March garden checklist

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Mystery of the month

Why are these tomato seedlings bent sideways?

What should you do if you started seeds and the seedlings have grown poorly?

The solution is at the bottom of this article.

Pests and diseases

Avoid oak wilt issues by having oaks pruned by the end of the month.

One way oak wilt is spread is by sap beetles that are attracted to fresh wounds, particularly from April to June. Oak wilt can kill some red oaks in just a few weeks, so it is important to avoid pruning during the growing season.

Trees and shrubs

Gently remove heavy March snow loads from bending branches on evergreens and other trees with horizontal branches. Start at the bottom and work your way up the plant. You may have to go back to the lower limbs, as snow from the upper limbs falls onto them as you brush it off.

lowers and other garden plants

Bring overwintered geraniums and other dormant flowering plants out from their dark, cool storage areas.

By the end of the month, pot up any plants that need a refresh, water them well, and place them under grow lights.

Houseplants

Clean the leaves on your houseplants with a soft, damp cloth. Dust blowing around from forced air can settle on leaves and block the amount of light the plants receive. Make sure you wipe the top and bottom of the leaves.

It is also important not to spread any insects or diseases from one plant to the next as you clean the leaves. If one of your plants has an insect issue, like scale, make sure you use a new, clean cloth on other plants.

Lawn

As snow melts, some tunnels created by voles can kill grass, delay spring greenup, and create spaces for weeds.

If and when our lawns begin to wake up, you might notice some damage from voles burrowing throughout the turf canopy over winter. You can lightly rake up this debris, but try to wait until the lawn begins to grow.

Even though most of the snow and ice have melted, we may get more wintry conditions. The lawn can be stressed further if aggressive raking occurs before it has the conditions to recover.

Your lawn will begin to grow when soil temperatures reach the mid 40’s. If there is no vole damage, do not rake your lawn; allow it to gradually wake up as air and soil temperatures rise. 

Other tasks

Watch for early spring bulbs that may be emerging from the soil this month.

You may need to gently pull leaves and other mulch away from the plants, as shown in this Hort Short video about pulling mulch away from perennials.

Solution to the mystery of the month

Bending toward a light source is a great indicator that the plants were not getting enough light to grow well.

Most grow lights should be kept 2-4 inches above the tops of the plants, particularly for seedlings. Grow lights should be on for 12-16 hours for most seedlings. Adjust your lights to be closer to the plants by either lowering them or propping the plants up.

• If this happens to tomato or basil seedlings, you can plant them deeper in the soil in May to get shorter, stronger plants.
• If this happens to pepper or eggplant seedlings, do not bury the plants deeply—they do not transplant well when buried deeply.

Read more about starting seeds indoors to grow healthy plants for your garden.