Here’s what a cover crop is and why you should plant one for your garden soon

  • Author: Jeff Lowenfels
    | Alaska gardening
  • Updated: August 23, 2018
  • Published August 23, 2018

Gardeners always have the urge to plant. It is a hard one to satisfy this time of year, as we should be thinking of harvesting and putting things to bed. A big exception is cover crops.

People plant cover crops for two main reasons: to fight weeds by blocking them out and to add nitrogen and biomass to the soil. This time of year we are not so much concerned with blocking out weeds as we are with adding nutrients to the soil for next season. Cover crops are called "green manure," and this is why you might want to plant now in your vegetable gardens. In order to give some benefit, a cover crop needs to be planted so you get at least four weeks of growth before the frost hits.

If you are looking to put nitrogen into your soils, use annual clovers. If you want to add biomass to help break up compacted soil and add all manner of nutrients you can use ryegrass or alfalfa. If you go with the clover for nitrogen, then you should inoculate the seed first with rhizobia, the nitrogen-fixing bacteria you want to grow in nodules that form on legumes. You should be able to find Rhizobia inoculants locally at all nurseries.

Next, it is too early to put spring flowering bulbs into the ground, but heed this: I am just back from a Garden Writers Association conference and the word is there was not the best crop of bulbs this year in Holland. Orders in some categories are not going to get filled. Order now if you do so from Outside. Otherwise, buy when you see them locally for sale. Don't wait.

OK, right now garlic lovers should consider finding a few varieties that you want to grow. Now is not the time to plant, that is next month, but you have to have some on hand in order to plant it, and it will take a couple of weeks. You can pick up some of the bulbs sold by your favorite grocer, but these may have been treated with chemicals to slow sprouting. More important, you can buy those varieties at the store, so why waste precious gardening space growing them? Find some new and different varieties.

Look for bulbs when you visit your favorite nurseries this weekend. This is also an instance where it makes sense to look at selections online. High Mowing Seeds (, Territorial Seed ( and Renee's Garden ( are good places to start looking, as they all have simple explanations of what to look for. Even better, Alaska Cooperative Extension has great information on their site, "Growing Garlic In Alaska."

And, since I mentioned the Extension, here's a heads up to would-be master gardeners. The only master gardeners class in Anchorage (you can drive out the to Valley) until 2020 is filling up. Register right now at 907-745-3639. Why, oh why did our government move this group away from here?

Back outdoors, it is as good a time as any to divide rhubarb. You can either dig up the whole plant and then split it up or simply dig into the middle of the plant, splitting it and digging out half. Add soil back to the hole and plant the new half where you want it.

You can also divide iris clumps. It is best to dig these up and divide by hand into size portions you desire.

And, of course, you should be harvesting those veggies and enjoying a few cut flower bouquets, too. Hopefully, you are the kind of gardener who understands that just looking at what you grow isn't really gardening. That is landscaping.

Finally, now is also a good time to repot houseplants, our neglected friends. The reason is you can do it outside. Get the best potting soil you can: full of organic matter, composted, and with good drainage. The advice to add something to the bottom of the pot, over the holes, to help with drainage is wrong so ignore it. Don't tamp down the soil. It will settle around roots during the first watering. Give your plants plenty of room since I know you have a set of winter lights for your houseplants to grow under so they will need it.

Jeff's Alaska garden calendar

Anchorage Master Gardener Classes in Anchorage: This is the last one in Anchorage until 2020. Starts Sept. 11. You'll need to register by Sept. 5. The cost is $300, and it's worth it. Call Steve Brown at 907-745-3639. Swamp them. We need a full-time office.

Mushroom walk: Sept. 6 at Alaska Botanical Garden 6-7:30 p.m. Tickets are $20-25. See for details.

Plant a row for the hungry: Do not let things go to waste. There is someone who wants your excess, be it Bean's, one of the many state food banks, houses of worship or even a deserving friend. Gardeners, especially Alaskan ones, share.

Local food leader training: For anyone interested in helping with and developing our community food system, see for more info.