Fertilize fast or fertilize slow? The pros and cons | The Compleat Home Gardener

Published 2:00 pm Thursday, June 18, 2026

The third week of June is a good time to fertilize your hanging baskets and container gardens as they put on rapid growth with the warmer night temperatures.

Using a water soluble fertilizer such as Miracle Grow or Peter’s means the product is mixed with water and is absorbed quickly by the plants. The disadvantage is the risk of fertilizer burn if the plant takes in the nutrients too quickly or you make up too strong of a fertilizing brew.

Liquid plant foods that come from an organic source such as fish fertilizers or algae are less likely to burn but will not have the uniform supply of nutrients and micronutrients that some plants need.

Slow release plant foods such as Osmocote that contain all nutrients and micronutrients needed are the easiest to use as you only need to feed the plant once and the little pellets release nutrients all summer every time you water. The disadvantage is the price and that the fertilizer release is dependent on the soil being warm and moist. In Western Washington this means it could be mid-June before the slow release pellets begin to feed the plants.

Mixing a granular fertilizer into the soil is another way to feed hungry plants this summer and the best advice when using purchased plant food is to read and follow the label directions.

Q. My tomato plants have some leaves that have turned purple in color. Yes, not yellow or brown or green but purple. Is this okay and should I pull them off? N.G., Bonney Lake

A. Purple leaves on tomatoes are a sign your nights got too cold. This most likely happened last month but tomatoes hate cold nights under 45 degrees so turn purple in distress. Snip them off if you want to improve the appearance of the plant but warmer nights are here and your tomato plants will recover.

Q. I planted peas earlier in the spring around the first of April. I planted an entire row of seeds. Only a few have sprouted and look really healthy, but what caused the other seeds to not even sprout? Did I plant too early? J. Email

A. Peas and Sweet Peas love to be planted when the weather is cool, so you did plant at the correct time. Most likely the pea seeds became the dinner of either an underground attack by voles or mice or an overhead attack by crows.

I would dig into the soil to see if you can find any seeds that look rotted from heavy, wet soil but because some of your seeds did sprout and look great, I suspect your soil is fine, but you were just robbed.

Are there any crows in your neighborhood? These smart birds have figured out if they see humans working the soil they will most likely find seeds to dig up as soon as you leave the area. They may even be reading the seek packs to see what you are planting.

Tip: To protect pea seeds from theft first pre sprout the seeds by wrapping them in a damp dish cloth. This will discourage the voles who prefer hard seeds over emerging seedlings.

To keep the crows from feasting, cover the newly planted row with netting or screening well secured with bricks or stones until the seedlings emerge. Don’t forget to protect new seedlings from slugs as well. One rainy night can entice a herd of slugs to devour new growth of dahlias, lettuce, annual flowers and peas.

Q. When is the best time to prune rhododendrons? I have a plant that is so tall it is blocking my living room window. It was supposed to be a dwarf variety but is now over four feet high. W., Email

A. Pruning after blooming is the general rule of green thumb and so June is a good time to shorten the branches of lanky rhododendrons by at least one third keeping in mind that where you make the cut is where the new growth will sprout.

Some varieties can even be cut back to mere stumps and in a few years, they will regenerate into bushy shrubs. A better solution may be to transplant that enthusiastic rhododendron to a spot where it can grow as large as it desires. This will eliminate the task of constant pruning to keep your windows clear, and you can instead grow an evergreen azalea that is much more likely to stay under four feet tall.

Tip: In Western Washington our mild climate means that plant labels seriously underestimate the mature size of a shrub. Plan for more height.

Marianne Binetti has a degree in horticulture from Washington State University and is the author of “Easy Answers for Great Gardens” and several other books. For answers to gardening questions, visit plantersplace.com and click “As The Expert”. Copyright for this column owned by Marianne Binetti. For more gardening information, she can be reached at her website, www.binettigarden.com.