious pest in parts of the west and the west coast, Scotch Broom has not been found to be invasive in New England. It was evaluated by the Massachusetts Invasive Plants Advisory Group in 2005 and it did not meet criteria to be named even likely or potentially invasive. It is simply not hardy enough in this area, nor is there enough of a suitable habitat for broom to go crazy here in the Northeast. In addition, the Warminster Broom, is considered to be an especially non-invasive cultivar.

Patty

There seems to be some differing opinions. The Nature Conservancy lists Cytisus scoparius as an alien invasive in California, Delaware, Georgia, Massachusettes, North and South Carolina, New York, Oregon, Tennessee, Virginia and Washington. It has naturalized in areas of Martha's Vineyard. And it is listed as an invasive species by the Invasive Plant Atlas of New England. Obviously, it is hardy enough to proliferate to the extent it would be considered suspect by these agencies.

Here is a link that might be useful: IPANE

Less4 -
I don't know if you are still interested in your original question, but it won't be hardy here. (I live just north of Concord, NH.) For a while several years ago, one type of cytisus was sold around here ~ 3-4 feet tall with maroon and yellow flowers (sorry but I don't know the variety by now.) I saw it planted in a bunch of places and put a plant in my own garden not knowing that it might be invasive, and it returned after winter in not one of the places I saw it planted over two or three years. So, you can be pretty sure that it isn't hardy around here.

I planted 3 2 gallon bushes of cytissus moonlight in September of 06. As of today, April 07, the twigs look brown, and there appears to be no green stems at all. This winter in Pgh was strange, with a record 3 day low of -5 F. Any information would be greatly appreciated. I also planted last year a southern magnolia (Browns bracken beauty??) All the leaves are brown and are falling off. Are these plants dead??

I've never heard of broom plant, but I just bought a Moonlight broom and I can't wait to plant it and see what it looks like as it grows. I have a different view of "invasive" plants. Like weeds, they are super hardy. Unless, they choke out other plants, like kudzu, I don't mind their free spreading habits. The fence on my back property right now is in bloom with the "invasive" yellow honeysuckle and I love it. It smells wonderful, looks very pretty as well. I also have a row of burning bushes along my driveway and they are beautiful, especially in the fall. I've not seen them spread at all, but if they did resow themselves, I'd replant them along other borders of my property. I love the large wild pink roses that grow along fencer ows and bloom freely in the spring. How are they any different than the knockout roses everyone wants to buy. Is it wrong for them to replant themselves instead of having to fuss over having a rosebush that is full of mildew and bugs or have to pay a premium price to own one? They are a superior type of rose in my view and give freely of their beauty. Many trees and plants resow themselves and that is how they survive. What's wrong with that?